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KX3 and PX3 with 2m Transverter comments

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GM4JJJ

KX3 and PX3 with 2m Transverter comments

I bought a KX3 and PX3 with a view towards using them with an external high performance transverter for 144MHz (with an IF of 14MHz). My main interest being weak signal operation on VHF. The ability to use the I/Q outputs with a sound card or PX3 and the excellent receiver performance in reviews seemed to indicate this would meet my needs.

Unfortunately it looks like this is not going to work out for me, as the level of radiated noise at VHF from both the PX3 severely masks weak signals, there is also a huge radiated birdie from the KX3 near 144.4MHz.

Turning on the PX3 and listening on 144MHz gives bands of noise every few kHz which mask weak signals in the noise and I can liken it to listening to the 6m band with a Band 1 TV transmitter putting out video sidebands over the band.

Without the PX3 switched on I can hear distant beacons in the noise, but they are buried by the PX3 when it is switched on and plugged in to the KX3. The antenna is 60 feet away from the rigs and is fed by Heliax. Have tried separate supplies for transverter and PX3, running from batteries on KX3, nothing seems to reduce the QRM from the PX3 to an acceptable level.

There also is a huge S9 spurious near 144.4 from the KX3 that is independent of band/freq/mode. Confirmed by listening on another receiver in the shack.

It is so hugely disappointing, I had looked forward to this day, having finally got my rotator and antenna back up on the tower I am faced with looking for another rig to drive the 2m transverter. Unfortunately I don't think it will be Elecraft. Perhaps Elad might be an alternative, but I need to consult the weak signal VHF community first. I will keep the KX3 and PX3 for QRP HF work most likely as selling it at a loss would be a bitter alternative.

On HF where the band noise and signal strengths are much higher I don't find the same problems, though there are still spurious signals shown on the PX3 there. I could live with them I think, but on what is a nice quiet 144MHz band here, the racket from the PX3 is impossible to put up with.

Incidentally I wonder what causes that big birdie near 144.4 from the KX3, and if is it related to the similar one reported on the K3? There doesn't seem to be a lot of commonality between the designs.

Sorry if this sounds like I am trolling, I am not, I love the Elecraft ethos and products, it is just they don't appear to work for my specific needs. Unfortunately it wasn't possible to try before you buy here and I ended up being the guinea pig.

73

David Anderson GM4JJJ
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Vic Rosenthal

Re: KX3 and PX3 with 2m Transverter comments

I don't have either a KX3 or PX3, and my 2m work is limited to FM, but
the problems that you describe could be due to various fixable problems.
For example, some P3s had spur problems due to bad electrical contact
between parts of the enclosure, as well as improperly attached BNC
connectors on the cable between the P3 and K3. I suggest that before you
make any expensive decisions that you contact [hidden email]. I'm
sure they will take your issues seriously.

73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/

Vic

On 27 May 2015 20:26, David Anderson wrote:

> I bought a KX3 and PX3 with a view towards using them with an
> external high performance transverter for 144MHz (with an IF of
> 14MHz). My main interest being weak signal operation on VHF. The
> ability to use the I/Q outputs with a sound card or PX3 and the
> excellent receiver performance in reviews seemed to indicate this
> would meet my needs.
>
> Unfortunately it looks like this is not going to work out for me, as
> the level of radiated noise at VHF from both the PX3 severely masks
> weak signals, there is also a huge radiated birdie from the KX3 near
> 144.4MHz.
>
> Turning on the PX3 and listening on 144MHz gives bands of noise
> every few kHz which mask weak signals in the noise and I can liken it
> to listening to the 6m band with a Band 1 TV transmitter putting out
> video sidebands over the band.
>
> Without the PX3 switched on I can hear distant beacons in the noise,
> but they are buried by the PX3 when it is switched on and plugged in
> to the KX3. The antenna is 60 feet away from the rigs and is fed by
> Heliax. Have tried separate supplies for transverter and PX3, running
> from batteries on KX3, nothing seems to reduce the QRM from the PX3
> to an acceptable level.
>
> There also is a huge S9 spurious near 144.4 from the KX3 that is
> independent of band/freq/mode. Confirmed by listening on another
> receiver in the shack.
>
> It is so hugely disappointing, I had looked forward to this day,
> having finally got my rotator and antenna back up on the tower I am
> faced with looking for another rig to drive the 2m transverter.
> Unfortunately I don't think it will be Elecraft. Perhaps Elad might
> be an alternative, but I need to consult the weak signal VHF
> community first. I will keep the KX3 and PX3 for QRP HF work most
> likely as selling it at a loss would be a bitter alternative.
>
> On HF where the band noise and signal strengths are much higher I
> don't find the same problems, though there are still spurious signals
> shown on the PX3 there. I could live with them I think, but on what
> is a nice quiet 144MHz band here, the racket from the PX3 is
> impossible to put up with.
>
> Incidentally I wonder what causes that big birdie near 144.4 from the
> KX3, and if is it related to the similar one reported on the K3?
> There doesn't seem to be a lot of commonality between the designs.
>
> Sorry if this sounds like I am trolling, I am not, I love the
> Elecraft ethos and products, it is just they don't appear to work for
> my specific needs. Unfortunately it wasn't possible to try before you
> buy here and I ended up being the guinea pig.
>
> 73
>
> David Anderson GM4JJJ

