[Elecraft] KX3 and PX3 with 2m Transverter comments

[Vic Rosenthal 4X6GP/K2VCO]

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 support at elecraft.com. 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