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Heatsink temperature of IRF510s #ubitx

Martin Potter
 

Just waiting for my uBitX V5 to arrive and wondering how hot the IRF510s in the PA might get under normal operating (transmitting) conditions. I am thinking of putting an LM35 temperature sensor on one of the heat sinks just to keep an eye on the temperature. Has anyone done this with V4 or V3? Is it worthwhile?

As I recall, the LM35 gives a linear output voltage directly proportional to temperature, 0-50 C. I used one on the PA of a beacon transmitter I built many years ago and was very happy with the results. (There was never a temperature problem, but at least I knew what it was.)

Thanks for any info.
... Martin VE3OAT
 

Perhaps , nothing is needed, being a QRP.
Many people might prefer to reduce power out to 1 or 5 watts and use external Liner, instead.

regards
sarma
vu3zmv


On Fri, Mar 1, 2019 at 7:18 AM Martin Potter <ve3oat@...> wrote:
Just waiting for my uBitX V5 to arrive and wondering how hot the IRF510s in the PA might get under normal operating (transmitting) conditions.? I am thinking of putting an LM35 temperature sensor on one of the heat sinks just to keep an eye on the temperature.? Has anyone done this with V4 or V3?? Is it worthwhile?

As I recall, the LM35 gives a linear output voltage directly proportional to temperature, 0-50 C.? I used one on the PA of a beacon transmitter I built many years ago and was very happy with the results.? (There was never a temperature problem, but at least I knew what it was.)

Thanks for any info.
... Martin? ?VE3OAT
Dave Dixon
 

Hello all,
?????????????? I read al the mail each day with interest.Ive been using my version 3 as my main station for 12 months or more with no increased heat from the irf 510s the votage regulater gets very hot so fitted heat sink to it? but the irf 510s just get warm,im 100% cw.and normally try to have a good natter,my ubitx is housed in an excellway ef 01 case an ideal case as its light to take portable weighs very little..I fitted an external cw variable filter which works very well,im over whelmed by the way this radio works and sold all my commercial equipment,I am,all homebrewed now. and enjoying the hobby very much.DAVE G0AYD CW OPS 2149? FISTS 15892...GQRP 3309 RSARS 4209.

On Fri, 1 Mar 2019 at 04:03, MVS Sarma <mvssarma@...> wrote:
Perhaps , nothing is needed, being a QRP.
Many people might prefer to reduce power out to 1 or 5 watts and use external Liner, instead.

regards
sarma
vu3zmv


On Fri, Mar 1, 2019 at 7:18 AM Martin Potter <ve3oat@...> wrote:
Just waiting for my uBitX V5 to arrive and wondering how hot the IRF510s in the PA might get under normal operating (transmitting) conditions.? I am thinking of putting an LM35 temperature sensor on one of the heat sinks just to keep an eye on the temperature.? Has anyone done this with V4 or V3?? Is it worthwhile?

As I recall, the LM35 gives a linear output voltage directly proportional to temperature, 0-50 C.? I used one on the PA of a beacon transmitter I built many years ago and was very happy with the results.? (There was never a temperature problem, but at least I knew what it was.)

Thanks for any info.
... Martin? ?VE3OAT
 

I have had the output transistors get hot. when tuning on 80. and have put in oversized heatsinks and a small ducted fan on each of them. They can get hot doing digital.

That said after one tuning on 80 that took longer than expected there was significant heating, too hot to touch. That unit had stock heatsinks and no fan at the time, but in the end no ill effects.

I am definitely olds cool when it comes to running transistors cool and run the fans 100 percent of the time. Have thought about using a sensor but in the end simplicity won out.
 

On my bench I have not blown any IRFs due to temperature/overheating.

I have absent mindedly left the uBitx on TX and noticed the power drops when
finals get too hot.

All depends on your use if you need to cool it or put bigs sink.

At 01-03-19, you wrote:
I have had the output transistors get hot. when tuning on 80. and have put in oversized heatsinks and a small ducted fan on each of them. They can get hot doing digital.

That said after one tuning on 80 that took longer than expected there was significant heating, too hot to touch. That unit had stock heatsinks and no fan at the time, but in the end no ill effects.

I am definitely olds cool when it comes to running transistors cool and run the fans 100 percent of the time. Have thought about using a sensor but in the end simplicity won out.
Martin Potter
 

Thanks to everyone for your replies and comments. It seems there is not really much problem with temperature, except perhaps sometimes on 80 m under heavy CW operation or when repeatedly tuning an antenna.

At present I think I will install an LM35 sensor, "because I can". There will be an analog meter in any case to monitor the battery boltage and keep an eye onthe PA current, and for the AGC if I ever get around to installing that. So temperature is just an extra position on the meter switch HI Who knows, it might prove really useful, or merely interesting. Lots of time to decide before the uBitX arrives. Thanks again for your thoughts and ideas.

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