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I found what I think is a Penetrator 500. From old posts I've read it must be the original design as it has only 3 radials and no tuning network, just a uhf connector on the bottom of what looks like the loading coil.

It looks in pretty good shape, just missing one of the top radials and the bottom radials are only 45" long. They look like they were broken off a tv antenna. One end is crimped flat but the other is ragged, not cut like you'd expect. I found a 1975 manual (4 radial) and it lists the radials as 8' 9". Thought I'd fire it up before I go looking for new material.

Anyone know how the short radials will affect swr and anything electrical to check first?

Bruce
KB9OIQ
That's O not 0 IQ

The shorter 45 inch radials will work but they will not provide as much gain as the full 1/4 wave radial set. The antenna will perform better with the longer radials. It is also likely to tune up in a slightly different setting once you lengthen the radials. It will be possible to get a good VSWR match with either set of radials however, you'll probably have to readjust the main radiator length once you change the radials since the antenna you describe does not have an adjustable impedance network at it's base.

Will the 'shortened' radials make a difference? Sure, no idea how much difference, but there will be some. The SWR isn't going to be right, that's almost a 'given'. Would it be worth fixing? That's up to you. If you have what you'd need to fix those radials, sure why not.
- 'Doc

Measure the overall length of the radiator and if it's about 17.5' it's a 1/2 wave Silver Rod not needing radials.
http://www.rigpix.com/antennas/hygai...dpowerplus.htm

New version extended to 5/8
http://www.radioworld.co.uk/~radio/c...na-p-5681.html


19.5' and it's a CLR2
http://www.dxportal.com/stats/conten...ain-clr-2.html

http://home.ptd.net/~n3cvj/clr2.htm

a 'loaded' 5/8 like so many others under 20' which wants the 8' 9" radials like the manual described.

If it's ~22.5' then it's a Penetrator
http://www.cbtricks.com/ant_manuals/..._500/index.htm
but a Penetrator used no base load coil, instead it had a set of aluminum wires on the base which went up the radiator about 16" then back down to the base of the radiator and one to the radials, making a Beta matching network.

Sounds to me like you have one of the first 2.