[Elecraft] Possible bad KREF or K144XV Ref Lock or ???

[Peter Torry]

Hi Victor,

Thanks for the update - most interesting.

I am using the K144XV  in conjunction with the REFLock and found that 
the crystal and its grounding was the problem. May I suggest that you 
experiment with earthing the crystal can as suggested by Elecraft and / 
or changing out the crystal.
As far as small RF relays are concerned I use the Teledyne TO5 can type 
732 that will fit easily in the enclosure and have reasonable isolation 
across the contacts.
I have not found any problems using MMICs and will continue to use 
them.  In fact I use a PGA103 in my masthead preamp without a problem.

Hope the above is of some help.

73

Peter
G3SMT


On 04/05/2014 09:28, Vic Goncharsky via Elecraft wrote:
> Hi Harry,
> Hope the info that follows will be useful.
> I have made some research of how to make the internal K144XV Elecraft transverter be useful in contests.
> Originally it was almost useless due to many parasitics all across the band even from S9 signals.
> The stronger – the worse and there were a lot of them even here in KN29AU.
> So in July, last year, during IARU R1 3-rd subregional VHF contest, the band was full of clones. HI HI.
>
> Comparying the schematics of both internal and external Elecraft 144 transverters shows three major differences that could have caused the different dynamic performance of the internal one.
> Firstly - the usage of three diode switching components in the Front-End chain up to the ADEX mixer.
> Secondly - usage of MMIC instead of BFR96 in the LO amplifier stage.
> Thirdly - the K144XV PHASE LOCK BOARD
>
> Here are some findings and possible solutions.
> 1.Remove (do NOT install) the K144XV PHASE LOCK BOARD!
> In this case transverter is using just its own Xtal generator and spirious signals caused, possibly, by leakage from the synthesizer are gone.
> 2. Bypass the input diode T/R input switch by using separate receiving path. Remove the shorting block from pin1-2 of the P3 connector and connect separate coax to pin2 – RF, pin3 – ground.
> This requires adding some front-end filtering and RF relays in PA, LNA or wherever you like.
> (I would have prefer to get rid of all diode switching in RX RF path but have no idea of RF relays small enough to fit into K144XV box).
> I have tested this setup in September during IARU R1 VHF championship and compared to July's event it looked like day and night.
>