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Problem with K2 transmit quality

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Giulio Pico - IW3HVB

Problem with K2 transmit quality

I have a problem with a K2 who behaves strangely on cw. The note is very
bad, full of distorsions (rf?) but the Tuning continuous carrier is
crisp and clean.....
I don't know if the two are related (I suspect that.... :-) ) but tah
would point to the key !?!.
The other odd thing is that on SSB the modulation is hopping
continuously from very clean and rich to very compressed.....

Any clue?

73 de Giulio IW3HVB
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Don Wilhelm-4

Re: Problem with K2 transmit quality

Giulio,

Can you please describe the distortion? Also, please say whether the
distortion is heard in the sidetone or on a different monitoring receiver.

Does all this happen when operating into a dummy load? Or is it only
when operating into an antenna?

Is this with a hand key? or with paddles? If with paddles, does it
happen with a string of dashes? or a string of dots? or both.

If you have not cleaned your key contacts, that could be the problem.
Put a strip of paper between the key contacts, close the key and extract
the paper - that should clean the contacts.

I cannot comment on the SSB until the CW is corrected.

73,
Don W3FPR

Giulio Pico - IW3HVB wrote:

> I have a problem with a K2 who behaves strangely on cw. The note is very
> bad, full of distorsions (rf?) but the Tuning continuous carrier is
> crisp and clean.....
> I don't know if the two are related (I suspect that.... :-) ) but tah
> would point to the key !?!.
> The other odd thing is that on SSB the modulation is hopping
> continuously from very clean and rich to very compressed.....
>
> Any clue?
>
>
> 73 de Giulio IW3HVB
> ______________________________________________________________
> Elecraft mailing list
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>
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>
>

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Giulio Pico - IW3HVB

Re: Problem with K2 transmit quality

Don Wilhelm wrote:

> Giulio,
>
> Can you please describe the distortion? Also, please say whether the
> distortion is heard in the sidetone or on a different monitoring
> receiver.
>
> Does all this happen when operating into a dummy load? Or is it only
> when operating into an antenna?
>
> Is this with a hand key? or with paddles? If with paddles, does it
> happen with a string of dashes? or a string of dots? or both.
>
> If you have not cleaned your key contacts, that could be the problem.
> Put a strip of paper between the key contacts, close the key and
> extract the paper - that should clean the contacts.
>
> I cannot comment on the SSB until the CW is corrected.
>
> 73,
> Don W3FPR

Instead of a clean note i have a sound like prrrrr prrrrr :-) it is
wide in frequency like when an amplifier is working in a non linear region.

I have it on both antenna and dummy load. Not on the side tone, but on a
second receiver (Tried on HF and 144 MHz with XV144, same result....)

I'm using bencher paddles, on both dot and dashes. The K2 is modified
with external PTT mod.

73 de Giulio IW3HVB
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Don Wilhelm-4

Re: Problem with K2 transmit quality

Giulio,

Do you have anything with a transformer near the K2? Move the K2 at
least a meter away from anything with a transformer and try it again.

If moving it cures the problem, you may either move the device(s) with
transformers or install the VCO Shield Kit in your K2.

73,
Don W3FPR

Giulio Pico - IW3HVB wrote:

> Don Wilhelm wrote:
>
>> Giulio,
>>
>> Can you please describe the distortion? Also, please say whether the
>> distortion is heard in the sidetone or on a different monitoring
>> receiver.
>>
>> Does all this happen when operating into a dummy load? Or is it only
>> when operating into an antenna?
>>
>> Is this with a hand key? or with paddles? If with paddles, does it
>> happen with a string of dashes? or a string of dots? or both.
>>
>> If you have not cleaned your key contacts, that could be the problem.
>> Put a strip of paper between the key contacts, close the key and
>> extract the paper - that should clean the contacts.
>>
>> I cannot comment on the SSB until the CW is corrected.
>>
>> 73,
>> Don W3FPR
>>
>
> Instead of a clean note i have a sound like prrrrr prrrrr :-) it is
> wide in frequency like when an amplifier is working in a non linear region.
>
> I have it on both antenna and dummy load. Not on the side tone, but on a
> second receiver (Tried on HF and 144 MHz with XV144, same result....)
>
> I'm using bencher paddles, on both dot and dashes. The K2 is modified
> with external PTT mod.
>
> 73 de Giulio IW3HVB
> ______________________________________________________________
> 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: 8.0.238 / Virus Database: 270.11.29/2024 - Release Date: 03/26/09 07:12:00
>
>

Jeff kb2m

K3 sub rx matched filters

I'm thinking of upgrading my K3 by adding a KRX3 sub receiver. One of the
things I want to try in the near future is diversity reception. Now, I think
I need a matched pair of filters to operate in diversity mode? Or does this
just pertain to the 5 pole filters? Or, if I already have an 8 pole 1.8
filter would I just have to buy another one ? I tried to search the archives
and there appears to be no keyword search? Thanks in advance for any help
with this....