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Jim Brown-10

Re: KX3 and PX3 with 2m Transverter comments

In reply to this post by GM4JJJ

On Wed,5/27/2015 10:26 AM, David Anderson wrote:
> Unfortunately it looks like this is not going to work out for me, as the level of radiated noise at VHF from both the PX3 severely masks weak signals, there is also a huge radiated birdie from the KX3 near 144.4MHz.

Questions and observations. Questions first. Did you build these units
or were they factory assembled? If you built them, dig you carefully
scrape all the tape from the interior parts of the chassis where they
screw together? Not doing so could be part of the problem. To fix this,
you'll have to take it apart and scrape them.

Observation. The KX3 has Pin One Problems at most of the connectors
mounted on the left side -- note that only the Mic and Phones jacks are
screwed to the chassis. My PX3 is out on loan, and I don't remember
whether our not it has the same problem. Any cable connected to a Pin
One Problem becomes an antenna to RX and TX any trash.

Common mode chokes are the band-aid for Pin One Problems. For 2M, the
weapon of choice is one or more Fair-Rite #43 clamp-ons added to the
offending cables. Also, the KX3 chassis should be bonded (short, fat
copper) to the PX3 chassis.

No guarantee that these measures will fix your issue, but I would try
them before giving up. Also, contact Elecraft support and get them
engaged. They talk do lots of people, and chances are they've seen this
before and may know of a fix.

See my website for the tutorials about "The Pin One Problem."

73, Jim K9YC

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GM4JJJ

Re: KX3 and PX3 with 2m Transverter comments

Thanks Jim, yes my PX3 was a kit, and I did do the tape removal and check good electrical contacts as I was sure there could be problems. I don't like the design of the case, would have much preferred a diecast box instead of silly thumbscrews and legs that either are too loose or too tight. As you say having PCB mounted connectors with no connection to the case is part of the problem with radiated noise from the cables.

The KX3 was a factory build, bought in UK from W&S, don't know if they build them in the UK or whether they buy them in already built.

Others have confirmed that the PX3 is noisy on VHF despite all the good tips you have mentioned.

I am resigned to giving up on the KX3 & PX3 for VHF work, which is a pity as otherwise I like it despite it having such poor audio from the built in loudspeaker. OK on headphones, or with a powered speaker though. Trouble is the small neat portable rig quickly becomes a mess of extra cables, filters, copper straps, torroids, copper tape and aluminium foil.

Short of taking the PX3 apart and building it in a proper box along with the KX3 to try and screen things I don't think it is going to work out here. Elecraft have previously commentated that it is switched mode regulators in the PX3 that cause a lot of the noise lines, I had hoped that the gain of the transverter would lift band noise sufficiently to obscure them, but I was unprepared for the PX3 noise actually being quite audible in the receiver, not just visible on the display, which is a showstopper.

I will speak to Elecraft about it though.

Thanks.

