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K2/XV-144 with sequencer and big amp

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Bob DeVarney W1ICW

K2/XV-144 with sequencer and big amp

Second question.
I am using my K2 and XV-144 as my EME rig. I take the output of the
transverter key jack and feed it to my sequencer, which then sends the
appropriately delayed signals to my amp ( 750 watts ) and my T/R relays
and preamp at the tower.

My question is this:

Can I slow down the transition from receive to transmit internal to the
K2? Is there a menu option to do so? I could of course use the ptt
signal from my computer to key my sequencer, and then have my sequencer
key the K2, but what if I use the "tune" button on my front panel? That
appears to be instantaneous.
The last thing I want to do is wipe out a very expensive preamp or hot
switch my relays with a 1 kW amp ( in the works )

Thanks in advance,

Bob W1ICW

P.S. I have rediscovered my K2 this year, as a high performance VHF rig
! K2s aren't just for QRP HF any more, I've made over 170 EME QSOs with
my K2, XV-144, 600 watts, and a small ( by EME standards ) array of 16
dBd gain on 2 meters. Bravo to the Elecraft team for coming up with such
a versatile product !

--
Sooner or later, buying crap you don't need with money you don't have grinds to a halt." Jeff A. "
"...the thought of owning a better piece of test equipment is usually sweeter than the reality of it." maynardb

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Don Wilhelm-4

Re: K2/XV-144 with sequencer and big amp

Bob,

No you cannot vary the K2 KEY (or PTT) closure to the onset of RF
timing. It is quite close to 15 ms.

Your best solution IMHO is to first key the sequencer and then use the
output of the sequencer to operate the K2 PTT.

That works for modes except CW. If you are using CW, the K2 always
operates QSK. If you need a PTT input for CW mode, I invite you to look
at the circuit for doing that on my website www.w3fpr.com.
It will delay keying the K2 until the external PTT signal is asserted.

73,
Don W3FPR

On 12/5/2010 7:00 PM, Bob DeVarney W1ICW wrote:

> Second question.
> I am using my K2 and XV-144 as my EME rig. I take the output of the
> transverter key jack and feed it to my sequencer, which then sends the
> appropriately delayed signals to my amp ( 750 watts ) and my T/R relays
> and preamp at the tower.
>
> My question is this:
>
> Can I slow down the transition from receive to transmit internal to the
> K2? Is there a menu option to do so? I could of course use the ptt
> signal from my computer to key my sequencer, and then have my sequencer
> key the K2, but what if I use the "tune" button on my front panel? That
> appears to be instantaneous.
> The last thing I want to do is wipe out a very expensive preamp or hot
> switch my relays with a 1 kW amp ( in the works )
>
>
> Thanks in advance,
>
> Bob W1ICW
>
> P.S. I have rediscovered my K2 this year, as a high performance VHF rig
> ! K2s aren't just for QRP HF any more, I've made over 170 EME QSOs with
> my K2, XV-144, 600 watts, and a small ( by EME standards ) array of 16
> dBd gain on 2 meters. Bravo to the Elecraft team for coming up with such
> a versatile product !
>

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w2bvh

Re: K2/XV-144 with sequencer and big amp

In reply to this post by Bob DeVarney W1ICW

I faced this issue just recently with a K2 and my homebrew 2M
transverter when putting a used 550 W dual 4cx250 power amp into service.

In the long run its best to make the mod to the K2 Don W3FPR outlines on
his web page and I intend to do so some time soon. But as a quick hack
to get on the air I built up a little circuit consisting of a one-shot
and 2 relays that goes in the transverter,

It works as follows: the relay is interposed between the output of the
power attenuator at the I.F. input of the transverter and the first
stage in the transverter's transmit string (the first stage in this case
is the transmit mixer).

