XV432 Demon Exorcism Operations

[k2qo]

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.

So, here are my questions.

1. Is anyone using their K3 with the XV432 in original as-built condition with good success? No self oscillation or other issues?
2. What mods did you make to tame the demons, if any?

I’m to the point where I need to decide:

A. Fix this one which may take A LONG TIME. But that gives me a K3/XV222 and 432 for 6/222/432 in the rear position of my rover with one headphone, one key, yada yada.
B. Ditch the XV432 and use my FT100D as my 6/222/432. This is a pain because running on 6 and 432 key 222. I’ve run into problems doing this and it really requires that the XV222 be turned OFF except when in use. I suppose I could build a switch that would power up the XV222 when I’ve selected the 28MHz band on the 100D.
C: Build another XV432 and use the current one for spare parts.

Your ideas are greatly welcome.

-- 
73,
Mark K2QO
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[Don Wilhelm-4]

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.
>
>

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[k2qo]

Many have asked and KT4RT said it is OK to make his XV432 mods public, so here you go!

https://www.evernote.com/shard/s88/sh/b4588946-8e2c-4cc5-aee4-a84aaee62655/88ef921572b978f00b25f512e1c693cd

Mark Adams, K2QO
FN03ra
 Sent from my iPad
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