73

David Anderson GM4JJJ

>
> Questions and observations. Questions first. Did you build these units or were they factory assembled? If you built them, dig you carefully scrape all the tape from the interior parts of the chassis where they screw together? Not doing so could be part of the problem. To fix this, you'll have to take it apart and scrape them.
>
> Observation. The KX3 has Pin One Problems at most of the connectors mounted on the left side -- note that only the Mic and Phones jacks are screwed to the chassis. My PX3 is out on loan, and I don't remember whether our not it has the same problem. Any cable connected to a Pin One Problem becomes an antenna to RX and TX any trash.
>
> Common mode chokes are the band-aid for Pin One Problems. For 2M, the weapon of choice is one or more Fair-Rite #43 clamp-ons added to the offending cables. Also, the KX3 chassis should be bonded (short, fat copper) to the PX3 chassis.
>
> No guarantee that these measures will fix your issue, but I would try them before giving up. Also, contact Elecraft support and get them engaged. They talk do lots of people, and chances are they've seen this before and may know of a fix.
>
> See my website for the tutorials about "The Pin One .

ejkkjh

Re: KX3 and PX3 with 2m Transverter comments

In reply to this post by GM4JJJ

David,
I also do some 2 meter weak signal, been doing it for many years. I also
have the KX3, PX3 but I use the KX3 internal 2 meter module. I have other 2
meter SSB rigs but find the KX3 to be very good on 2 meters. Your email
made me curious and I did find the signal near 144.4 but I could not find
any other signals being picked up from the PX3. I use the cables that come
with the PX3 and my PX3 is mounted above the KX3. I also have an external
DEMI 222/28 transverter connected to my KX3, again with great results and no
signals picked up from the PX3. Using the PX3 on these bands is great, I
can cover a large area of the bands and monitor everything I want.
Hope it works out for you, good luck, let us know how it works out. 73
Emory WM3M

-----Original Message-----
From: David Anderson
Sent: Wednesday, May 27, 2015 1:26 PM
To: Elecraft Mailer
Subject: [Elecraft] KX3 and PX3 with 2m Transverter comments

I bought a KX3 and PX3 with a view towards using them with an external high
performance transverter for 144MHz (with an IF of 14MHz). My main interest
being weak signal operation on VHF. The ability to use the I/Q outputs with
a sound card or PX3 and the excellent receiver performance in reviews seemed
to indicate this would meet my needs.

Unfortunately it looks like this is not going to work out for me, as the
level of radiated noise at VHF from both the PX3 severely masks weak
signals, there is also a huge radiated birdie from the KX3 near 144.4MHz.

Turning on the PX3 and listening on 144MHz gives bands of noise every few
kHz which mask weak signals in the noise and I can liken it to listening to
the 6m band with a Band 1 TV transmitter putting out video sidebands over
the band.

Without the PX3 switched on I can hear distant beacons in the noise, but
they are buried by the PX3 when it is switched on and plugged in to the KX3.
The antenna is 60 feet away from the rigs and is fed by Heliax. Have tried
separate supplies for transverter and PX3, running from batteries on KX3,
nothing seems to reduce the QRM from the PX3 to an acceptable level.

There also is a huge S9 spurious near 144.4 from the KX3 that is independent
of band/freq/mode. Confirmed by listening on another receiver in the shack.

It is so hugely disappointing, I had looked forward to this day, having
finally got my rotator and antenna back up on the tower I am faced with
looking for another rig to drive the 2m transverter. Unfortunately I don't
think it will be Elecraft. Perhaps Elad might be an alternative, but I need
to consult the weak signal VHF community first. I will keep the KX3 and PX3
for QRP HF work most likely as selling it at a loss would be a bitter
alternative.

On HF where the band noise and signal strengths are much higher I don't find
the same problems, though there are still spurious signals shown on the PX3
there. I could live with them I think, but on what is a nice quiet 144MHz
band here, the racket from the PX3 is impossible to put up with.

Incidentally I wonder what causes that big birdie near 144.4 from the KX3,
and if is it related to the similar one reported on the K3? There doesn't
seem to be a lot of commonality between the designs.

