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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