Hello Mike,
The culprit is most likely rf from another band getting into the TS-2000
and causing the problem. Best way to test is to get an HP or similar rf
power meter and hook it to the 1296 antenna cable and SLOWLY run up the
power on the other bands. I have had some serious problems at my QTH from
such things. The hard part is that you have to rotate the antennas to peak
each band up, and you cannot predict where the beam will peak up!
Generally, once you find some rf at the lowest setting, you can then swing
the other antenna around to see the peak. Levels can add from several bands
too!! If you have a good spectrum analyzer, you could use that in place of
the power meter. I have had to run filters on several bands where rf entry
was a problem. I would suspect the 432 PA amp may be hitting 1296. There was
an article in the NEWS newsletter on a good 3rd harmonic TX filter I built
for a 432 KW amp. I saw over 100 dB of insertion loss at 1296.3, and it held
up to 1500 watts at 432. It really knocked the be jeezus out of the 3rd
harmonic, and now 432 and 1296 co exist at the same time. Can your 432
system see the 1296 antenna, or are they vertically spaced on the same mast.
Horizontal spacing is worse than vertical spacing. Signals are louder.
Other bands may just cause out of band problems that can still damage or
kill a front end. A good rx filter will work wonders for that problem.
Levels near 0 dBm can start causing potential damage. If you see anything
even near that level, you need filters real bad!
73
Dave K1WHS
----- Original Message -----
From: "MICHAEL SAPP" <wa3tts@verizon.net>
To: "VHF TEST REFLTR" <vhfcontesting@contesting.com>
Sent: Friday, February 16, 2007 8:38 PM
Subject: [VHFcontesting] TS2000X question
> Hi Folks: Are there any TS2000X owners out there that have had problems
> losing the 2sk2685 HEMT front-end on 1.2 GHz? This is the third time I've
> smoked one at W3KWH during a contest. I'm not sure if it is an ESD
> problem or front end overload. I'm working on a bandpass filter solution
> for the overload possibility but would appreciate any
> comments/expereiences others may have. Thanks in advance. Mike WA3TTS
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting@contesting.com
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