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K3 Manual change suggestion

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Ken Widelitz

K3 Manual change suggestion

I've been studying the Main/Sub RX Antenna Routing section with an eye
towards how the RX ANT OUT is used. Unless I'm missing something, it isn't
clear in the manual. The answer, YOU NEED TO TURN ON THE RX ANT, is
contained, in a different context, in the following reflector post from
Wayne, which should be integrated into the manual.

73, Ken, K6LA / VY2TT

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wayne burdick

Re: K3 Manual change suggestion

Administrator

I'll certainly try to improve the manual in this regard, Ken. Thanks
for the suggestion.

73,
Wayne

On Mar 14, 2009, at 2:53 PM, Ken Widelitz wrote:

> I've been studying the Main/Sub RX Antenna Routing section with an eye
> towards how the RX ANT OUT is used. Unless I'm missing something, it
> isn't
> clear in the manual. The answer, YOU NEED TO TURN ON THE RX ANT...

> ---

http://www.elecraft.com

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w0mu

Re: K3 Manual change suggestion

In reply to this post by Ken Widelitz

It is also unclear what the real purpose is for the rx ant out. From what I
have been told if I want to share my rx antennas with the two receivers then
I should use a T or splitter and go to each input separately.

I would think that RX Ant Out would allow you to take the RX antenna to
another rig or something.

If I recall correctly was it to be used for some type of flitering?

"A slip of the foot you may soon recover, but a slip of the tongue you may
never get over." Ben Franklin
-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Ken Widelitz
Sent: Saturday, March 14, 2009 3:54 PM
To: [hidden email]
Subject: [Elecraft] K3 Manual change suggestion

I've been studying the Main/Sub RX Antenna Routing section with an eye
towards how the RX ANT OUT is used. Unless I'm missing something, it isn't
clear in the manual. The answer, YOU NEED TO TURN ON THE RX ANT, is
contained, in a different context, in the following reflector post from
Wayne, which should be integrated into the manual.

73, Ken, K6LA / VY2TT

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wayne burdick

Re: K3 Manual change suggestion

Administrator

RX ANT OUT is useful for several things, including patching in
narrowband receiving filters, preamps, etc. A longer description can be
found on page 39 of the most recent owner's manual (rev D).

73,
Wayne
N6KR

On Mar 14, 2009, at 3:18 PM, W0MU Mike Fatchett wrote:

> It is also unclear what the real purpose is for the rx ant out.

---

http://www.elecraft.com

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n6wg

Re: K3 Manual change suggestion

In reply to this post by w0mu

The RX OUT/RX IN ports allow you to insert
whatever you want in the receive path for the
main rcvr.
It could be a filter, a preamp, an attenuator or
whatever.
73, Bob N6WG

----- Original Message -----
From: "W0MU Mike Fatchett" <[hidden email]>
To: "'Ken Widelitz'" <[hidden email]>; <[hidden email]>
Sent: Saturday, March 14, 2009 3:18 PM
Subject: Re: [Elecraft] K3 Manual change suggestion

> It is also unclear what the real purpose is for the rx ant out. From what
> I
> have been told if I want to share my rx antennas with the two receivers
> then
> I should use a T or splitter and go to each input separately.
>
> I would think that RX Ant Out would allow you to take the RX antenna to
> another rig or something.
>
> If I recall correctly was it to be used for some type of flitering?
>
>
> "A slip of the foot you may soon recover, but a slip of the tongue you may
> never get over." Ben Franklin
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Ken Widelitz
> Sent: Saturday, March 14, 2009 3:54 PM
> To: [hidden email]
> Subject: [Elecraft] K3 Manual change suggestion
>
> I've been studying the Main/Sub RX Antenna Routing section with an eye
> towards how the RX ANT OUT is used. Unless I'm missing something, it isn't
> clear in the manual. The answer, YOU NEED TO TURN ON THE RX ANT, is
> contained, in a different context, in the following reflector post from
> Wayne, which should be integrated into the manual.
>
>
>
>
>
>
>
> 73, Ken, K6LA / VY2TT
>
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

Dave, G4AON

Re: K3 Manual change suggestion

In reply to this post by Ken Widelitz

Mike the RX ant out is the same as those RF in/out phono sockets found
years ago on radios like the Icom IC720A. I use mine to feed a second
receiver (Microtelecom Perseus), if you want to feed a second receiver
you will need a ferrite splitter which is easy to make, there are three
ports, one from the RF out, one back to the K3 and the other to the
second receiver. Details halfway down my K3 page at:

http://www.astromag.co.uk/k3/

73 Dave, G4AON
================
It is also unclear what the real purpose is for the rx ant out. From what I
have been told if I want to share my rx antennas with the two receivers then
I should use a T or splitter and go to each input separately.

