Icom R-20 , BC-149A Charger Runs Fairly Hot..Is this normal?

[N4UMJ]

Just wondering... I picked up a used R-20 with a BC-149A wall transformer and found the power supply to run fairly hot. Mine even had a slight electronics smell to it as I charged the R20 for the first time. The unloaded voltage out was measured at 6.2Vdc and it's rated at 1AMP so I am figuring there must be a big regulator on a heatsink inside. With the many vent holes I observed on the rear and sides I suppose should signal this is a hot running power supply.

Doing some calculating I am figuring 117 VAC @ 300mA input and 6Vdc @ 1000 mA output comes out to be 35.1 watts input and 6.2 watts output. So it appears the efficiency is not all that great and that would explain a lot. I did not see any notes in the manual about the X-fmr running hot and I do remember another ICOM 1 Hr quick charger I owned ran on the hot side(it was a LI-ION battery powered HT).

I'm having a fun time operating my new R20 and using all its features and seeing how it stacks up against my older R10!

Ed
N4UMJ

[bsdam]

Ed,

I've never noticed my wall transformer getting anything more than slightly warm. Maybe it is on its way out?

I love my R20 too, great radio, durable, and the battery seems to last forever. Awesome rig!

-B

Originally Posted by N4UMJ

Just wondering... I picked up a used R-20 with a BC-149A wall transformer and found the power supply to run fairly hot. Mine even had a slight electronics smell to it as I charged the R20 for the first time. The unloaded voltage out was measured at 6.2Vdc and it's rated at 1AMP so I am figuring there must be a big regulator on a heatsink inside. With the many vent holes I observed on the rear and sides I suppose should signal this is a hot running power supply.

Doing some calculating I am figuring 117 VAC @ 300mA input and 6Vdc @ 1000 mA output comes out to be 35.1 watts input and 6.2 watts output. So it appears the efficiency is not all that great and that would explain a lot. I did not see any notes in the manual about the X-fmr running hot and I do remember another ICOM 1 Hr quick charger I owned ran on the hot side(it was a LI-ION battery powered HT).

I'm having a fun time operating my new R20 and using all its features and seeing how it stacks up against my older R10!

Ed
N4UMJ

[hertzian]

Yes, it runs very hot on both the R20 and the new RX7. I had the exact same experience when I first got the R20 and was a bit surprised at how hot the BP-149 linear power supply became.

[hertzian]

Just ran a test on the BC-149A under a "kill-a-watt" meter:

Under no load / idling: 2 watts
Charging: 6 watts
Charge and operations: 7 watts

Since I only use the adapter for charging and not permanent use, I opted for a much smaller, lighter, and cooler switching supply. Both the R20 and RX7 use a RS "adaptaplug C". Here's a rundown on the #273-333 and 273-029 switchable voltage adapters (both similar only the 333 is rated 2A and the 029 rated at 1A. Results are similar:

(note: the 273-333 comes with 3 adaptaplugs, one of which is the "C" size.) The other adapter I had to get the plug separately)

No load / idling: 0 watts
Charging: 2 watts
Charge and operations: 3 watts

However, since they are switching, there is a bit of switching noise heard on BCB and HF AM. 30 mhz+ is not a problem. The antenna I used was basically a few feet from the adapter, so perhaps a remote antenna, with chokes on the feedline might reduce this.

For me, I travel with these switching supplies just for recharging, but the less efficient BC-149A linear supply is much quieter if you use these portables as fixed stations and listen to HF.