How much hot should the finals get?

[Limeybastard]

While having the bottom cover of the 2970N4 removed and lowering the outrageous factory set dead key of 250W AM, I noticed the left side of the radio frame chasis gets hot very quickly, even after lowering the dead key. Infact the seperate amp unit itself barely gets lukewarm to the touch. Pic attached showing area that gets very warm. The silver chasis area where the wires are going across to amp. When cover is attached one doesnt feel or notice the heat as the silver frame chasis is covered by the amp cover.

 

[sp5it]

B754 can get hot in AM. That is why we go npc/rc/rwotb. No more heat, better performance.
Mike

 

[Limeybastard]

Yeah the frame where that item B754 is connected to gets hot. All the silver frame area.

What causes the heat? Is it related to the onboard amplifier?

 

[sp5it]

It is related with carrier lvl and modulation percentage. No worry, that transistor is not that expensive

 

[543_Dallas]

Warm is ok. I used to add extra heat sink to the back of the uniden grant for the am regulator. For a 148 and radio like yours I've mounted a heat sink to the top of the top cover and mounted the regulator to it, I've measured temps up to 170 degrees with continuous use and never had a failure on my personal rigs but check the datasheet for the device if you can find one.

You can also turn the variable power down a bit to take some of the load off. The red wire on the bottom (rwotb) will take a substantial load off of it because you're volting the final and then the am regulator only has to supply current to the driver. I don't care for this kind of mod but it works for the people that are into that kind of thing. I would run the radio at a reasonable output level and leave well enough alone.

 

[Limeybastard]

Im going to measure the temp of that aluminum? Panel later and post it. All it takes is a few 7 second dead keys on AM to warm up.
Thing is is the amp cover covers the outside of that panel so in essence prevents the heat to dissipate more, or maybe the amp cover removed is making it hotter? Lol

 

[Limeybastard]

Component B794 got it to about 129F and the area around the chasis frame near it was 98F. That was me yelling audio at bursts of 5-9 second intervals around 10 to 15 times.

 

[543_Dallas]

If that's as hot as it ever gets I wouldn't worry. My test was a little more brutal. The heat sink got to 170 fairly quickly and the temp stopped climbing. I left it transmitting mariachi music for 15 to 20 minutes and it seemed to have stabilized there. Different radio and different circumstances though.

PS
I stress test all my stuff like this with a dummy load. No hate mail or death threats are needed.

 

[fourstringburn]

That s

Component B794 got it to about 129F and the area around the chasis frame near it was 98F. That was me yelling audio at bursts of 5-9 second intervals around 10 to 15 times.

That doesn't sound like anything to worry about. As long as your fan is running you should be fine.

You have an amp with 4 large bipolar transistors. To create power it takes energy which in turn creates heat.

Your deadkey is good and your amperage draw looks way better now. A high SWR can have some affect too.

Do you recall the radio getting just as hot previously?

 

[543_Dallas]

That s

That doesn't sound like anything to worry about. As long as your fan is running you should be fine.

You have an amp with 4 large bipolar transistors. To create power it takes energy which in turn creates heat.

Your deadkey is good and your amperage draw looks way better now. A high SWR can have some affect too.

Do you recall the radio getting just as hot previously?

The am regulator is for the finals in the radio that drive the built in amp.

 

[Limeybastard]

That s

That doesn't sound like anything to worry about. As long as your fan is running you should be fine.

You have an amp with 4 large bipolar transistors. To create power it takes energy which in turn creates heat.

Your deadkey is good and your amperage draw looks way better now. A high SWR can have some affect too.

Do you recall the radio getting just as hot previously?

Hi, its the area not on the amp section. Its the silver frame where component b754 is mounted to . That whole aluminum area, which doesnt have a heatsink.

I didnt have the cover off to know if it got hot before the changes were made, problem is it doesn't feel hot when the amp side of the cover is on, since it covers the aluminum area which gets hot per my picture.

 

[fourstringburn]

That appears to be like a heat asorbing heat shield cover.

543Dallas agrees that it seems ok to run. Your outer heatsinks will do their job along with the fan.

One comforting thought is if you bought that radio new, you haven't done any mods that would void the warranty and Ranger has a 2 year warranty.

If you really need the technical lowdown and the best one to ask with your concerns, you can contact Ranger communications and speak with Chip directly. He's a nice guy and very knowledgeable with RCI radio's.

You can get his contact info from

http://www.rangerusa.com/contact_us.html

 

[JoeDirt]

Dont worry about it, its normal. I have blisters from my Galaxys. They have been abused for over 10 years now no failures.

If you're worried about it you can "volt" the final. That will take the load off that transistor.

 

[338_MtRushmore]

Just run it. There is no way to cram a radio and good size amp into a little box without stuff getting warm. Just be respectful to it and run it into a decent antenna.

 

[nomadradio]

Bias set too high on the radio finals?

The IRF520 is power hungry, and tends to make that part run hot even when bias is set correctly. 10 or 20 mA per final (on the radio pc board) is safer.

73