Unadilla 40m trap refurbishment by Nick G0VQO

As I find myself with spare time on my hands during lockdown.

I decided to pass some time resurrecting an 80m/40m  trapped dipole that I had used some years ago but took out of service as the traps had deteriorated.

On inspection I could see that the bolt fixing hardware was corroded and the resin former for the coils was cracked.

After removing them from the aerial  I made notes of how many turns there was on the coil then I removed the wire coil.

This revealed the cracks in the resin formers.  

I decided to use some epoxy resin the fill the crack.

The wire that I had removed was 1.6mm aluminium and it just happened to be the same wire I use on my quad elements.

I wound new coils on the former with an extra turn added.

I then measured the resonant frequency using my analyser and reduced the length of the coil to bring to resonance at 7.1Mhz and repeated the process with the other trap.

Once the aerial was assembled and raised to 40ft at the feed point in an inverted V configuration adjustments were made to the wire length for best SWR.

Its been in the air for a few weeks now and has been performing well.

A big thank you to Nick for the write up and photos

all the best from the Club and Good DX



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