Re: 160 /80 / 60 mtr AM TX project
Thanks to the help and generosity of members of this forum I now have the tx operating on 160, 80 and 60 mtrs.
It's producing a nice clean 50 watts of carrier and easily runs up to 100 % modulation.
The following pictures show the modulation envelope / spectrum at 75 and 99% modulation.
Harmonics of the 1kHz modulation are approx 24dB down at full power and modulation.
I had to juggle with the plate / screen modulation ratios to get a nice trapezoid shape and adjust the screen phase compensation.
The modulation frequency response is 340Hz to 3.5kHz at -3dB.
The other spectrum shows PSU ripple on the carrier down at about -36dB, not as low as I would like but seems to be due to ripple on the PA HT line.
Still needs a few mechanical items fixing up, but basically ready for air testing - wish me luck
Regards Tim
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Building and tinkering for over 50 years, from 807's to digital amateur TV.
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