[amsat-bb] Cushcraft dual band Beam - done

[Robert Bruninga]

Finally after 4 days of trying absolutely everything to get from 151 MHz
down to 145.8, including:  Extending elements with threaded nuts on all.
Extending driven element with 3/8" tips, extending boom as MFJ suggested and
extending tuning tube, I got closer to 145 MHz (from original 151 MHz)..
Got closer, but nothing below 2:1.

Finally made a new center rod for the matching section that is 1" longer
than the one provided.  THAT SOLVED IT PERFECTLY.  Got nice 1.1 SWR at 145.8
MHz as desired with everything restored to the original antenna.  And now
plenty of tuning range across all of two meters.

So there simply was not enough capacity in the tuning stub!

Bob, WB4APR

-----Original Message-----
From: Robert Bruninga <bruninga at usna.edu>
Sent: Wednesday, May 29, 2019 3:49 PM
To: AMSAT-BB <amsat-bb at amsat.org>
Cc: Robert Bruninga <bruninga at usna.edu>
Subject: Cushcraft dual band Beam

Any success with a cushcraft A27010S dual band beam?

Just got a new one and it tunes up perfectly to 1.1 SWR but only at 150.1
MHz.

Nothing we do with the matching network can lower the frequency to 145 MHz
where it is off-scale high SWR.

We now added 1/2" sleeves to the driven element and threaded on #10-32 nuts
on the end of all the wire elements to lower the resonance, but the best is
still only at 148.2 MHz.

Am going to try extended the two piece boom an inch and lastly will try to
extend the matching element.

Just wanted to see what others did to make this beam usable.

Bob, Wb4APR