When the K2's keyline is asserted (low) it triggers the one-shot which
activates one relay for 35 ms, The relay is driven by a general purpose
npn transistor. While the the relay is driven, it puts a 51 ohm resistor
across the output of the the power attenuator and opens the path
between the power attenuator and the mixer. This prevents the K2's rf
from reaching the transverters transmit mixer for the duration of the
one-shot. After 35 ms have gone by (enough time for the power amps tr
relay to engage) the one-shot times out, reconnecting the power
attenuator to the transmit mixer. The keyline signal also goes to a
second relay via a general purpose npn transistor. That relay drives the
keyline of the power amplifier.

I used an HCF4047 one-shot which happily runs off the 13.5V transverter
power. The relays are a small inexpensive Omron units.

You could probably do something similar to this scheme but *external* to
your XV144 and get similar results.

The upside is that the power amp is not hot switched. The downside is
that the around 20 ms of the first element in the first morse character
is clipped off. Additionally that same morse element does not have a
controlled rise time since it *is* hot switched (in my case at
approximately -4 dBm). So you get a slightly shortened first dit or dah
with a single key click for that element. For me it was a worthwhile
temporary compromise.

It is disappointing that the K2 doesn't have a settable delay for the
onset of rf. A small oversight in an otherwise excellent rig (I've had
mine for over 10 years).

73,
Lenny W2BVH

On 12/5/2010 7:00 PM, Bob DeVarney W1ICW wrote:

Don Wilhelm-4

Re: K2/XV-144 with sequencer and big amp

Lenny,

Yes, this was a design "oversight" for the K2 - I will not call it a
problem, since the focus was for an HF transceiver that would do QSK
operation, and do it quite well.

Unfortunately, that goal is not consistent with those who use
transverters and mast mounted preamps. The parameters relevant to VHF
operators and HF operators are different - and the K2 meets the HF
operators needs quite nicely.

I would steer those VHF operators who need to operate sequencers to the
PTT for CW article on my website (www.w3fpr.com). As far as I know, it
is the best solution for VHF operators with external preamps and
amplifiers to contend with.

The original concept for the K2 being a good QSK CW transceiver for HF
operation breaks down a bit when the use of the K2 for an IF transceiver
for VHF/UHF operation is added. I think my PTT for CW circuit
alleviates some of those problems - but then, I am biased.

One "advantage" for my circuit is that it relies on the activation of
the PTT input to the K2 and not on a key closure. I believe that any
circuit which relies on a key closure will shorten or eliminate the
first CW element - yes, my circuit can do that too, but it is much more
unlikely since the operator must first initiate the PTT line and then
begin keying.

73,
Don W3FPR

On 12/5/2010 9:34 PM, w2bvh wrote:

