Coax length on mag mount question

I claim being nuts from driving thru his state Thanksgiving Day. It WAS NOT a holiday.

Actually, I’ve been looking for a post to thank the gentleman for his many informative threads. His gracious attitude. I’m quite pleased he’s livened the place up, thusly.

I guess we got a little too Texan . . . .

Now I’ll go stand in line at the diathermy machine. Sorta like being tasered. My turn (STEEL thread).

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dledinger said:

I’m down for a laugh occasionally, as anyone is.

However, between you and Slowmover you must have nearly 2 dozen posts in this thread, none of which contribute anything other than a waste of time.

I just don’t know why you two picked this thread to spam.

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Because the fix seems obvious.
And, we like you.
(The respect is real).
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Here is prime example of good grounding....Kav just called me, we've been making contacts all day. He hit Omaha clear as a bell and couple others. Reason is he took jumper leads and jumped ground between all equipment and to antenna ground. Cut all static....why? Proper grounding. He complemented his ground plane.

No little wil go can do that.....

dledinger said:

This thread never was about a “fix”.

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There’s a GREAT BIG “why?” in the opening posts. Which implies a solution forthcoming.

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dledinger said:

So...I shortened the coax on a Wilson mag mount, taking off 7’ or so. Checked SWR and everything is great.

Then a few hours later I go for a drive and upon TX I get an RF burn between my hand and face. Ok...turn amp off, check SWR and all is good. Hopped out looked over antenna, then try to TX once more...burned again, but I also notice amp is oscillating (drawing 40 amps SSB when I’m keyed but not talking) and radio display is going bonkers.

So I cruise back home and put in a jumper in extending the feed line to 15/16 feet. Everything back to normal again.

Obvious solution is putting in a hard mount and going on about my business, but I’d like to have somewhat of an understanding what is happening here.

I can only theorize that I have feedline radiation due to the mounting arrangement, and that it’s more of an issue with the shorter coax?

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Obviously, the "why" is in the bold print.

We have been splaining why, for some time.

Check out Maxwell's Antenna books

M0GVZ said:

They really won't because they're so short as to be non-existent as far as the antenna system is concerned and the ground plane as far as the antenna system is concerned is the roof under the mag mount.

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The outside shield is part of the counterpoise. This part is directly connected to the outside shield. So, when currents are travelling over the shield of the coax they are also travelling over that part as well. It is fact, not fiction or opinion. The roof is not the only part of the ground plane either. Whatever body part that is bonded to the roof is an acting part of the ground plane as well, excluding the chassis. I have seen where the addition of this part made enough of a difference that it prevented RF burns on my friend from inside a truck cab where without it the RF burns were still happening. That to me is a difference. I am not an expert to explain how or why. Was it adding to the counterpoise? Was it acting like a trap by soaking up some of the mismatch current? I do not know. I can speculate but a difference was there. We are all in agreement that these radials are short. There is no argument there. Short or not a difference was made. It did NOT remove the common mode currents. It did help reduce them enough that he was no longer getting burned from the RF when he keyed. Ask dledinger how much of the counterpoise he removed. (how much coax he cut off). He said he never had the RF burns prior to cutting the coax. Was the piece too short to make a difference, as far as the antenna system is concerned?

lol....The cheapest fix might be to just replace the coax on that antenna with the correct length. At least you won't have to drill any holes hehehehe

Unit 75 said:

lol....The cheapest fix might be to just replace the coax on that antenna with the correct length. At least you won't have to drill any holes hehehehe

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Yup! "There are some men you just can't get through to"

Even when they clearly ask why?

Hey, as long as your not getting anymore RF burns and your match is good....leave it be.

As far as the thing talking.....I know it does, sure enough. You were coming into the Bam like "Jack The Bear"

dledinger said:

Nothing about that is a “why” implying that I am seeking a fix.

Nor do I think this an issue of running ground wires from equipment. The amplifier and radio are both grounded to the vehicle chassis.

Much like the comparison with “Kav” and his setup. E-skip is providing pretty well ZERO indication that something is working well...it’s just too easy to work DX with CONUS to get anything beneficial from a single good day DXing.

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Grounding cleared out the hash.....proper grounding has everything to do with it.