I would think that RX Ant Out would allow you to take the RX antenna to
another rig or something.

If I recall correctly was it to be used for some type of flitering?
______________________________________________________________
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Stephen W. Kercel

Tuning Pulser with K2

In reply to this post by n6wg

Elecrafters:

I built a tuning pulser to use with my K2/100 to tune an external linear
amplifier. The pulser is the AG6K design. The pulse is 12 ms on and 24
ms off, and repeats about 28 times per second. This is (by design) much
faster than the normal 25 wpm or so keying out of the keyer.

The interface between the pulser and the K2 is a 2N2222 NPN transistor
used as a switch. The key line to the K2 is connected to the collector
of the transistor (nothing else is connected to the collector), the
switching data comes in through the base, and the emitter is grounded
both to the ground side of the pulser circuit and the ground side of the
keying line back to the K2.

I notice what seems to me to be an odd phenomenon when I key the K2 with
the pulser. When I first switch on the pulser, the power level in the
little LED power meter on the K2 shows the same power level as I get in
normal keying. However, after the first instant, the power level
indication drops one bar lower (and then stays there as long as the
pulser is on) than the power level indication under normal keying. This
effect occurs independent of the power level that I set. It happens with
the K2's 100 Watt amplifier both in and out.

Is this simply an artifact of the metering circuit caused by the
peculiar duty cycle of the pulser?

Most critically, will it harm the K2?

Should I do as one alternative keying scheme shows, and use the
transistor to key a reed relay and use the reed relay (which would
simply hard short the K2 keying line on key down) to key the K2?

TNX & 73,

Steve Kercel
AA4AK

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Don Wilhelm-4

Re: Tuning Pulser with K2

Steve,

I have not yet seen an answer on the reflector, so I will offer some
comments.
First, I do not think your pulser will hurt the K2 in any way.
Secondly, I am at a loss to know why you do not see as many bars in the
K2 LED display as you do in TUNE. The bargraph is relatively fast
responding and should indicate the power level being transmitted. It
may be that your pulser ON duration is too short and it causes a
'flicker' in the display that is not seen by the eye.
It would be interesting to see what an oscilloscope connected across the
K2 output would reveal (the oscilloscope display would react in even
less time than the bargraph).

So, bottom line, you may be seeing a natural result of the pulser ON
time rather than an actual fault of the K2. Is there an easy way to
double the ON time for your pulser? I find it hard to believe that 24
ms of ON time would cause any problems for your amplifier - it certainly
would not pose any problems for the K2.

73,
Don W3FPR

Stephen W. Kercel wrote:

> Elecrafters:
>
> I built a tuning pulser to use with my K2/100 to tune an external linear
> amplifier. The pulser is the AG6K design. The pulse is 12 ms on and 24
> ms off, and repeats about 28 times per second. This is (by design) much
> faster than the normal 25 wpm or so keying out of the keyer.
>
> The interface between the pulser and the K2 is a 2N2222 NPN transistor
> used as a switch. The key line to the K2 is connected to the collector
> of the transistor (nothing else is connected to the collector), the
> switching data comes in through the base, and the emitter is grounded
> both to the ground side of the pulser circuit and the ground side of the
> keying line back to the K2.
>
> I notice what seems to me to be an odd phenomenon when I key the K2 with
> the pulser. When I first switch on the pulser, the power level in the
> little LED power meter on the K2 shows the same power level as I get in
> normal keying. However, after the first instant, the power level
> indication drops one bar lower (and then stays there as long as the
> pulser is on) than the power level indication under normal keying. This
> effect occurs independent of the power level that I set. It happens with
> the K2's 100 Watt amplifier both in and out.
>
> Is this simply an artifact of the metering circuit caused by the
> peculiar duty cycle of the pulser?
>
> Most critically, will it harm the K2?
>
> Should I do as one alternative keying scheme shows, and use the
> transistor to key a reed relay and use the reed relay (which would
> simply hard short the K2 keying line on key down) to key the K2?
>
> TNX & 73,
>
> Steve Kercel
> AA4AK
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.0.237 / Virus Database: 270.11.13/2001 - Release Date: 03/14/09 06:54:00
>
>

Stephen W. Kercel

Re: Tuning Pulser with K2

Don:

I'm glad to hear from you on this. I talked to Scott at Elecraft earlier
in the day, and he said that he had never heard of anyone using a tuning
pulser with a K2, but that if anyone would understand the possible
quirks it would be you.