73 Jeff kb2m

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Steve Ellington

Re: K3 sub rx matched filters

These are good questions and what kind of problems occur when these filters
are not matched?
Steve Ellington
[hidden email]
----- Original Message -----
From: "jeff kb2m" <[hidden email]>
To: <[hidden email]>
Sent: Friday, March 27, 2009 9:41 AM
Subject: [Elecraft] K3 sub rx matched filters

> I'm thinking of upgrading my K3 by adding a KRX3 sub receiver. One of the
> things I want to try in the near future is diversity reception. Now, I
> think
> I need a matched pair of filters to operate in diversity mode? Or does
> this
> just pertain to the 5 pole filters? Or, if I already have an 8 pole 1.8
> filter would I just have to buy another one ? I tried to search the
> archives
> and there appears to be no keyword search? Thanks in advance for any help
> with this....
>
> 73 Jeff kb2m
>
> ______________________________________________________________
> 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: 8.0.238 / Virus Database: 270.11.30/2026 - Release Date: 03/27/09
07:13:00

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Don Wilhelm-4

Re: K3 sub rx matched filters

In reply to this post by Jeff kb2m

Jeff,

The filter offsets should be set the same for diversity reception, and
for that to happen most easily, the filters can be matched. You may
notice a "wush, wush" sound if the offsets are different.
But being practical, the *difference* between the actual offsets of the
filters will be within tens of Hz, and for a wide filter (1.8 kHz or 2.7
kHz), setting the K3 offset values to the average of the two filters
will work fine. OTOH, with narrow filters such as those used for CW,
the two offsets must be closely matched because the difference in the
offsets is a larger percentage of the filter width, and requires matched
filters. It is the difference between the offsets that matters, not the
actual offset value.

Supposedly, the 8 pole filters do not have to be matched (they do not
have offset numbers associated with them), but in practice, they may
have a small offset and some ''tweaking" of the offset values may be
required to eliminate the "wush, wush" sound when using diversity.

73,
Don W3FPR

jeff kb2m wrote:

Steve Ellington

Re: K3 sub rx matched filters

About this "wush, wush" sound....Does this wushing occur as you tune across
stations when in diversity mode or does it just set there and constantly
wush wush? Can't you adjust the compensation for these filters in the menu?
I don't understand why this happens. I had an IC-7800 and played with
diversity recption. Of course there were no physical filter options but
there was no wushing sounds either.

Steve Ellington
[hidden email]
----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "jeff kb2m" <[hidden email]>
Cc: <[hidden email]>
Sent: Friday, March 27, 2009 10:23 AM
Subject: Re: [Elecraft] K3 sub rx matched filters

> Jeff,
>
> The filter offsets should be set the same for diversity reception, and
> for that to happen most easily, the filters can be matched. You may
> notice a "wush, wush" sound if the offsets are different.
> But being practical, the *difference* between the actual offsets of the
> filters will be within tens of Hz, and for a wide filter (1.8 kHz or 2.7
> kHz), setting the K3 offset values to the average of the two filters
> will work fine. OTOH, with narrow filters such as those used for CW,
> the two offsets must be closely matched because the difference in the
> offsets is a larger percentage of the filter width, and requires matched
> filters. It is the difference between the offsets that matters, not the
> actual offset value.
>
> Supposedly, the 8 pole filters do not have to be matched (they do not
> have offset numbers associated with them), but in practice, they may
> have a small offset and some ''tweaking" of the offset values may be
> required to eliminate the "wush, wush" sound when using diversity.
>
> 73,
> Don W3FPR
>
> jeff kb2m wrote:
>> I'm thinking of upgrading my K3 by adding a KRX3 sub receiver. One of
>> the
>> things I want to try in the near future is diversity reception. Now, I
>> think
>> I need a matched pair of filters to operate in diversity mode? Or does
>> this
>> just pertain to the 5 pole filters? Or, if I already have an 8 pole 1.8
>> filter would I just have to buy another one ? I tried to search the
>> archives
>> and there appears to be no keyword search? Thanks in advance for any help
>> with this....
>>
>> 73 Jeff kb2m
>>
>>
> ______________________________________________________________
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>
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Vic K2VCO

Re: K3 sub rx matched filters

In reply to this post by Don Wilhelm-4

Don Wilhelm wrote:

> Supposedly, the 8 pole filters do not have to be matched (they do not
> have offset numbers associated with them), but in practice, they may
> have a small offset and some ''tweaking" of the offset values may be
> required to eliminate the "wush, wush" sound when using diversity.

