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

AdrianH · 18th Jan 2023, 9:36 pm

That is a thought, something like 16 or 17pF across the Tank coil (44uH) may tune out some of the 5.7 MHz, I could see how effective that work over the 5.25 to 6 MHz range, the 1.9MHz signal could not be treated that way when on 40, even if I include the 1.9 MHz notch on the driver anode I would still get around -30 from that.

I think I was expecting too much from such a simple circuit?

If it was going up to a tuned antenna I could expect a few less dB's for the spurii being out of the antennas band width, but it is not something I could measure and thinking along the lines of a long wire difficult to predict I guess.

Adrian

18th Jan 2023, 9:36 pm	#166
AdrianH Octode Join Date: Mar 2020 Location: Blackburn with Darwen, Lancashire, UK. Posts: 1,572	Re: Questions on 160/80 metre AM transmitters. That is a thought, something like 16 or 17pF across the Tank coil (44uH) may tune out some of the 5.7 MHz, I could see how effective that work over the 5.25 to 6 MHz range, the 1.9MHz signal could not be treated that way when on 40, even if I include the 1.9 MHz notch on the driver anode I would still get around -30 from that. I think I was expecting too much from such a simple circuit? If it was going up to a tuned antenna I could expect a few less dB's for the spurii being out of the antennas band width, but it is not something I could measure and thinking along the lines of a long wire difficult to predict I guess. Adrian __________________ Asking questions and learning, or trying to! Youtube EF91Valve