In addition to the "one bar less than normal keying," I have discovered
another quirk. If I change bands, and then try to run the pulser, the
transmitter does not key. I hear the side tone, but the K2 power meter
shows no bars. Also, the peak reading Watt meter in series with my dummy
load shows no RF output. I can remedy the problem by reverting to the
regular keyer and tweaking the power level between QRP and QRO levels.
Somehow this seems to reset something in the rig. Once it transmits at
regular keying speeds, if I subsequently go to the tuning pulser, then
the K2 will transmit the pulses.

I have not yet looked at the RF output on a scope. What I have noticed
is that once the transmitter does turn on, the peak reading Watt meter
in series with the dummy load gives me about the same peak reading both
for the pulser and normal keying.

These various quirks do suggest to me that the the 12 ms "on" interval
is too short for the K2 to respond properly. Thus, your suggestion of
doubling the "on" interval sounds like a good possibility for
sidestepping these quirky behaviors. Both the "on" and "off" durations
are determined by a 0.1 uF capacitor in the timing circuit of the
pulser. If I change the capacitor to 0.18 uF (values of 0.2 uF seem hard
co come by), it would change the "on" interval to 22 ms and preserve the
33% duty cycle.

Unfortunately, the local Radio Shack does not carry these values, and
I'll need to order a new capacitor from Mouser. Thus, it will be a few
days before I can give this modification a try.

I'll let you know how it turns out.

BTW, for those who are curious, the Web page describing the pulser is

http://www.somis.org/D-a-09.GIF

The version that I built is the one transistor version.

TXN & 73,

Steve Kercel
AA4AK

Don Wilhelm wrote:

> Steve,
>
> I have not yet seen an answer on the reflector, so I will offer some
> comments. First, I do not think your pulser will hurt the K2 in any way.
> Secondly, I am at a loss to know why you do not see as many bars in
> the K2 LED display as you do in TUNE. The bargraph is relatively fast
> responding and should indicate the power level being transmitted. It
> may be that your pulser ON duration is too short and it causes a
> 'flicker' in the display that is not seen by the eye.
> It would be interesting to see what an oscilloscope connected across
> the K2 output would reveal (the oscilloscope display would react in
> even less time than the bargraph).
>
> So, bottom line, you may be seeing a natural result of the pulser ON
> time rather than an actual fault of the K2. Is there an easy way to
> double the ON time for your pulser? I find it hard to believe that 24
> ms of ON time would cause any problems for your amplifier - it
> certainly would not pose any problems for the K2.
>
> 73,
> Don W3FPR
>
>
> Stephen W. Kercel wrote:
>> Elecrafters:
>>
>> I built a tuning pulser to use with my K2/100 to tune an external
>> linear amplifier. The pulser is the AG6K design. The pulse is 12 ms
>> on and 24 ms off, and repeats about 28 times per second. This is (by
>> design) much faster than the normal 25 wpm or so keying out of the
>> keyer.
>>
>> The interface between the pulser and the K2 is a 2N2222 NPN
>> transistor used as a switch. The key line to the K2 is connected to
>> the collector of the transistor (nothing else is connected to the
>> collector), the switching data comes in through the base, and the
>> emitter is grounded both to the ground side of the pulser circuit and
>> the ground side of the keying line back to the K2.
>>
>> I notice what seems to me to be an odd phenomenon when I key the K2
>> with the pulser. When I first switch on the pulser, the power level
>> in the little LED power meter on the K2 shows the same power level as
>> I get in normal keying. However, after the first instant, the power
>> level indication drops one bar lower (and then stays there as long as
>> the pulser is on) than the power level indication under normal
>> keying. This effect occurs independent of the power level that I set.
>> It happens with the K2's 100 Watt amplifier both in and out.
>>
>> Is this simply an artifact of the metering circuit caused by the
>> peculiar duty cycle of the pulser?
>>
>> Most critically, will it harm the K2?
>>
>> Should I do as one alternative keying scheme shows, and use the
>> transistor to key a reed relay and use the reed relay (which would
>> simply hard short the K2 keying line on key down) to key the K2?
>>
>> TNX & 73,
>>
>> Steve Kercel
>> AA4AK
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> ------------------------------------------------------------------------
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - www.avg.com Version: 8.0.237 / Virus Database:
>> 270.11.13/2001 - Release Date: 03/14/09 06:54:00
>>
>>
>

Don Wilhelm-4

Re: Tuning Pulser with K2

Steve,

If you recall, it takes about 3 dot intervals (at 20 to 25 wpm) for the
K2 to come up to the requested power after a band change, so what you
are seeing is the result of your short pulses with longer intervals in
between. The K2 power controls may not have time to react with the
short pulses.

