PGXL Fan temperature

John K3MA

I have noticed that when I leave the PGXL fan running at the "C" setting and am not using the station the PGXL temperature stays in the low 50C range. Even if sitting unused for half an hour or more. Again this is with the PGXl not being used and no transmitting from the exciter.

If I switch it to the "S" or "B" setting it quickly brings the temperature down to the mid/high 30s where it stays until I decide to transmit using the PGXL again.

Does anyone else have this condition? It does not strike me as normal but maybe it has a valid explanation.

David Decoons, wo2x

Inn C (contest), the fans ramp up a little quicker and remain at very low level in RX.

In standard the bias shuts off after two minutes of no TX. 4 amps at 50 volts is 200 watts dissipation.

In contest mode the bias remains on allowing for quicker RX to TX switching on initial TX.

in broadcast the bias remains on but fan speed is full speed so it keeps amp cool.

Dave wo2x

John K3MA

Dave, thanks for the more detailed explanation of the operation in each mode. So I guess the answer to my question is that every other PGXL with the current firmware version will exhibit this same higher temperature when left in contest mode (C) and it is because the bias is left on all the time but the fan is not moving enough air at that temperature to cool it lower than the low 50C range.

David Decoons, wo2x

Correct. The bias on all the time results in heat dissipation. As it warms up, the fans will increase to keep it around 50c.

If you are using it in a casual manner and not contesting, just put it in standard. The time to turn on the bias on initial transmission is very quick.

Remember to set TX Delay on the radio to 30 ms.

Dave wo2x

Mike-VA3MW

I use Contest mode during the cold months here to keep my remote radios warm. Yes, I have to leave the amp in operate mode, but it has worked well for a number of winters so far.

John K3MA

Thanks Dave. I had thought the standard TX Delay should be 20 ms. Is that something different requiring your recommendation of 30 ms? Not an issue as I won't notice the difference but I was just wondering if there was a technical reason of just your preference.

Mike, nice idea to utilize the heat in the remote shack.

David Decoons, wo2x

With the PG XL, TG. l and AG it is recommended for TX Delay to be 30 ms and CW Delay to be minimum of 30 ms. This is withPH 3.8.4, TG 1.1.20, and AG 3.1.5. This gives enough time for everything to switch and be ready to TX. Any shorter and you risk having Interlock errors.

Dave wo2x