For what it's worth, I have only a 2.8 kHz filter in my KRX3, and 2.8, 1.0 and 0.4 kHz
filters in my main receiver. Offsets are 0. I use diversity a lot and haven't had any
problems.

Normally I have the bandwidth adjusted to 400 Hz or less when trying to work weak CW
signals. I often find that intelligibility is improved with diversity (on 40 meters I use
a dipole as the main antenna and a vertical as the second rx antenna). It's hard to
describe, but the signal seems to stand out better.

It might be due to the reduction in QSB gained by polarization diversity, or something
else, having to do with noise. I'm not sure.

On 160 I use a 200' wire thrown on the ground as the second rx antenna (main is a
vertical). There is some improvement, but nothing like 40.

On 20, I have a 4-el tribander at 40'. It is *always* better than the vertical by many dB,
so I don't bother with diversity.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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Giulio Pico - IW3HVB

Re: Problem with K2 transmit quality

In reply to this post by Don Wilhelm-4

Don Wilhelm wrote:

> Giulio,
>
> Do you have anything with a transformer near the K2? Move the K2 at
> least a meter away from anything with a transformer and try it again.
>
> If moving it cures the problem, you may either move the device(s) with
> transformers or install the VCO Shield Kit in your K2.
>
> 73,
> Don W3FPR

That was my idea too, but I have no transformers (switching ps and
everything else at 1 mt or more and switched off) and the VCO shielding
is already in place......

Is the tune carrier generated at the same manner of the CW note?

73 de Giulio IW3HVB

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Don Wilhelm-4

Re: Problem with K2 transmit quality

Giulio,

As far as the transmit path is concerned, TUNE is exactly the same as CW.
The activation path through the microprocessor is different.

You might try setting the keying input to HAND and using only the dot
side of the paddles to see if there is some problem with the keying
algorithms inside the microprocessor chip.

Do you have an older K2 that has not been upgraded. Check the value of
RF Board R1 and R2 (near the key jack). They should be 220 ohms.
Remove the left side panel to see the resistors easily.

If it does not happen in TUNE as well as CW, it is most likely in the
keying circuit somewhere - and that is an all digital path until it
reaches the Control Board U8 (this is a DAC) output for the VPWR signal
- but then the TUNE also uses this same output.

I wish I could help more, but you are posing a 'mystery' situation. It
is possible that you have had a failure of some strange kind inside the
firmware chip, but that is a rare occurrance.

You could try a Master Reset, but if you do, write down all your menu
settings including the filter settings because that reset will put them
all back to the default values.

73,
Don W3FPR

Giulio Pico - IW3HVB wrote:

> Don Wilhelm wrote:
>
>> Giulio,
>>
>> Do you have anything with a transformer near the K2? Move the K2 at
>> least a meter away from anything with a transformer and try it again.
>>
>> If moving it cures the problem, you may either move the device(s) with
>> transformers or install the VCO Shield Kit in your K2.
>>
>> 73,
>> Don W3FPR
>>
> That was my idea too, but I have no transformers (switching ps and
> everything else at 1 mt or more and switched off) and the VCO shielding
> is already in place......
>
> Is the tune carrier generated at the same manner of the CW note?
>
> 73 de Giulio IW3HVB
>
>

Henk PA5KT

Re: K3 sub rx matched filters

In reply to this post by Jeff kb2m

The 8 pole filters have no offset. So if you have already an 8 pole
filter you just need to buy one.

73 Henk W6/PA5KT

Quoting jeff kb2m <[hidden email]>:

> I'm thinking of upgrading my K3 by adding a KRX3 sub receiver. One of the
> things I want to try in the near future is diversity reception. Now, I think
> I need a matched pair of filters to operate in diversity mode? Or does this
> just pertain to the 5 pole filters? Or, if I already have an 8 pole 1.8
> filter would I just have to buy another one ? I tried to search the archives
> and there appears to be no keyword search? Thanks in advance for any help
> with this....
>
> 73 Jeff kb2m
>
> ______________________________________________________________
> 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
>
>