Out of curiosity, why are you not just sending a string of dots? It
seems the 'pulser' is a device that could be used for those who do not
have keyers.

73,
Don W3FPR

Stephen W. Kercel wrote:

> Don:
>
> I'm glad to hear from you on this. I talked to Scott at Elecraft earlier
> in the day, and he said that he had never heard of anyone using a tuning
> pulser with a K2, but that if anyone would understand the possible
> quirks it would be you.
>
> In addition to the "one bar less than normal keying," I have discovered
> another quirk. If I change bands, and then try to run the pulser, the
> transmitter does not key. I hear the side tone, but the K2 power meter
> shows no bars. Also, the peak reading Watt meter in series with my dummy
> load shows no RF output. I can remedy the problem by reverting to the
> regular keyer and tweaking the power level between QRP and QRO levels.
> Somehow this seems to reset something in the rig. Once it transmits at
> regular keying speeds, if I subsequently go to the tuning pulser, then
> the K2 will transmit the pulses.
>
> I have not yet looked at the RF output on a scope. What I have noticed
> is that once the transmitter does turn on, the peak reading Watt meter
> in series with the dummy load gives me about the same peak reading both
> for the pulser and normal keying.
>
> These various quirks do suggest to me that the the 12 ms "on" interval
> is too short for the K2 to respond properly. Thus, your suggestion of
> doubling the "on" interval sounds like a good possibility for
> sidestepping these quirky behaviors. Both the "on" and "off" durations
> are determined by a 0.1 uF capacitor in the timing circuit of the
> pulser. If I change the capacitor to 0.18 uF (values of 0.2 uF seem hard
> co come by), it would change the "on" interval to 22 ms and preserve the
> 33% duty cycle.
>
> Unfortunately, the local Radio Shack does not carry these values, and
> I'll need to order a new capacitor from Mouser. Thus, it will be a few
> days before I can give this modification a try.
>
> I'll let you know how it turns out.
>
> BTW, for those who are curious, the Web page describing the pulser is
>
> http://www.somis.org/D-a-09.GIF
>
> The version that I built is the one transistor version.
>
> TXN & 73,
>
> Steve Kercel
> AA4AK
>
>
> Don Wilhelm wrote:
>
>> Steve,
>>
>> I have not yet seen an answer on the reflector, so I will offer some
>> comments. First, I do not think your pulser will hurt the K2 in any way.
>> Secondly, I am at a loss to know why you do not see as many bars in
>> the K2 LED display as you do in TUNE. The bargraph is relatively fast
>> responding and should indicate the power level being transmitted. It
>> may be that your pulser ON duration is too short and it causes a
>> 'flicker' in the display that is not seen by the eye.
>> It would be interesting to see what an oscilloscope connected across
>> the K2 output would reveal (the oscilloscope display would react in
>> even less time than the bargraph).
>>
>> So, bottom line, you may be seeing a natural result of the pulser ON
>> time rather than an actual fault of the K2. Is there an easy way to
>> double the ON time for your pulser? I find it hard to believe that 24
>> ms of ON time would cause any problems for your amplifier - it
>> certainly would not pose any problems for the K2.
>>
>> 73,
>> Don W3FPR
>>
>>
>> Stephen W. Kercel wrote:
>>
>>> Elecrafters:
>>>
>>> I built a tuning pulser to use with my K2/100 to tune an external
>>> linear amplifier. The pulser is the AG6K design. The pulse is 12 ms
>>> on and 24 ms off, and repeats about 28 times per second. This is (by
>>> design) much faster than the normal 25 wpm or so keying out of the
>>> keyer.
>>>
>>> The interface between the pulser and the K2 is a 2N2222 NPN
>>> transistor used as a switch. The key line to the K2 is connected to
>>> the collector of the transistor (nothing else is connected to the
>>> collector), the switching data comes in through the base, and the
>>> emitter is grounded both to the ground side of the pulser circuit and
>>> the ground side of the keying line back to the K2.
>>>
>>> I notice what seems to me to be an odd phenomenon when I key the K2
>>> with the pulser. When I first switch on the pulser, the power level
>>> in the little LED power meter on the K2 shows the same power level as
>>> I get in normal keying. However, after the first instant, the power
>>> level indication drops one bar lower (and then stays there as long as
>>> the pulser is on) than the power level indication under normal
>>> keying. This effect occurs independent of the power level that I set.
>>> It happens with the K2's 100 Watt amplifier both in and out.
>>>
>>> Is this simply an artifact of the metering circuit caused by the
>>> peculiar duty cycle of the pulser?
>>>
>>> Most critically, will it harm the K2?
>>>
>>> Should I do as one alternative keying scheme shows, and use the
>>> transistor to key a reed relay and use the reed relay (which would
>>> simply hard short the K2 keying line on key down) to key the K2?
>>>
>>> TNX & 73,
>>>
>>> Steve Kercel
>>> AA4AK
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> ------------------------------------------------------------------------
>>>
>>>
>>> No virus found in this incoming message.
>>> Checked by AVG - www.avg.com Version: 8.0.237 / Virus Database:
>>> 270.11.13/2001 - Release Date: 03/14/09 06:54:00
>>>
>>>
>>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.0.237 / Virus Database: 270.11.15/2004 - Release Date: 03/16/09 07:04:00
>
>

