[Antennas] still troubleshooting rf - may not be antenna??

2002年3月26日 16:35:37 -0600

I am still trying to figure out why I have bad rf distortion on my hf
signals. Here is a message I sent to a couple of local reflectors - maybe
someone can help me figure out another way to stop this rf problem. Many
thanks in advance for suggestions. Also, since this looks like more of an
rf/distortion problem than an antenna problem is there another reflector I
should subscribe to? thanks
de Marty, ag5t
>>>Subject: troubleshooting audio signal distortion

I am looking for some help in trying to figure out what is causing severe
distortion on my hf signals on 15 meters and 10 meters (and possibly other
hf bands).
I recently ran some on-air tests with Lee, WA5QXE to see if changing
anything around at the station would make a difference. We tried both of
my antennas (quad and delta loop), lower power, mike gain at various
positions and a variety of other options such as tuner and no tuner. Even
tried AM transmission. He could not hear me too well on 15 metes so we
switched to 10 meters. Bad distorted signal on everything we tried on both
bands. He thinks it is a microphone problem. I disconnected the microphone
from the rigblaster interface and screwed it directly into the Yaesu
transceiver. Same distortion problem!
Does anyone have an 8-pin hand microphone that I might be able to borrow to
check the signal again? The type of microphone that came with the rig
(Yaesu 747) is a YAESU MH-1 B8 Hand Microphone. I have two chokes on the
microphone cable. The microphone was dropped recently once when some of my
radio equipment accidently fell. I put the microphone back together, but
maybe it broke something that caused it to work poorly? The PTT bar had a
small piece fall off. I don't think this would affect anything, but who
knows?
We discussed line isolators during the on-air testing (such as the rf quick
fix kits seen in qst) but did not think that would solve anything. Lee is
pretty sure it's the microphone that's causing the distortion problems.
Others have also suggested an audio
distortion problem - not necessarily antenna problem.
Should I upgrade to a different microphone? [I've had rough experiences
with desk mics because of relay problems - you press the mike and then have
to tap it or bang it because the audio drops to nothing - then you don't
know if the other station heard you or not because you are too busy banging
the microphone key - anyone else had this problem with desk mikes? maybe it
wasn't a high quality mike?????] Is there a better microphone than the MH-1
that came with the radio? Or does someone know if there is another reason
why my signal is so distorted? Here is the layout of the station - picture
it from left to right.
Power supply, cw key, rotator control box, HF rig (with tuner on top and
low pass filter on top of the tuner), rigblaster, printer, computer,
monitor, coaxes to antenna. The HF rig and tuner and grounded to a heavy
copper line that goes outside and to an 8-foot ground
rod. As I said before, taking the microphone out of the rigblaster and
going directly into the hf rig did not stop the distortion. Does anyone see
any type of pattern that could be causing the distortion? If it's a matter
of the microphone, maybe I could buy a new
Yaesu MH-1 B8 if anyone is still selling them. Thanks for any help and
suggestions. I think if I can solve this distortion problem, it should make
for more enjoyable operating. 
[there was one suggestion that I move the coax away from the monitor and
computer stuff]
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