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@usna.edu Sent: Wednesday, May 29, 2019 3:49 PM To: AMSAT-BB amsat-bb@amsat.org Cc: Robert Bruninga bruninga@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