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

Cruisin Marine · 20th Dec 2022, 11:11 pm

In fact I can see no frequency doubling, just the notching of 1.9 MHz from driving the PA valve. I know the circuit must work or the AT5 would not have received good reviews, as I am trying to build my own variant of it and the many copies out there I would like to understand the circuit better in my own mind.

I personally would have two switched parallel resonant ccts desiged for 1.9 and 3.5 MHz resonant ccts in the anode of the driver valve L2 which I notice is a currently 2.5 mH wideband choke.
Maybe one coil and a capactor switched in or out could achieve this aim, or a tapped and switched coil if not.

20th Dec 2022, 11:11 pm	#31
Cruisin Marine Octode Join Date: Jul 2018 Location: Worthing, West Sussex, UK. Posts: 1,007	Re: Quick question on the CODAR AT5, if anyone has one to hand. In fact I can see no frequency doubling, just the notching of 1.9 MHz from driving the PA valve. I know the circuit must work or the AT5 would not have received good reviews, as I am trying to build my own variant of it and the many copies out there I would like to understand the circuit better in my own mind. I personally would have two switched parallel resonant ccts desiged for 1.9 and 3.5 MHz resonant ccts in the anode of the driver valve L2 which I notice is a currently 2.5 mH wideband choke. Maybe one coil and a capactor switched in or out could achieve this aim, or a tapped and switched coil if not. __________________ "Behind every crowd, there's a silver Moonshine"