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

Tue May 6 09:14:43 EDT 2014

Hi Peter,
I'll try to play with the crystal (inside the K144XV, right?) In fact, I have, probably, have missed the Elecraft recommendations.
Just got RIGOL DSA815-TG 1.5 GHz Spectrum Analyzer so will be able  to see the LO specrtum purity. Will let VHF folks know the results.
Regarding the MMIC, I was just referring to LO level difference at the mixer LO port.
Will check the relays info.
Thank you so much for your help and ideas!
73 Vic

--------------------------------------------
On Mon, 5/5/14, Peter Torry <peter.torry at talktalk.net> wrote:

 Subject: Re: [Elecraft] Possible bad KREF or K144XV Ref Lock or ???
 To: elecraft at mailman.qth.net
 Date: Monday, May 5, 2014, 8:49 PM

 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.
 > 

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