[Elecraft] XV222 RX is Dead, Need Advice

Fri Sep 18 09:58:16 EDT 2020

Mike,

I’ve done some of these mods, but not all.

I replaced the MAR6 this morning and it now hears a little better, but the S-meter on the K3 is not moving. Q3 is next.

AND I JUST REMEMBERED!!!  When I was setting up the rover before the contest, I was keying all the equipment with the antennas attached to check power output, listen to local beacons, etc. The XV222 was receiving OK. I then transmitted and in a few seconds blew the 5A fuse in my WestMountain Radio distribution block. I intended on commenting it to a 10A PP connector but “missed”. I replaced the fuse and went roving. 

I wonder whether maybe that caused some TX energy to get back into the RX circuit? Oh well, the MAR6 is replaced and I’ll get a new ATF. 

The crazy thing is that I did not think of this until last night when I had everything on the bench. 

73,
Mark K2QO
FN03ra

> On Sep 17, 2020, at 10:54 PM, M Cresap <m.cresap at yahoo.com> wrote:
> 
> Hi Mark
> 
> Yes, the XV432 transverter needed a few fixes to work reliably. NT4RT wrote an excellent article on how to improve the performance of the XV432 (which I see you have found already). My XV432 is extensively modified with my own fixes, most of NT4RT's fixes, and K9YC's recommended "Pin 1 problem" fixes (i.e. rebuild the back panel). 
> 
> For the XV222, the first thing I would do to hook up your noise generator to the RF input and try to adjust R13 for about 250 mV on TP2. See if that improves your ability to receive the noise generator. I found that the gain varies a LOT as R13 is adjusted. Be careful not to mistakenly tweak R10, which is nearby! Don't ask how I know that :-(
> 
> Let me know if that helps.
> 
> 73, Mike, W3IP
> 
> On Thursday, September 17, 2020, 10:29:59 PM EDT, Mark Adams <msadams60 at gmail.com> wrote:
> 
> 
> Thanks Mike. I built this along with the XV432 a LONG time ago :-) The 432 unit had loads of issues. My rover partner, a EE grad from 1964 who designed military radios and antennas for a living was not impressed with either of these transverters, especially the XV432. For a hobby, he checks the math in QEX articles. One time he told me that the author mis-applied Maxwell’s equation and he ran his own set of differential equations to prove the point. 
> 
> On to the my results:
> 
> 
>> On Sep 17, 2020, at 9:44 PM, M Cresap <m.cresap at yahoo.com <mailto:m.cresap at yahoo.com>> wrote:
>> 
>> Take off the top cover of the transverter, check the voltage between TP2 and ground (should be between 200 to 275 millivolts). That measures part of the source voltage of Q3, the first receiver amplifier. 
> 
> 
> 65mV
> 
> 
>> 
>> Find R16 (a 120 ohm resistor) and measure the voltage to ground on each side of the resistor. One side should be 12 volts, the other should be about 5 volts. That measures the series dropping resistor for U1, the second receiver amplifier. R16 will normally be very warm to the touch.
> 
> 
> 13.8 and 4.9V
> 
> 
>> 
>> If those measurements are correct, the problem is most likely elsewhere. 
>> 
>> You can check the condition of the local oscillator by measuring the voltage between TP1 and ground. It should be between 1.0 and 1.5 volts. 
> 
> 
> 0.92V
> 
> 
> Additionally, TP1 is 0.76V, not the minimum 1V.
> The output pin of U1 is 0V, not 3.0-6.0V.
> 
> 
> 
> 
>> 
>> 
>> 
>> 
>> On Thursday, September 17, 2020, 8:58:35 PM EDT, k2qo <msadams60 at gmail.com <mailto:msadams60 at gmail.com>> wrote:
>> 
>> 
>> During the recent September VHF contest I could only hear the absolute
>> strongest local stations on the XV222/K3 in my rover. It worked FB in June.
>> My XV432 worked just OK as usual. Stations told me I was the loudest signal
>> on the 222 band so the TX side is fine. 
>> 
>> I put it on the bench and connected my Elecraft N-Gen. When turned on I
>> could barely detect an increase in noise. Tried the same on my XV432 and it
>> went from S0/1 to a solid S9.
>> 
>> I'm guessing that I somehow blew up U1 (an ERA6) and/or Q3 (an ATF 34143). I
>> don't have a good scope, RF generator, or RF voltmeter but kinda think
>> replacing both will fix my XV. A bad relay is an option too.
>> 
>> Thoughts? I'd like to fix it to have for a spare as I plan on moving
>> non-BigE transverters for 222 and 432. 
>> 
>> 73,
>> Mark K2QO
>> NF2RS/R for the September VHF 
>> 
>> 
>> 
>> --
>> Sent from: http://elecraft.365791.n2.nabble.com/ <http://elecraft.365791.n2.nabble.com/>
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> 
> 