Stephen W. Kercel

Re: Tuning Pulser with K2

Don:

It is a sensible question.

A string of dots sent at nominal weight typically has a duty cycle of
50% off and 50% on. This is the weight to which I keep my keyer
adjusted, and after sending that way for 45 years, I'm used to it.
Typical SSB and CW sent as real characters have a duty cycle closer to
33% on and 67% off. The idea of the tuning pulser is to adjust the
amplifier using a duty cycle similar to what it will encounter in normal
operation.

Now it is true that I could tune the amplifier by temporarily
readjusting the keyer weighting for a 33% duty cycle, ramping up the
speed to about 40 wpm, keying the radio (which requires actually keeping
a hand on the key) and tuning. Then to revert to normal sending, I reset
the keyer to my normal 20-25 wpm, reset the weight to normal weighting,
and then have at it with my newly retuned amplifier. Note however that
I have added about four steps to the tuning and I am in the extremely
awkward position of trying to keep the string of dots going with one
hand on the key and twiddling the knobs on the amplifier with the other.
To make matters worse, I use a WinKey and the N1MM logger; the N1MM
logger preempts the manual controls on the keyer. That means that in
order to reset the weight of the keyer, I need to go to the N1MM's not
especially friendly parameters menu twice, once top set up the pulser
sequence, and then again to restore normal keying.

As you can see, the above is possible in principle, but extremely
awkward in practice.

In contrast, if I connect the keyer and the tuning pulser (which is hard
wired for a 33% duty cycle) to the K2 via a DPDT switch (one pole
selects keyer vs pulser, the other controls the power to the pulser), I
get my tuning pulses with a single flip of the switch. In addition, both
hands are free to twiddle the amplifier, which means I get the tuning
done non-trivially faster. Finally, to get back to normal sending, I
just flip the switch back the other way.

Unlike the Ameritron pulser which costs about $80 and has a lot of
features that are totally unnecessary, this little pulser costs about
$25 for the parts, and a lot less if you have a decently endowed junk
box. This seems a small price to pay to greatly streamline the tuning
process.

73,

Steve
AA4AK

Don Wilhelm wrote:

