[Yaesu] Flaky PTT switch on MD100 Mic

Sat May 1 15:47:37 EDT 2010

Hi All,
For awhile now I've had an intermittent "chattering" problem when 
transmitting with the FT-2000. It was rapidly switching between TX/RX 
when transmitting. At first I thought it was a SWR problem causing it 
to trip as it seemed to get a little better if I cut back on the mic 
gain/processing. But all indications were that the MFJ auto tuner was 
doing it's job with the 88 foot non-resonant dipole, and I'd NEVER see 
anything on the rig's SWR meter.
Finally it got so bad that anytime I tried to check into a net, net 
control said I was breaking up so badly he couldn't copy me.
In doing further checks, it turned out that if I used the MOX switch, OR 
locked the Mic switch into the TX mode, all was OK. Eureka! Problem 
ONLY on the PTT switch. I disassembled the mic (easily done), squirted 
some Deoxit D5 (my contact cleaner of choice) on all the switches and 
worked them a few times. Reassembled the mic and tested it, no further 
problems. (BIG SMILE)
NOTE 1: This rig will be three years old later this summer, as I use it 
primarily as a receiver for beacon work and SWLing, it only gets 
transmitted on a few times a month (and usually Field Day each year). 
This is the FIRST problem I've ever experienced with the rig, and 
undoubtedly this problem probably wouldn't have occurred if the rig got 
more use to keep the contacts clean. I'm still VERY pleased with my 
purchase, it's the finest rig I've ever owned. Up to the time I bought 
it, I invariably purchased used equipment that I had to do extensive 
work on to get "right".
NOTE 2: The PTT switches in the MD-100 are the cheap variety you often 
see in old VCR's, etc. 
-- 
73 de Phil, KO6BB
http://ko6bb1.multiply.com/ (My OTR Blog)
http://www.qsl.net/ko6bb/ (Web Page)
RADIOS:
Yaesu FT-2000 Xceiver for "hamming" and LF Beacons.
TenTec 1254, W9GR DSP, SEATTY for NAVTEX Reception.
Zenith Royal 7000-1 Transoceanic Portable.
6 Hz Audio filter, Tunable LF Pre-amp for NDBs.
ANTENNAS: 88' Ladder-Line fed dipole and two "Mini-Whips.
Merced, Central California, 37.3N 120.48W CM97sh