[Elecraft] XV432 Demon Exorcism Operations

[Don Wilhelm]

Mark,

I cannot identify exactly with your problem statement (K3 locks up), but 
I can give you a few suggestions that may help if you are willing to 
experiment a bit.

First of all, you can try putting a low pass filter between the XV432 
and the K3 low power TX output.  The one I use is a Mini-Circuits 
BLP-30+, but any LPF with a cutoff in the 30 to 36 MHz range should work 
just as well (it would not hurt to include in the coax to the other 
transverters as well if the IF cables are daisy-chained).

The purpose is to eliminate any 432 MHz energy from getting back into 
the K3.  Normally the symptoms are only that the transverter TX output 
is 'fooled' into thinking there is 28 MHz power when actually there is 
very little - but your symptoms seem to be more severe.  It may be worth 
a try in any case.

The 2nd is the power output module in the XV432 itself.  That module was 
changed about 6 months (maybe a year, my memory for dates is short).  
The older module was an SAU82L and the new module is E600120 RA30H4047M1 
High Power Module.  The new metal shielded module prevents self 
oscillation as well as having much better linearity than the older module.

My suspicion is that 432 MHz energy is getting back into your K3 and 
causing the difficulties.
Check your XV432 output connector - it *must* be mounted with the flange 
on the outside of the rear panel.  Also check that the paint has been 
removed from all the XV432 panels where they contact the 2D connectors.  
The is important for proper shielding of the XV432.  While that is 
applicable to all the XVxxx series transverters, it is critical for the 
XV432.

73,
Don W3FPR

On 7/26/2014 8:15 PM, Mark Adams wrote:
> Hi Gang,
>
> I have an XV432 that is giving me fits. While my XV222 works FB with my K3/KXV3 combo, or any other IF rig for that matter, the XV432 has only worked well with my FT817 and 5W drive. While getting stuff together for the August UHF Contest, I now cannot even run the XV432 with the K3 because as soon as I select it, the radio locks up. The display is on but the buttons on the radio do nothing. The only remedy is to put the power cord from the radio and disconnect the I/O cable. Does not matter which of the 2 transverter ends on the cable I use. Again, the XV222 is FB and 432 won’t work.
>
> Some Googling turned up NT4RT who gave a paper at the 2012 SVHFS conference on a bunch of mods for the XV432 to make it work better. Lots of ground via connections, connector rework stuff and loads of changing signal paths by scraping solder mask and cutting traces. All very involved. I have the paper in my Evernote account and will share if you have not seen it, pending NT4RT’s approval. I’m not sure it he wants it to be “public”.
>
> My unit has the errata items performed along with an input filter at the TX1 connection described by a DL ham IIRC.
>
>