> I faced this issue just recently with a K2 and my homebrew 2M
> transverter when putting a used 550 W dual 4cx250 power amp into service.
>
> In the long run its best to make the mod to the K2 Don W3FPR outlines on
> his web page and I intend to do so some time soon. But as a quick hack
> to get on the air I built up a little circuit consisting of a one-shot
> and 2 relays that goes in the transverter,
>
> It works as follows: the relay is interposed between the output of the
> power attenuator at the I.F. input of the transverter and the first
> stage in the transverter's transmit string (the first stage in this case
> is the transmit mixer).
>
> When the K2's keyline is asserted (low) it triggers the one-shot which
> activates one relay for 35 ms, The relay is driven by a general purpose
> npn transistor. While the the relay is driven, it puts a 51 ohm resistor
> across the output of the the power attenuator and opens the path
> between the power attenuator and the mixer. This prevents the K2's rf
> from reaching the transverters transmit mixer for the duration of the
> one-shot. After 35 ms have gone by (enough time for the power amps tr
> relay to engage) the one-shot times out, reconnecting the power
> attenuator to the transmit mixer. The keyline signal also goes to a
> second relay via a general purpose npn transistor. That relay drives the
> keyline of the power amplifier.
>
> I used an HCF4047 one-shot which happily runs off the 13.5V transverter
> power. The relays are a small inexpensive Omron units.
>
> You could probably do something similar to this scheme but *external* to
> your XV144 and get similar results.
>
> The upside is that the power amp is not hot switched. The downside is
> that the around 20 ms of the first element in the first morse character
> is clipped off. Additionally that same morse element does not have a
> controlled rise time since it *is* hot switched (in my case at
> approximately -4 dBm). So you get a slightly shortened first dit or dah
> with a single key click for that element. For me it was a worthwhile
> temporary compromise.
>
> It is disappointing that the K2 doesn't have a settable delay for the
> onset of rf. A small oversight in an otherwise excellent rig (I've had
> mine for over 10 years).
>
> 73,
> Lenny W2BVH
>
>
>
> On 12/5/2010 7:00 PM, Bob DeVarney W1ICW wrote:
>> Second question.
>> I am using my K2 and XV-144 as my EME rig. I take the output of the
>> transverter key jack and feed it to my sequencer, which then sends the
>> appropriately delayed signals to my amp ( 750 watts ) and my T/R relays
>> and preamp at the tower.
>>
>> My question is this:
>>
>> Can I slow down the transition from receive to transmit internal to the
>> K2? Is there a menu option to do so? I could of course use the ptt
>> signal from my computer to key my sequencer, and then have my sequencer
>> key the K2, but what if I use the "tune" button on my front panel? That
>> appears to be instantaneous.
>> The last thing I want to do is wipe out a very expensive preamp or hot
>> switch my relays with a 1 kW amp ( in the works )
>>
>>
>> Thanks in advance,
>>
>> Bob W1ICW
>>
>> P.S. I have rediscovered my K2 this year, as a high performance VHF rig
>> ! K2s aren't just for QRP HF any more, I've made over 170 EME QSOs with
>> my K2, XV-144, 600 watts, and a small ( by EME standards ) array of 16
>> dBd gain on 2 meters. Bravo to the Elecraft team for coming up with such
>> a versatile product !
>>
>
> ______________________________________________________________
> 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
>

w2bvh

Re: K2/XV-144 with sequencer and big amp

Hi Don,

The only reason I voiced a bit of disappointment, is Elecraft is known
for their attention to detail when they take on a product design.

When they produced a line of transverters for the K2 I would have
thought they'd upgrade the K2 firmware to add adjustable rf onset
delay. They certainly packed in a lot of other vhf/uhf friendly
features in the K2's firmware to make using the XV's seamless. The XV
transverters have modest power output and I'm sure they must have
realized that an array of different power amps and and preamps would be
connected to them. In fact, there's even instructions in the manual on
how to remove some internal gain in the XV's so tower preamps can be used.

I've got an XV50 and hope to be adding an XV432 probably within the
week, as soon as someone at Aptos gets back to me on whether its worth
spending the extra bux on the crystal oven and/or the high accuracy lo
xtal. So I'm not dissuaded by this missing feature, just a little
irritated.

73,
Lenny W2BVH

On 12/5/2010 9:57 PM, Don Wilhelm wrote:

