FW: [Moon-net] Elecraft K2 IF for EME

[Lanier, Robert]

 
Hi everyone,

I am forwarding this partial email thread from the Moon-net list to
everyone here on the Elecraft list in hopes to generate a good
discussion (not a flame war!) on the use of the K2 for weak signal use.
I would appreciate hearing all responses to this subject because I was
considering using the K2 (or maybe the K3?) for weak signal work
someday. What are the major strengths/weaknesses of the K2 in this area,
and what can be done to improve this.

There are some very knowledgable people on this list and your experience
in this area would be most appreciated.

Thanks,
Tony   K4YYZ


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Sergio
Sent: Wednesday, July 12, 2006 4:08 AM
To: D.W. Harms
Cc: Moon Net
Subject: Re: [Moon-net] Elecraft K2 IF for EME

All,

I used to have a K2 and I share the same comments you have mentioned as
well as Shawn's one.  Aside a number of minor things, I was mostly
annoyed by the bad ripple of the IF filters too, which is not a trivial
thing. They kept the filters area still at a 'very kit level' , maybe it

would have been better to put some extra effort there.

Another major draw back for me it was the 10Hz step tuning, which with
the very tight DSP set at maybe 50Hz BW it didn't really ensure a proper

operation in CW/weak signals. Yes one could eventually set the RIT as
the 'fine resolution tune' but then the split function was lost and, in
my case, I could not compensate the doppler anymore thus being obliged
to use another rig in TX...

This is just to report my practical experience, it is not my intention
to bias any soul. Aside this, I also have to report that building the
radio was definitely a nice experience bringing a lot of satisfaction
and excitement during its progression.

Sergio IK2MMB


D.W. Harms wrote:
> Hi Don e.e.
>
> Besides my home mde transceiver I have the K2 with a built in DEM
> transvertor (144-28 ECK) in use since Januari 2004.
> In combination with the transvertor it slightly outperforms my home
made
> transceiver. I can highly recommend the radio!
>
> There are only two things that bother me:
>
> 1. The throughput gain on 28 MHz seems to be low. I made a seperate
output
> on the rig to bring the 28 MHz signal to my Drake R7/Tr7 combination
and I
> have obviously more signal there. This of course could influance the
> overall noise floor...
> The K2 really marvels at the lower HF-bands, but the front-end filters
on
> 28 MHz are not that good. That is probably why the excellent
strong-signal
> behaviour for which the K2 is well-known, is not too obvious on 28
MHz. I
> sometimes think about replacing the frontend filters, or to change the
IF
> to 14 MHz.
>
> 2. The IF-filter seems to produce some ripple, as reported by another
ham
> here on moonnet. Of course this is a killer in weak signal work! I
have
> not noticed it myself, but heard others (PA0CHN) complain about it.
>
> It was fun building the radio during the x-mas holidays together with
my
> youngest son. So if you are looking for a "heatkit-like" project, then
go
> for it!
> It is a superb radio for portable work. I use it in combination with a
> 300W mosfet amp for MS-work and have good experiences. It is probably
much
> better than the average portbale multi-multi band rice-boxes...
>
> I am not too sure yet if it is the best radio for weak-signal EME
work. I
> have to  do some more investigation. It is hard to judge given the
fact
> that I have lots of urban noise, something that EVERY radio would
suffer
> from hi!
>
> I also saw a remark about microphones. Well, I have used the K2 wit
both
> an electret and a MD-microphone. Both worked well, though you should
not
> expect HIFI reports...  But then again, I am no fone-fan so I dont
bother
> too much...
>
> VY 73, Dick PA2DW
>
>
>
>> Is anyone using the Elecraft K2 transceiver on 28 MHz as the "IF" in
an
>> EME system?  If so I would appreciate your evaluation of the K2 in
terms
>> of  "receive" capability of weak EME cw signals. Please reply direct
to
>> <[hidden email]>
>>
>>
>> _______________________________________________
>> Moon-Net posting and subscription instructions are at
>> http://www.nlsa.com/nets/moon-net-help.html
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[zeke7237]

I actually posted the start of this thread here a couple of days ago ..

