PGXL operation in AM mode

K1VL

I'm interested in hearing any experiences PGXL users have on running the amplifier in AM mode. I'd like to know what power level you typically operate the amp at and any tips on general operation such as fan modes, drive levels and so on. In theory the full legal limit in the US is 375 watts carrier at 100% modulation, that should roughly equal 1500 watts PEP. I am planning to take part in the 2022 AM Rally (AMRally dot com) this coming weekend with my Flex 6500/PGXL combination and I would love to hear your experiences in running the PGXL on AM.

Mack W4AX

I use my 6600/PGXL/TGXL/AG often on 3885 Kc AM with no issues. I set the carrier power to about 200 watts and I suppose I could go higher but it really doesn't make a difference. I typically transmit for 2-5 minutes every 10 minutes or so. I have never had an issue with the PGXL overheating. I do monitor the temperature and run the fans in Contest mode. For me this is not a distraction since the aforementioned equipment is located in a separate conditioned room at the antenna entry panel away from the shack.

I recommend two things: 1. Monitor the PGXL temperatures and keep them below the limits in the manual. The PGXL does have temperature protection circuits but I wouldn't let it get that high. Move the PGXL away from your microphone. AM is continuous carrier like RTTY or FT-8 so the fans will be louder than normal. It's just physics.

Let me know if I can answer any other questions for you and I hope to work you on AM one morning.

Vy 73,

Mack

W4AX

K1VL

Thanks Mack! I tested out the PGXL on AM with QSO's on both 80 and 40 meters this week with great results. It performed flawlessly at around 200 watts carrier which was just about 1500 watts PEP with positive modulation peaks extending to 150% and negative peaks around 96% per my LP-700 station monitor. I kept an eye on the PA temperature and it floated up to around 60 degrees during longer fully modulated transmissions with the fans in contest mode. On the dummy load I could easily run higher a higher carrier with 2000 watts PEP peaks no sweat. So a great success from my perspective. I am now working the sweet spot on the 6500 for best all around sound and optimal positive peak modulation. Various test combinations of RF Power and AM Carrier sliders yield best overall modulation with the AM Carrier control is set in the 75 to 80 range. This lowers the transceiver's maximum barefoot carrier power output a bit but creates enough RF amp headroom for excellent positive peaks. The PGXL handles the rest!

Carmine W1EQX

W2ENY

Where is my answer from months ago regarding phase rotation/inversion when using a usb pc mic?
Tnx W2ENY using Flex 6500 and 6300(s)

Kevin_1969

I was going too try a 300 watt carrier, when I get mine tomorrow, but maybe I should start out with 200 since 10 minute buzzards are the norm where we operate. Will see what happens. Thanks for the info guys!