View Full Version : Where to connect HF radio power?

04-25-2011, 04:17 PM
What's the recommended connection point in a motorhome for 12 VDC to power an HF rig that draws about 20 amps during TX?

Since I won't be operating while in motion, my first thought is a direct connection to the house batteries or the battery disconnect switch. But then I begin to wonder if the connection should be at the converter 12 VDC house output, so as not to upset the multi-stage charging function, which depends on battery voltage.

Will a direct connect to the battery confuse the converter's charging function?

Would a connection to the converter be preferred?

What are you using?

04-25-2011, 07:16 PM
Welcome to ORR.net! :welcome:

I have a 50 watt vhf/uhf rig in my 5th wheel running direct from house batteries. Doesn't seem to bother the converter at all. And it's very quiet. I was "certain" the converter would inject some sort of noise/hash/garbage into the radio but it doesn't.

I suspect you'd get the same results. When parked I use either a separate deep cycle battery or a Astron 35M power supply for the HF rig, on those occasions when I decide to take it along.

The motorhome crowd on ORR.net is a friendly and helpful bunch. You'll get more assistance when they check in and find your post.

Again, welcome aboard ORR.net!

04-25-2011, 09:01 PM
I agree. I have my 857d running to the house battery via powerpole connections. I can just plug it in when i want to play on HF and it is free of any component noises. I also have a solar panel on the roof that trickles the house battery and all run smooth. I dont keep it permanently installed because i also like to run the radio from my toad.

04-26-2011, 07:56 AM
My IC V8000 is plugged into the accessory outlet and can run full power with no problems. The outlet is fused at 20 amps, so plenty of power for the rig. My HF rig, IC 736, is only plugged in when I'm on shore power since it's ac outlet is not connected to the inverter. I don't do much boondocking, so it's never been an issue for me. My chassis batteries are connected to the coach batteries when I am parked, so the V8 doesn't run my chassis batteries down when I do a lot of long winded rag chewing.

07 Dip

04-26-2011, 10:25 AM
A lot depends on the motor home.. Recommended point is ALWAYS the batteries direct, House would be my choice but either works. HOWEVER, in some cases there are easier connection points.

On my coach the small room where I wanted to put the radio was right beind the main fuse block.. In fact the wall it is mounted in is shared.

I added another fuse (There were many blanks in the panel) and viola, hooked up.. The wires from there to the battery are dang near staarter cable grade.

04-29-2011, 02:16 PM
You didn't say what exactly you have, so I will tell you what I did.

You can apply it to your circumstances.

My coach has 120v outlets supplied by 4 8D batteries and an inverter/charger.

It is configured so that shore current or generator run through the inverter/charger or battery, whichever power source is called upon/required.

I pondered your question and initially thought of hooking directly to the battery.
The downside of that was that the batteries were not conveniently close to the radio installation point, so I added a 35 amp power supply to an 120v outlet found in the radio install location.

Until I tried the my setup I had no idea if it would be "quiet or noisy" with some luck I find it very quiet and am happy with the results. :bounce:

What ever you do be sure to fuse both leads . :poke:


04-29-2011, 02:24 PM
Forgot to mention, you didn't say what the specified operating voltage for your rig is.

In my case with an Icom-7000 it is 13.8 +- 15% and they mean it.

If you go lower than that you will be very disappointed in the performance and will most certainly have problems. Mine never goes below 13.8V.


04-30-2011, 01:35 PM
I would go with the batteries or disconnect switch before I'd connect to the converter.

Now, what I did: IN my coach the converter is in the back, Driver's side, as far from the entry steps as you can get... The bateries are under the steps, the power runs up under the "Hood" (This is front engine gasser) and then back to both a fuse block about 25 feet back and the converter 35 feet back give or take a foot.

This is wire capable of hauling 80 amps with minimum loss.

I "Tapped" a spare slot on the fuse block, being as the radio is ... About 3-4 feet outside-wall wards of the fuse block, zero feet in front or back of it.

Almost got away without extending the radio's suppied power cord (Added about a foot)

05-02-2011, 05:17 PM
Thanks for the suggestions. I think I'll see what wire gauge I have between batteries and converter, then make a decision based on ease of wiring.

I can always change the connection point if I have a problem.

See you on the air!


05-03-2011, 08:50 PM
Just for the sake of telling this story.
Our MH is some what vintage, after having a set of new house batteries go bad and get replaced I started to wonder about the power quality of the charging system.
Went to the shop and found my little Tectronix portable scope and connected to the battery, found about 6 volt's of AC ripple on the line from the inverter, back to the "Junk Box" (aka "the shop") dug around till I found a 50 amp full wave bridge and fell across a couple of 1000 Mfd 50 VDC electrolitics, did a little creative re-wireing and now have a very clean 14.2 going to the batteries.
BTW, the inverter is an OEM "MagnaTeck 6345".

05-10-2011, 06:53 PM
I run a Kenwood 480HX so I ran number 6 wire to the house batteries and added a 50 amp circuit breaker there ( brown item at bottom center of 1st pic). No noise or issues so far with the converter.

http://www.openroadsradio.net/attachments/photobucket/img_8364_0_ce0e29fd8dabc8549f349324469e8a0c.jpghtt p://www.openroadsradio.net/attachments/photobucket/img_8364_1_48b1c91ad1827a9e8b29434226d0c636.jpghtt p://www.openroadsradio.net/attachments/photobucket/img_8364_2_b5f52b20a85b9bea01e45d2c5d27e80a.jpg

05-14-2011, 04:30 PM
I run an FT857D direct to the Rv batteries. Power is clean and does not bother the Progressive Dynamics converter.