> Steve,
>
> If you recall, it takes about 3 dot intervals (at 20 to 25 wpm) for
> the K2 to come up to the requested power after a band change, so what
> you are seeing is the result of your short pulses with longer
> intervals in between. The K2 power controls may not have time to
> react with the short pulses.
>
> Out of curiosity, why are you not just sending a string of dots? It
> seems the 'pulser' is a device that could be used for those who do not
> have keyers.
>
> 73,
> Don W3FPR
>
> Stephen W. Kercel wrote:
>> Don:
>>
>> I'm glad to hear from you on this. I talked to Scott at Elecraft
>> earlier in the day, and he said that he had never heard of anyone
>> using a tuning pulser with a K2, but that if anyone would understand
>> the possible quirks it would be you.
>>
>> In addition to the "one bar less than normal keying," I have
>> discovered another quirk. If I change bands, and then try to run the
>> pulser, the transmitter does not key. I hear the side tone, but the
>> K2 power meter shows no bars. Also, the peak reading Watt meter in
>> series with my dummy load shows no RF output. I can remedy the
>> problem by reverting to the regular keyer and tweaking the power
>> level between QRP and QRO levels. Somehow this seems to reset
>> something in the rig. Once it transmits at regular keying speeds, if
>> I subsequently go to the tuning pulser, then the K2 will transmit the
>> pulses.
>>
>> I have not yet looked at the RF output on a scope. What I have
>> noticed is that once the transmitter does turn on, the peak reading
>> Watt meter in series with the dummy load gives me about the same peak
>> reading both for the pulser and normal keying.
>>
>> These various quirks do suggest to me that the the 12 ms "on"
>> interval is too short for the K2 to respond properly. Thus, your
>> suggestion of doubling the "on" interval sounds like a good
>> possibility for sidestepping these quirky behaviors. Both the "on"
>> and "off" durations are determined by a 0.1 uF capacitor in the
>> timing circuit of the pulser. If I change the capacitor to 0.18 uF
>> (values of 0.2 uF seem hard co come by), it would change the "on"
>> interval to 22 ms and preserve the 33% duty cycle.
>>
>> Unfortunately, the local Radio Shack does not carry these values, and
>> I'll need to order a new capacitor from Mouser. Thus, it will be a
>> few days before I can give this modification a try.
>>
>> I'll let you know how it turns out.
>>
>> BTW, for those who are curious, the Web page describing the pulser is
>>
>> http://www.somis.org/D-a-09.GIF
>>
>> The version that I built is the one transistor version.
>> TXN & 73,
>>
>> Steve Kercel
>> AA4AK
>>
>>
>> Don Wilhelm wrote:
>>
>>> Steve,
>>>
>>> I have not yet seen an answer on the reflector, so I will offer some
>>> comments. First, I do not think your pulser will hurt the K2 in any
>>> way.
>>> Secondly, I am at a loss to know why you do not see as many bars in
>>> the K2 LED display as you do in TUNE. The bargraph is relatively
>>> fast responding and should indicate the power level being
>>> transmitted. It may be that your pulser ON duration is too short
>>> and it causes a 'flicker' in the display that is not seen by the eye.
>>> It would be interesting to see what an oscilloscope connected across
>>> the K2 output would reveal (the oscilloscope display would react in
>>> even less time than the bargraph).
>>>
>>> So, bottom line, you may be seeing a natural result of the pulser ON
>>> time rather than an actual fault of the K2. Is there an easy way to
>>> double the ON time for your pulser? I find it hard to believe that
>>> 24 ms of ON time would cause any problems for your amplifier - it
>>> certainly would not pose any problems for the K2.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>>
>>> Stephen W. Kercel wrote:
>>>
>>>> Elecrafters:
>>>>
>>>> I built a tuning pulser to use with my K2/100 to tune an external
>>>> linear amplifier. The pulser is the AG6K design. The pulse is 12 ms
>>>> on and 24 ms off, and repeats about 28 times per second. This is
>>>> (by design) much faster than the normal 25 wpm or so keying out of
>>>> the keyer.
>>>>
>>>> The interface between the pulser and the K2 is a 2N2222 NPN
>>>> transistor used as a switch. The key line to the K2 is connected to
>>>> the collector of the transistor (nothing else is connected to the
>>>> collector), the switching data comes in through the base, and the
>>>> emitter is grounded both to the ground side of the pulser circuit
>>>> and the ground side of the keying line back to the K2.
>>>>
>>>> I notice what seems to me to be an odd phenomenon when I key the K2
>>>> with the pulser. When I first switch on the pulser, the power level
>>>> in the little LED power meter on the K2 shows the same power level
>>>> as I get in normal keying. However, after the first instant, the
>>>> power level indication drops one bar lower (and then stays there as
>>>> long as the pulser is on) than the power level indication under
>>>> normal keying. This effect occurs independent of the power level
>>>> that I set. It happens with the K2's 100 Watt amplifier both in and
>>>> out.
>>>>
>>>> Is this simply an artifact of the metering circuit caused by the
>>>> peculiar duty cycle of the pulser?
>>>>
>>>> Most critically, will it harm the K2?
>>>>
>>>> Should I do as one alternative keying scheme shows, and use the
>>>> transistor to key a reed relay and use the reed relay (which would
>>>> simply hard short the K2 keying line on key down) to key the K2?
>>>>
>>>> TNX & 73,
>>>>
>>>> Steve Kercel
>>>> AA4AK
>>>>
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
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>>>> ------------------------------------------------------------------------
>>>>
>>>>
>>>>
>>>> No virus found in this incoming message.
>>>> Checked by AVG - www.avg.com Version: 8.0.237 / Virus Database:
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>>>>
>>>>
>>
>> ______________________________________________________________
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>>
>

rfenabled

Re: Tuning Pulser with K2

Sure glad I don't own an old amp that needs tuning...:-)

100W, K3...what more does anyone NEED?

I know, I'm running for the cellar!