Sorry if this sounds like I am trolling, I am not, I love the Elecraft ethos
and products, it is just they don't appear to work for my specific needs.
Unfortunately it wasn't possible to try before you buy here and I ended up
being the guinea pig.

73

David Anderson GM4JJJ
______________________________________________________________
Elecraft mailing list
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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GM4JJJ

Re: KX3 and PX3 with 2m Transverter comments

Well, some improvements today after encouraging words from forum members. Much opening and closing PX3 case pressing PCBs, reseating connections and cables, moving power leads and suddenly things are 20 dB better. I can now hear the weak beacons with the PX3 switched on. Now to tidy up and try and get a configuration of equipment so that I can test a little better.

That was a close call, I was in the local emporium today and if there had been a certain radio in stock I may well have bought it today!

Thank you all again. My confidence is much restored.

73

David Anderson GM4JJJ

> On 28 May 2015, at 18:08, <[hidden email]> <[hidden email]> wrote:
>
> David,
> I also do some 2 meter weak signal, been doing it for many years. I also have the KX3, PX3 but I use the KX3 internal 2 meter module. I have other 2 meter SSB rigs but find the KX3 to be very good on 2 meters. Your email made me curious and I did find the signal near 144.4 but I could not find any other signals being picked up from the PX3. I use the cables that come with the PX3 and my PX3 is mounted above the KX3. I also have an external DEMI 222/28 transverter connected to my KX3, again with great results and no signals picked up from the PX3. Using the PX3 on these bands is great, I can cover a large area of the bands and monitor everything I want.
> Hope it works out for you, good luck, let us know how it works out. 73
> Emory WM3M
>
> -----Original Message----- From: David Anderson
> Sent: Wednesday, May 27, 2015 1:26 PM
> To: Elecraft Mailer
> Subject: [Elecraft] KX3 and PX3 with 2m Transverter comments
>
> I bought a KX3 and PX3 with a view towards using them with an external high performance transverter for 144MHz (with an IF of 14MHz). My main interest being weak signal operation on VHF. The ability to use the I/Q outputs with a sound card or PX3 and the excellent receiver performance in reviews seemed to indicate this would meet my needs.
>
> Unfortunately it looks like this is not going to work out for me, as the level of radiated noise at VHF from both the PX3 severely masks weak signals, there is also a huge radiated birdie from the KX3 near 144.4MHz.
>
> Turning on the PX3 and listening on 144MHz gives bands of noise every few kHz which mask weak signals in the noise and I can liken it to listening to the 6m band with a Band 1 TV transmitter putting out video sidebands over the band.
>
> Without the PX3 switched on I can hear distant beacons in the noise, but they are buried by the PX3 when it is switched on and plugged in to the KX3. The antenna is 60 feet away from the rigs and is fed by Heliax. Have tried separate supplies for transverter and PX3, running from batteries on KX3, nothing seems to reduce the QRM from the PX3 to an acceptable level.
>
> There also is a huge S9 spurious near 144.4 from the KX3 that is independent of band/freq/mode. Confirmed by listening on another receiver in the shack.
>
> It is so hugely disappointing, I had looked forward to this day, having finally got my rotator and antenna back up on the tower I am faced with looking for another rig to drive the 2m transverter. Unfortunately I don't think it will be Elecraft. Perhaps Elad might be an alternative, but I need to consult the weak signal VHF community first. I will keep the KX3 and PX3 for QRP HF work most likely as selling it at a loss would be a bitter alternative.
>
> On HF where the band noise and signal strengths are much higher I don't find the same problems, though there are still spurious signals shown on the PX3 there. I could live with them I think, but on what is a nice quiet 144MHz band here, the racket from the PX3 is impossible to put up with.
>
> Incidentally I wonder what causes that big birdie near 144.4 from the KX3, and if is it related to the similar one reported on the K3? There doesn't seem to be a lot of commonality between the designs.
>
> Sorry if this sounds like I am trolling, I am not, I love the Elecraft ethos and products, it is just they don't appear to work for my specific needs. Unfortunately it wasn't possible to try before you buy here and I ended up being the guinea pig.
>
> 73
>
> David Anderson GM4JJJ
> ______________________________________________________________
> 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
> Message delivered to [hidden email]