They've got valid points for EME, but they don't apply so much to
typical VHF/UHF contest work. I've only got one rove in using the
Elecraft stuff .. the low band station worked great once I got the
right combination of IF cables and Ts. Strong signal performance was
great, conditions were so poor that there wasn't much weak signal
around :(

The high band station ended up using an IC-706, but that was a failure
in the 144-28 xverter .. we used the K2 as the bandswitch, because I
had integrated everything from 903-10G using a custom-mapped KRC2

I'll have more to say in the fall after I get more experience and
tweak out some bugs, but so far I like it

de w1rt/john

On 7/13/06, Lanier, Robert <[hidden email]> wrote:

>
> Hi everyone,
>
> I am forwarding this partial email thread from the Moon-net list to
> everyone here on the Elecraft list in hopes to generate a good
> discussion (not a flame war!) on the use of the K2 for weak signal use.
> I would appreciate hearing all responses to this subject because I was
> considering using the K2 (or maybe the K3?) for weak signal work
> someday. What are the major strengths/weaknesses of the K2 in this area,
> and what can be done to improve this.
>
> There are some very knowledgable people on this list and your experience
> in this area would be most appreciated.
>
> Thanks,
> Tony   K4YYZ
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Sergio
> Sent: Wednesday, July 12, 2006 4:08 AM
> To: D.W. Harms
> Cc: Moon Net
> Subject: Re: [Moon-net] Elecraft K2 IF for EME
>
> All,
>
> I used to have a K2 and I share the same comments you have mentioned as
> well as Shawn's one.  Aside a number of minor things, I was mostly
> annoyed by the bad ripple of the IF filters too, which is not a trivial
> thing. They kept the filters area still at a 'very kit level' , maybe it
>
> would have been better to put some extra effort there.
>
> Another major draw back for me it was the 10Hz step tuning, which with
> the very tight DSP set at maybe 50Hz BW it didn't really ensure a proper
>
> operation in CW/weak signals. Yes one could eventually set the RIT as
> the 'fine resolution tune' but then the split function was lost and, in
> my case, I could not compensate the doppler anymore thus being obliged
> to use another rig in TX...
>
> This is just to report my practical experience, it is not my intention
> to bias any soul. Aside this, I also have to report that building the
> radio was definitely a nice experience bringing a lot of satisfaction
> and excitement during its progression.
>
> Sergio IK2MMB
>
>
> D.W. Harms wrote:
> > Hi Don e.e.
> >
> > Besides my home mde transceiver I have the K2 with a built in DEM
> > transvertor (144-28 ECK) in use since Januari 2004.
> > In combination with the transvertor it slightly outperforms my home
> made
> > transceiver. I can highly recommend the radio!
> >
> > There are only two things that bother me:
> >
> > 1. The throughput gain on 28 MHz seems to be low. I made a seperate
> output
> > on the rig to bring the 28 MHz signal to my Drake R7/Tr7 combination
> and I
> > have obviously more signal there. This of course could influance the
> > overall noise floor...
> > The K2 really marvels at the lower HF-bands, but the front-end filters
> on
> > 28 MHz are not that good. That is probably why the excellent
> strong-signal
> > behaviour for which the K2 is well-known, is not too obvious on 28
> MHz. I
> > sometimes think about replacing the frontend filters, or to change the
> IF
> > to 14 MHz.
> >
> > 2. The IF-filter seems to produce some ripple, as reported by another
> ham
> > here on moonnet. Of course this is a killer in weak signal work! I
> have
> > not noticed it myself, but heard others (PA0CHN) complain about it.
> >
> > It was fun building the radio during the x-mas holidays together with
> my
> > youngest son. So if you are looking for a "heatkit-like" project, then
> go
> > for it!
> > It is a superb radio for portable work. I use it in combination with a
> > 300W mosfet amp for MS-work and have good experiences. It is probably
> much
> > better than the average portbale multi-multi band rice-boxes...
> >
> > I am not too sure yet if it is the best radio for weak-signal EME
> work. I
> > have to  do some more investigation. It is hard to judge given the
> fact
> > that I have lots of urban noise, something that EVERY radio would
> suffer
> > from hi!
> >
> > I also saw a remark about microphones. Well, I have used the K2 wit
> both
> > an electret and a MD-microphone. Both worked well, though you should
> not
> > expect HIFI reports...  But then again, I am no fone-fan so I dont
> bother
> > too much...
> >
> > VY 73, Dick PA2DW
> >
> >
> >
> >> Is anyone using the Elecraft K2 transceiver on 28 MHz as the "IF" in
> an
> >> EME system?  If so I would appreciate your evaluation of the K2 in
> terms
> >> of  "receive" capability of weak EME cw signals. Please reply direct
> to
> >> <[hidden email]>
> >>
> >>
> >> _______________________________________________
> >> Moon-Net posting and subscription instructions are at
> >> http://www.nlsa.com/nets/moon-net-help.html
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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[Don Wilhelm-3]

Tony,

I do not have any real experience with weak signal VHF work, but I do have
some comments about the K2 on a technical basis that may help in your
decisions.