> Lenny,
>
> Yes, this was a design "oversight" for the K2 - I will not call it a
> problem, since the focus was for an HF transceiver that would do QSK
> operation, and do it quite well.
>
> Unfortunately, that goal is not consistent with those who use
> transverters and mast mounted preamps. The parameters relevant to VHF
> operators and HF operators are different - and the K2 meets the HF
> operators needs quite nicely.
>
> I would steer those VHF operators who need to operate sequencers to
> the PTT for CW article on my website (www.w3fpr.com). As far as I
> know, it is the best solution for VHF operators with external preamps
> and amplifiers to contend with.
>
> The original concept for the K2 being a good QSK CW transceiver for HF
> operation breaks down a bit when the use of the K2 for an IF
> transceiver for VHF/UHF operation is added. I think my PTT for CW
> circuit alleviates some of those problems - but then, I am biased.
>
> One "advantage" for my circuit is that it relies on the activation of
> the PTT input to the K2 and not on a key closure. I believe that any
> circuit which relies on a key closure will shorten or eliminate the
> first CW element - yes, my circuit can do that too, but it is much
> more unlikely since the operator must first initiate the PTT line and
> then begin keying.
>
> 73,
> Don W3FPR
>
> On 12/5/2010 9:34 PM, w2bvh wrote:
>> I faced this issue just recently with a K2 and my homebrew 2M
>> transverter when putting a used 550 W dual 4cx250 power amp into
>> service.
>>
>> In the long run its best to make the mod to the K2 Don W3FPR outlines on
>> his web page and I intend to do so some time soon. But as a quick hack
>> to get on the air I built up a little circuit consisting of a one-shot
>> and 2 relays that goes in the transverter,
>>
>> It works as follows: the relay is interposed between the output of the
>> power attenuator at the I.F. input of the transverter and the first
>> stage in the transverter's transmit string (the first stage in this case
>> is the transmit mixer).
>>
>> When the K2's keyline is asserted (low) it triggers the one-shot which
>> activates one relay for 35 ms, The relay is driven by a general purpose
>> npn transistor. While the the relay is driven, it puts a 51 ohm resistor
>> across the output of the the power attenuator and opens the path
>> between the power attenuator and the mixer. This prevents the K2's rf
>> from reaching the transverters transmit mixer for the duration of the
>> one-shot. After 35 ms have gone by (enough time for the power amps tr
>> relay to engage) the one-shot times out, reconnecting the power
>> attenuator to the transmit mixer. The keyline signal also goes to a
>> second relay via a general purpose npn transistor. That relay drives the
>> keyline of the power amplifier.
>>
>> I used an HCF4047 one-shot which happily runs off the 13.5V transverter
>> power. The relays are a small inexpensive Omron units.
>>
>> You could probably do something similar to this scheme but *external* to
>> your XV144 and get similar results.
>>
>> The upside is that the power amp is not hot switched. The downside is
>> that the around 20 ms of the first element in the first morse character
>> is clipped off. Additionally that same morse element does not have a
>> controlled rise time since it *is* hot switched (in my case at
>> approximately -4 dBm). So you get a slightly shortened first dit or dah
>> with a single key click for that element. For me it was a worthwhile
>> temporary compromise.
>>
>> It is disappointing that the K2 doesn't have a settable delay for the
>> onset of rf. A small oversight in an otherwise excellent rig (I've had
>> mine for over 10 years).
>>
>> 73,
>> Lenny W2BVH
>>
>>
>>
>> On 12/5/2010 7:00 PM, Bob DeVarney W1ICW wrote:
>>> Second question.
>>> I am using my K2 and XV-144 as my EME rig. I take the output of the
>>> transverter key jack and feed it to my sequencer, which then sends the
>>> appropriately delayed signals to my amp ( 750 watts ) and my T/R relays
>>> and preamp at the tower.
>>>
>>> My question is this:
>>>
>>> Can I slow down the transition from receive to transmit internal to
>>> the
>>> K2? Is there a menu option to do so? I could of course use the ptt
>>> signal from my computer to key my sequencer, and then have my sequencer
>>> key the K2, but what if I use the "tune" button on my front panel? That
>>> appears to be instantaneous.
>>> The last thing I want to do is wipe out a very expensive preamp or hot
>>> switch my relays with a 1 kW amp ( in the works )
>>>
>>>
>>> Thanks in advance,
>>>
>>> Bob W1ICW
>>>
>>> P.S. I have rediscovered my K2 this year, as a high performance VHF rig
>>> ! K2s aren't just for QRP HF any more, I've made over 170 EME QSOs with
>>> my K2, XV-144, 600 watts, and a small ( by EME standards ) array of 16
>>> dBd gain on 2 meters. Bravo to the Elecraft team for coming up with
>>> such
>>> a versatile product !
>>>
>>
>> ______________________________________________________________
>> 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
>>
>
>