UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Questions on 160/80 metre AM transmitters.

Cruisin Marine · 24th Dec 2022, 10:12 pm

Re: post #81, I guess the modification by

"Pat, G3IKR suggested a modification to me which can slightly increase output on
80m. The L3/C9 combination is only roughly tuned and is not adjustable as it
stands. Pat suggested replacing C9 with a 60pF trimmer which is adjusted for
maximum output on 80m. I peaked mine in the phone section and increased RF
output by about 1.5 watts."

would put in to doubt that L3/C9 is a series acceptor tuned cct. to eradicate 1.9 MHz signal when switched to 80 Metre? or maybe not?
Perhaps peaking the rejection/leakage from 1.9 MHz increases the o/p on 80metres as well as doing its own job too by cleaning up the drive energy to be just concentrated on 80m.

24th Dec 2022, 10:12 pm	#85
Cruisin Marine Heptode Join Date: Jul 2018 Location: Worthing, West Sussex, UK. Posts: 992	Re: Quick question on the CODAR AT5, if anyone has one to hand. Re: post #81, I guess the modification by "Pat, G3IKR suggested a modification to me which can slightly increase output on 80m. The L3/C9 combination is only roughly tuned and is not adjustable as it stands. Pat suggested replacing C9 with a 60pF trimmer which is adjusted for maximum output on 80m. I peaked mine in the phone section and increased RF output by about 1.5 watts." would put in to doubt that L3/C9 is a series acceptor tuned cct. to eradicate 1.9 MHz signal when switched to 80 Metre? or maybe not? Perhaps peaking the rejection/leakage from 1.9 MHz increases the o/p on 80metres as well as doing its own job too by cleaning up the drive energy to be just concentrated on 80m. __________________ "Behind every crowd, there's a silver Moonshine" Last edited by Cruisin Marine; 24th Dec 2022 at 10:27 pm.