Gary
Vk4wt
Sent via BlackBerry® from Telstra

-----Original Message-----
From: "Stephen W. Kercel" <[hidden email]>

Date: Tue, 17 Mar 2009 11:21:34
To: <[hidden email]>
Cc: <[hidden email]>
Subject: Re: [Elecraft] Tuning Pulser with K2

Don:

It is a sensible question.

A string of dots sent at nominal weight typically has a duty cycle of
50% off and 50% on. This is the weight to which I keep my keyer
adjusted, and after sending that way for 45 years, I'm used to it.
Typical SSB and CW sent as real characters have a duty cycle closer to
33% on and 67% off. The idea of the tuning pulser is to adjust the
amplifier using a duty cycle similar to what it will encounter in normal
operation.

Now it is true that I could tune the amplifier by temporarily
readjusting the keyer weighting for a 33% duty cycle, ramping up the
speed to about 40 wpm, keying the radio (which requires actually keeping
a hand on the key) and tuning. Then to revert to normal sending, I reset
the keyer to my normal 20-25 wpm, reset the weight to normal weighting,
and then have at it with my newly retuned amplifier. Note however that
I have added about four steps to the tuning and I am in the extremely
awkward position of trying to keep the string of dots going with one
hand on the key and twiddling the knobs on the amplifier with the other.
To make matters worse, I use a WinKey and the N1MM logger; the N1MM
logger preempts the manual controls on the keyer. That means that in
order to reset the weight of the keyer, I need to go to the N1MM's not
especially friendly parameters menu twice, once top set up the pulser
sequence, and then again to restore normal keying.

As you can see, the above is possible in principle, but extremely
awkward in practice.

In contrast, if I connect the keyer and the tuning pulser (which is hard
wired for a 33% duty cycle) to the K2 via a DPDT switch (one pole
selects keyer vs pulser, the other controls the power to the pulser), I
get my tuning pulses with a single flip of the switch. In addition, both
hands are free to twiddle the amplifier, which means I get the tuning
done non-trivially faster. Finally, to get back to normal sending, I
just flip the switch back the other way.

Unlike the Ameritron pulser which costs about $80 and has a lot of
features that are totally unnecessary, this little pulser costs about
$25 for the parts, and a lot less if you have a decently endowed junk
box. This seems a small price to pay to greatly streamline the tuning
process.

73,

Steve
AA4AK

Don Wilhelm wrote:

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Stephen W. Kercel

Re: Tuning Pulser with K2

Gary:

No need to run for the cellar. Your question merits an answer.

Although you may find it hard to credit, I am primarily a QRP guy.

The main reason I need to be able to run in excess of 100 Watts is when
I do short haul (i.e., within my State of Maine) emergency and public
service communications on 80 meters. About 25% of the time, the
propagation conditions are not especially favorable for short haul
communications and it takes about 400 Watts to assure reasonably
reliable statewide coverage on 80 M. Ironically, at these same
unfavorable times for short haul, I can easily be heard in Europe with
100 Watts, or even QRP, on 80 meters.

Why go for an old tube type amp? I already own one; I bought it before
solid state high power amps were available to hams. A fancy new solid
state amp conveniently requires no tuning, but does require an
investment in the $1200-2000 range (if not more) that I can ill afford
(or so the XYL says, and her word is law in these matters) in these
difficult financial times.

73,

Steve
AA4AK

[hidden email] wrote:

> Sure glad I don't own an old amp that needs tuning...:-)
>
> 100W, K3...what more does anyone NEED?
>
> I know, I'm running for the cellar!
>
> Gary
> Vk4wt
> Sent via BlackBerry® from Telstra
>
>

Don Wilhelm-4

Re: Tuning Pulser with K2

In reply to this post by Stephen W. Kercel

Steve,

Not to belabor the point, but if simply tuning the amplifier is the
goal, a 50% duty cycle should get the job done. Assuming the amplifier
is supposed to be linear, tuning it at low power should get the settings
close to the correct point and then a very short tuning time would be
needed at full power. As long as the amplifier has a little bit of
reserve (you are not pushing it to its max), a 33% duty cycle should not
be necessary - I just can't understand why the amp's tuning points would
change with the duty cycle.
If you intend to tune the amp for a lengthy time at full rated power,
then yes, it will be stressed at a 50% duty cycle, but for a reasonably
short tuning period, I just don't see the need.

I would just push a book against the dot paddle and tune away, move the
book when done - no extra steps.

