r7 vertical resonates too high
 

my r7 vertical resonates about 450khz too high on ALL bands. This antenna is 15 years old, all dimensions are correct, and it suddenly jumped in resonance after working perfectly for years...nothing has changed physically...just resonates way too high all of a sudden...cap problem in matching network?...something else in the black box?...any ideas?...contact direct at coyotevergreen at q dot com. Thanx. K0SDC

r7 vertical resonates too high
 

On Wed, 3 Sep 2008 05:33:58 +0100, coyotevergreen
wrote:

any ideas?

Radials/counterpoise went south.

73's
Richard Clark, KB7QHC

r7 vertical resonates too high
 

"Richard Clark" wrote in message
...
On Wed, 3 Sep 2008 05:33:58 +0100, coyotevergreen
wrote:

any ideas?

Radials/counterpoise went south.

73's
Richard Clark, KB7QHC

----------

The R7 doesn't use radials or a counterpoise. It is the electrical
equivalent of a 1/2 wave antenna on all bands. That was one of the reasons
that it was so popular.

Like the OP, I tend to agree that the problem is in the black box.

There were several articles published on how to restore the black box to
original specs. Anyone know of their location?

Ed, NM2K

r7 vertical resonates too high
 

Richard Clark wrote:
On Wed, 3 Sep 2008 05:33:58 +0100, coyotevergreen
wrote:

any ideas?

Radials/counterpoise went south.

73's
Richard Clark, KB7QHC

Ill second that, OR, maybe a crudded joint below the point where the
traps start ( remove, clean, and coat with something like Noalox), then
reassemble. Also, see : http://www.iol.ie/~bravo/r7_vertical.htm
and: http://www.telusplanet.net/public/te...craft_trap.htm

for info on R-7 repair-- Jim NN7K

r7 vertical resonates too high
 

Those 5 spokes are a 'capacity hat' loading the bottom half of the 'dipole'.

If the problem is on ONE BAND, I would look at the capacitor assy for that
particular band. They are usually the first item to fail. Your R7 has been
on borrowed time for a few years.

Emil
W9NM

"Edmund H. Ramm" wrote in message
...
In "Ed Cregger"
writes:


[...]
The R7 doesn't use radials or a counterpoise.

Yes it does, those 5 spokes are the counterpoise.

It is the electrical equivalent of a 1/2 wave antenna on all bands.

Lambda 3/8.

[...]

Like the OP, I tend to agree that the problem is in the black box.
There were several articles published on how to restore the black box to
original specs. Anyone know of their location?

http://www.iol.ie/~bravo/r7_vertical.htm

73, Eddi ._._.
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