Hello Mike You have a good question below. I have some numbers for you.
The PA will run full power to 100 C at which point it will cut itself to 25% of indicated drive level. You can set the temp at which the fans go to high, Adding some extra cooling will help also, as the fan slow down when not transmitting, normally we listen more than we transmit. I did a test. I turned off both mic gain (to zero) and power out to zero as well. Then I keyed the MOX and watched the temp rise. With fan running, the temp went up to 49.1c (120.38f). That is when I shut the TX down. Remember that is with FAN RUNNING and only resting current (no power out). That means that during times of CW, I am not only generating heat during the dits and dashes, but also in between because of resting current. Removing 28 watts final and perhaps 14 watts of driver heat will help. I have been reducing my output to 80%, but it would be nice to feel good about running full 100watts during a contest. Many contest have the rules at 150 watts (not 100w) so can be at a disadvantage even at 100%. Remember in a (pile up) as little as 1db makes a big difference. Most RF men who do not work pile ups, forget that. If you have three people in the same pile up, the guy with only 1db better signal is the one who gets answered first. In contest or DX that is a BIG deal. Those are the numbers. Hope this helps. Let me know. 73, Bruce, W8HW I repair two way radios including ham radios ----- Original Message ----- From: "Mike" <mi...@m0aws.co.uk> To: "W8HW" <w...@att.net> Sent: Monday, September 05, 2011 8:40 AM Subject: Re: [Flexradio] 58 Degrees and rising .... > Hi Bruce, > > Thanks for the reply. > So what is a safe temperature for the finals to get to??? > Is 60c too hot?? Should I configure PSDR to bring the fans on earlier or > perhaps have the fans running all the time? > > The PSU shows an 8A draw at 5w, a lot of current for such a small O/P!! > > Mike. > > On 05/09/11 13:00, W8HW wrote: >> Yes it can be normal. The bias of the finals (and drivers) are such that >> even if you were to MUTE all audio and key the transmitter lots of heat >> is generated. This happens even if you see no power out, Try this some >> time, turn your audio all the way down and key your transmitter. Note >> that the current from your 12v power supply jumps up. If you were to >> leave the transmitter keyed, the temp of the final rises and your fans >> will start to run. Because bias (causing resting final current) results >> in no power out thus it is ALL heat. >> >> 73, Bruce, W8HW >> I repair two way radios including ham radios >> >> >> >> ----- Original Message ----- From: "Mike" <mi...@m0aws.co.uk> >> To: <flexradio@flex-radio.biz> >> Sent: Monday, September 05, 2011 5:49 AM >> Subject: [Flexradio] 58 Degrees and rising .... >> >> >>> Hi All, >>> >>> I have a quick question for you all .... >>> I ran an over night WSPR session on the 40m band last night with just 5w >>> of O/P from my F3K. >>> >>> I was somewhat surprised to see the temperature of the PA being reported >>> to be at 58 degrees C and at times over 60 degrees C. >>> >>> Is this normal when running at such low power levels? >>> The fans were set to come on at 40 degrees C thus they were on a heck of >>> a lot! >>> >>> What is the max working temperature of the PA in the F3K? >>> or put another way, at what temperature do I need to shut things off to >>> stop them going pop!! >>> >>> The F3K was running at 13.8v from my Diamond GSV3000 PSU as always. >>> >>> I had WSPR set to 20% TX and 80% RX. >>> >>> Mike. >>> M0AWS >>> http://www.m0aws.co.uk >>> >>> >>> >>> _______________________________________________ >>> FlexRadio Systems Mailing List >>> FlexRadio@flex-radio.biz >>> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >>> Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >>> Knowledge Base: http://kc.flexradio.com/ Homepage: >>> http://www.flexradio.com/ _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