I would be interested to know what the filter width was in use that
generated those comments as well as the serial number of the K2 that was
being used for that evaluation.  Some of those deficiencies have been
addressed and corrected along the K2's migration progress.

The facts as I know them - the K2 SSB filter has very little ripple in the
passband.  The filter crystal specs (for all the IF crystals) were improved
between Elecraft and the crystal vendor and the improved crystals have been
in K2s since SN 2560.

Secondly, the variable width (CW) filter on the RF board presents a smooth
single-nosed passband if the filter width is set to 1000 Hz or less.  Wider
passbands do tend to break up into multiple peaks which may be troublesome
to some applications, but that is the downside to attemting to use a filter
designed for best response in the 400 to 600 Hz width range at a very wide
setting - it works OK for SSB voice reception, but it certainly is not an
optimum filter shape.

Yes, the K2 is limited to 10 Hz steps - that is just part of the design
compromises that were deemed acceptable  Even RIT does not circumvent this
limitation - the firmware controls the steps and RIT works through the
firmware.

For Satellite work, several folks have previously commented that the biggest
downside for the K2 is the fact that the frequency cannot be changed while
transmitting.  That may not be a factor in many situations but where the
transmit frequency must be changed to compensate for doppler, all I can say
is that the K2 was not designed to do that task.  Maybe the K3 or K? (if it
ever gets into the product plan) will address that problem.

The 28 MHz bandpass is broader than the others, and could possibly be
improved if designed for a more narrow passband, but for HF use, that
bandpass filter must be rather wide - as it is now on the K2, the speced 10
meter band is 28.0 to 28.8 MHz rather than going up to 29.7, so some
compromises have already been put in place.  The one nice thing about the K2
is that it can be changed to better meet the needs of a particular group of
folks if desired - the network is nothing more than a double tuned bandpass
filter, and the filter components can be altered for a more narrow peak if
that is desirable.

73,
Don W3FPR

> -----Original Message-----
>
> I am forwarding this partial email thread from the Moon-net list to
> everyone here on the Elecraft list in hopes to generate a good
> discussion (not a flame war!) on the use of the K2 for weak signal use.
> I would appreciate hearing all responses to this subject because I was
> considering using the K2 (or maybe the K3?) for weak signal work
> someday. What are the major strengths/weaknesses of the K2 in this area,
> and what can be done to improve this.
>
> There are some very knowledgable people on this list and your experience
> in this area would be most appreciated.
>
> Thanks,
> Tony   K4YYZ
>

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Elecraft web page: http://www.elecraft.com

[Karl Larsen]

        Hi  Don  and  the  others.  I'm an EE and here are some things to
   consider.  For  EME  the K2 will be driving the transmitter via a high
   level  mixer   and  the receiver will be a converter built to tune 432
   MHz. If I were doing it I would mix down to 14.000 to 14.350 MHz. This
   makes the good things about the K2 fully functional :-)
       The S/N is a total function of the first RF stage of the converter
   at  432  MHz  IF  the  stage  gain is 15 DB or more. If you don't have
   enough gain you can put an IF stage in the converter.
        The  10 HZ tuning step is kind of odd to me. My At-Sprint 3 has a
   DDS  frequency  generator  that  is of a step type. It is around 10 Hz
   too.  My  Yaesu  radios  tune smoothly and the FT-817 has been a great
   radio  for EME work. It is very common now. The 817 has a little phase
   lock loop noise that the gain of the converter masks with signal+noise
   from  432 MHz. And you can buy the ultra stable crystal oscillator kit
   for the 817 that makes it very stable. The standard crystal oscillator
   is not good enough :-)
   73 Karl K5DI
   Don Wilhelm wrote:

Tony,

I do not have any real experience with weak signal VHF work, but I do have
some comments about the K2 on a technical basis that may help in your
decisions.

I would be interested to know what the filter width was in use that
generated those comments as well as the serial number of the K2 that was
being used for that evaluation.  Some of those deficiencies have been
addressed and corrected along the K2's migration progress.

The facts as I know them - the K2 SSB filter has very little ripple in the
passband.  The filter crystal specs (for all the IF crystals) were improved
between Elecraft and the crystal vendor and the improved crystals have been
in K2s since SN 2560.

