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HT750 problem
Posted: Wed Aug 30, 2006 6:41 am
by johnny1225
I have a problem with a uhf ht750. Everything seems find until you wiggle the antenna back and forth and it basically looses power and signal from a spectrum analzer. I have resoldered the antenna conector and resolder caps and stuff in the antenna circuit but still the same results. Does anyone know where i should be looking to fix this problem
Thanks in advance
John
Posted: Wed Aug 30, 2006 7:33 am
by Al
You didn't say whether you're testing with the antenna mounted on the HT, but I assume that you are. I've had several VHF antennas fail due to excessive flexure by the user(s). Have you tried changing the antenna?
Posted: Wed Aug 30, 2006 7:35 am
by johnny1225
yes i have change the antenna with a brand new one and it still does the same thing.
Posted: Wed Aug 30, 2006 10:09 am
by Al
I would begin by using a BNC adapter and see if the tx delivers rated power into a 50 ohm load, i.e. service monitor, 30 dB pad or some device that will provide a solid termination. Then you can proceed to troubleshoot the PA/output matching circuit. If the problem shows up on receive as low/lower 12 dB sinad than specifications call for you've got a problem in the matching circuit or pin diode antenna switch. If not, then I'd look around the tx PA.