Old timer here ...

I remember once building a DDRR antenna (before I learned what a joke that idea was) for 20m on the floor on my apartment using just wire for both the ring and the "ground plane". It was essentially a vertical 10 inches or so of wire with a quarter wave parallel wire transmission line configured in a circle to "match" it to my SB-101 barefoot. I somehow managed to make some stateside CW contacts with it, but I had to wear thick gloves to avoid the severe RF burns (as in black holes deep into my fingers) from the hand key. Needless to say it only lasted one evening.

73,
Dave   AB7E




On 3/11/2014 4:24 PM, Joe Subich, W4TV wrote:

> Is having the Microham directly on top of the KAT500 Tuner with the
> microphone cable almost touching the RF out a potential issue? If so,
> this might be an easy fix for now.

No, not if your antenna system is properly designed and there is no
common mode current on the outside of the feedline.  If you do have a
common mode issue, arrangement of equipment may make minor differences
as the effective line length changes but rearranging equipment is not
going to *fix* an antenna system issue.

Old timers will recognize common mode as "getting bit by the mic" or
getting a "tickle" when touching metal portions of the key <G>.  That
was an extreme level of common mode RF (several volts).  Just a volt
or two can seriously upset modern solid state equipment or impact low
level microphone audio (a dynamic mic has a level generally less than
20 mV).

73,

   ... Joe, W4TV

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