Secondly, the variable width (CW) filter on the RF board presents a smooth
single-nosed passband if the filter width is set to 1000 Hz or less.  Wider
passbands do tend to break up into multiple peaks which may be troublesome
to some applications, but that is the downside to attemting to use a filter
designed for best response in the 400 to 600 Hz width range at a very wide
setting - it works OK for SSB voice reception, but it certainly is not an
optimum filter shape.

Yes, the K2 is limited to 10 Hz steps - that is just part of the design
compromises that were deemed acceptable  Even RIT does not circumvent this
limitation - the firmware controls the steps and RIT works through the
firmware.

For Satellite work, several folks have previously commented that the biggest
downside for the K2 is the fact that the frequency cannot be changed while
transmitting.  That may not be a factor in many situations but where the
transmit frequency must be changed to compensate for doppler, all I can say
is that the K2 was not designed to do that task.  Maybe the K3 or K? (if it
ever gets into the product plan) will address that problem.

The 28 MHz bandpass is broader than the others, and could possibly be
improved if designed for a more narrow passband, but for HF use, that
bandpass filter must be rather wide - as it is now on the K2, the speced 10
meter band is 28.0 to 28.8 MHz rather than going up to 29.7, so some
compromises have already been put in place.  The one nice thing about the K2
is that it can be changed to better meet the needs of a particular group of
folks if desired - the network is nothing more than a double tuned bandpass
filter, and the filter components can be altered for a more narrow peak if
that is desirable.

73,
Don W3FPR


 

-----Original Message-----

I am forwarding this partial email thread from the Moon-net list to
everyone here on the Elecraft list in hopes to generate a good
discussion (not a flame war!) on the use of the K2 for weak signal use.
I would appreciate hearing all responses to this subject because I was
considering using the K2 (or maybe the K3?) for weak signal work
someday. What are the major strengths/weaknesses of the K2 in this area,
and what can be done to improve this.

There are some very knowledgable people on this list and your experience
in this area would be most appreciated.

Thanks,
Tony   K4YYZ

   
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[Nick Waterman]

Don Wilhelm wrote:
> Yes, the K2 is limited to 10 Hz steps - that is just part of the design
> compromises that were deemed acceptable

... and considering most rigs are only accurate to about 30-50Hz, I'm
surprised anyone cares.

> For Satellite work, several folks have previously commented that the biggest
> downside for the K2 is the fact that the frequency cannot be changed while
> transmitting.

Presumably if you want to get cunning, you could have your software
change frequency in between every CW character, or in every word-gap in
VOX mode. Is that not enough? I've not worked EME and barely worked
Satellite, but I'd have imagined this was only an issue in data modes
with particularly long sync periods... which would sound like a silly
thing to use for doppler-cursed modes anyway?

What sort of modes do people usually use for EME?

--
"Nosey" Nick Waterman, G7RZQ, K2 #5209.
use Std::Disclaimer;    [hidden email]
All the good ones are taken. -- Harris's Lament
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[Geoffrey Mackenzie-Kennedy-2]

Hi Tony,

Although I have not worked EME but only listened to signals reflected by the
moon, since the late 1950s I have been involved in weak signal work on 6m -
including a project (from Canada) in the late '60s to work crossband 6m / 4m
across the Atlantic. From this, if I was going to use the K2 as an IF two
considerations come to mind. (1) The internal spurii of the K2's receiver.
It is possible that adequate gain in the converter would put many of these
below the system's noise floor, but certainly not the birdie around 14.360
MHz. Too much converter gain breeds other problems as you appreciate. (2)
The ripple exhibited by the K2's IF filter which IMHO is a bit too large in
my K2 #3255 for weak signal work.

The converter's IF block should also exhibit good selectivity to avoid the
possible introduction of noise at the K2's image frequency. I have not
checked this on 20m.  On 40m a higher order response of the K2 sometimes
gives me trouble with BC stations below the band.

73,
Geoff
GM4ESD


----- Original Message -----
From: "Lanier, Robert" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, July 13, 2006 9:42 PM
Subject: [Elecraft] FW: [Moon-net] Elecraft K2 IF for EME



Hi everyone,

I am forwarding this partial email thread from the Moon-net list to
everyone here on the Elecraft list in hopes to generate a good
discussion (not a flame war!) on the use of the K2 for weak signal use.
I would appreciate hearing all responses to this subject because I was
considering using the K2 (or maybe the K3?) for weak signal work
someday. What are the major strengths/weaknesses of the K2 in this area,
and what can be done to improve this.

There are some very knowledgable people on this list and your experience
in this area would be most appreciated.

Thanks,
Tony   K4YYZ





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