[TenTec] Interesting problem and solution
Ken Brown
ken.d.brown at verizon.net
Mon Sep 22 12:41:24 EDT 2003
Hi All,
I have an Omni VI and a Titan. I recently changed the key out to tx
enable cable to what I thought was a better cable, even though it was
working fine. The origninal cable, that worked, was just a plain ten
foot long skinny stereo audio phono plug to phono plug cable ( using
only half of the cable ) and the "better" cable is a six foot Radio
Shack "Gold Series" Audio/Video cable, which appears to be made from 75
ohm coax.
With the "better" cable on 160 meters the transmitter would lock up
whenever the amplifier was putting out more than 500 watts. The watt
meter would indicate power output, and the side tone was gone, unless I
continued to intentionally key the transmitter. Reducing drive from the
Omni, or detuning the amplifier to reduce output to below about 500
watts, would unlock the system. Same thing either to a good dummy load
or to an antenna.
Putting back the cheapo, skinny, longer cable made the problem go away.
At one point I tried a couple of turns of the "better" cable through a
split ferrite core. That did not fix it.
I'm sticking with the cable that works for now. I am interested in
opinions about what is wrong with the "better" cable. Lower capacitance?
Would some additional bypass capacitors on the tx enable in the Omni
make it work with either cable? I have the amplifer and radio grounds
connected with RG-8 outer sheild braid, and am using 1/4 inch Andrew
Superflex Heliax between the Omni and the Titan. It did the same thing
with RG-58. I just used the overkill heliax cable just because it was handy.
Thanks,
Ken N6KB
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