73,
Don W3FPR

Stephen W. Kercel wrote:

> Don:
>
> It is a sensible question.
>
> A string of dots sent at nominal weight typically has a duty cycle of
> 50% off and 50% on. This is the weight to which I keep my keyer
> adjusted, and after sending that way for 45 years, I'm used to it.
> Typical SSB and CW sent as real characters have a duty cycle closer to
> 33% on and 67% off. The idea of the tuning pulser is to adjust the
> amplifier using a duty cycle similar to what it will encounter in normal
> operation.
>
> Now it is true that I could tune the amplifier by temporarily
> readjusting the keyer weighting for a 33% duty cycle, ramping up the
> speed to about 40 wpm, keying the radio (which requires actually keeping
> a hand on the key) and tuning. Then to revert to normal sending, I reset
> the keyer to my normal 20-25 wpm, reset the weight to normal weighting,
> and then have at it with my newly retuned amplifier. Note however that
> I have added about four steps to the tuning and I am in the extremely
> awkward position of trying to keep the string of dots going with one
> hand on the key and twiddling the knobs on the amplifier with the other.
> To make matters worse, I use a WinKey and the N1MM logger; the N1MM
> logger preempts the manual controls on the keyer. That means that in
> order to reset the weight of the keyer, I need to go to the N1MM's not
> especially friendly parameters menu twice, once top set up the pulser
> sequence, and then again to restore normal keying.
>
> As you can see, the above is possible in principle, but extremely
> awkward in practice.
>
> In contrast, if I connect the keyer and the tuning pulser (which is hard
> wired for a 33% duty cycle) to the K2 via a DPDT switch (one pole
> selects keyer vs pulser, the other controls the power to the pulser), I
> get my tuning pulses with a single flip of the switch. In addition, both
> hands are free to twiddle the amplifier, which means I get the tuning
> done non-trivially faster. Finally, to get back to normal sending, I
> just flip the switch back the other way.
>
> Unlike the Ameritron pulser which costs about $80 and has a lot of
> features that are totally unnecessary, this little pulser costs about
> $25 for the parts, and a lot less if you have a decently endowed junk
> box. This seems a small price to pay to greatly streamline the tuning
> process.
>
> 73,
>
> Steve
> AA4AK
>
>
>

Stephen W. Kercel

Re: Tuning Pulser with K2

Don:

Certainly, for A CW guy like me, sliding a book against the dot paddle
would probably work.

However, flipping a toggle switch to get a pulse stream is much more
convenient, especially when the electronics attached to the toggle
switch cost only a few dollars. (Side note: The tuning pulser is one of
the few instances where I have found that home brew is substantially
cheaper than getting "store bought.")

The idea that the tuning point is affected by the duty cycle is claimed
on several different a RF amplifier Web sites. Perhaps they are
mistaken. I must admit that I wonder why a genuinely linear system would
have its tuning point affected by the duty cycle.

Anyway, your suggested fix turned out to be correct. After some
searching through my junk collection, I did find a capacitor of the
proper value, and increased the pulse duration from 12 to 24 ms while
preserving a 33% duty cycle. That completely resolved the "one bar less"
effect. I do find that it takes more than 3 dots for the transmitter to
come up to full power when I change bands and then run the pulser. The
higher the frequency band, the longer the delay, taking only a few dots
to come to full power on 80 meters but several seconds to come up to
full power on 10 meters.

73,

Steve
AA4AK

Don Wilhelm wrote:

> Steve,
>
> Not to belabor the point, but if simply tuning the amplifier is the
> goal, a 50% duty cycle should get the job done. Assuming the amplifier
> is supposed to be linear, tuning it at low power should get the settings
> close to the correct point and then a very short tuning time would be
> needed at full power. As long as the amplifier has a little bit of
> reserve (you are not pushing it to its max), a 33% duty cycle should not
> be necessary - I just can't understand why the amp's tuning points would
> change with the duty cycle.
> If you intend to tune the amp for a lengthy time at full rated power,
> then yes, it will be stressed at a 50% duty cycle, but for a reasonably
> short tuning period, I just don't see the need.
>
> I would just push a book against the dot paddle and tune away, move the
> book when done - no extra steps.
>
> 73,
> Don W3FPR
>
>

dw-4

Re: Tuning Pulser with K2

In reply to this post by Stephen W. Kercel

Stephen,
If you do decide to try a keying relay I can recommend a good source.
I found them through some research this spring.
And they agreed to custom build one for me to replace a cw-keying relay
that I had in a rig which I found too noisy.
Nothing worse than a clicking relay on cw!!!

U.W. Relays and Technology in Chino CA

They are good people!
Duane
N1BBR
--
[hidden email]

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