[TowerTalk] HELP - Hy-Gain TH-3JRS

[Mike Fatchett W0MU]

At 8ft the antenna on 20 and 15 and probably 10 should look longer than 
it is.  You should have seen curves in the vicinity but I would not 
expect them to be properly lined up in those bands.  Did you refurbish 
or check the connections on the traps? It is odd that it sort of works 
on 15m but not the other bands.

I would take the driven traps apart and look for spiders or bugs or even 
old arc damage.  Make sure the coils are making good contact.

I had one of those antennas a long time ago.  I do not remember a beta 
match.  I am pretty sure I used a balun and direct connection to the 
driven element.  As Jim stated turns through 31 material is a current 
choke not a balun.

The director and reflector will have some influence on the SWR but not 
greatly.  The goal is to get the Driven working like dipole first.  If I 
recall the driven is isolated from the boom and the director and 
reflector are grounded to the boom.

W0MU Mike




On 5/17/2025 7:04 PM, Gary Mayfield wrote:
> Hello - We had a frustrating afternoon today trying to put up a Hy-Gain TH-3JRS at the QTH of Rich, KE0EPY.
>
> The antenna is previously owned, and we replaced the broken aluminum matching wire (beta match) with one made of copper. We have also added a balun made from type 31 ferrite material. Other than that, the antenna seems to be all original. A few days ago, we tested the antenna on top of an 8-foot fiberglass ladder, and it had three nice SWR dips right where you would expect for 20, 15 and 10 meters. Today before taking the antenna up the tower, we checked it all again, by pointing it lifting it a couple feet and pointing it straight up. Again, we saw 3 nice dips where they were expected.
>
> Once we mounted it on the tower the SWR went very high and only showed one small dip just below 15 meters at 20.8 MHz. Thinking the coax had been damaged we took a small jumper up in the lift and connected directly to the balun but got the same results. Then we bypassed the balun - same results. We removed the beta match and connected straight to the driven element and got the same results. With the beta match removed the two sides of the driven element are not shorted to each other or the boom.
>
> We have the lift for another day. Any ideas/thought/suggestions will be greatly appreciated!!
>
> Thanks, and 73,
> Joe - n0sd
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