HAM radio issue

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Apr 4, 2006
I've been chasing a battery voltage problem. Turns out I have a brief ~180mA current draw between battery and aux fuse block: when I disconnect power to the fuse block, and then measure current between battery positive and power lead to the fuse block, I see a ~180mA current that quickly (within a second or two) drops down to ~2mA and the remains at that level. Never exceeds the 180mA, though.

Pulling fuses one at a time id'd the circuit to the HAM radio as the problem. Radio is a 2m Yaesu FT-1900R. When I pull the fuse, or unplug the harness at the radio, there's no current. Radio harness is fused only on the power side; haven't gotten around to rework the ground side of the battery.
Any idea what might be the cause? Despite my tech license, I haven't found it in my heart to learn the inner workings of my 2m radio. Not sure I want to install yet another switch, while that might cure the symptoms, I'd like to understand why this is occurring.
Last edited:
Many electronic devices will draw higher current when first connected to power that decreases over a period of seconds as the device charges all the internal caps etc and decides to go into standby. Obviously in standby the device will still draw some current since there is circuitry that is active waiting for you to press the 'soft on' button.

Seems to me based on your description that everything is working just fine.

The 'soft on' devices always draw some current versus a true on/off switch, but the advantage is that the high current is switched through electronic devices versus having it all have to flow through the true on/off switch.

Thanks for the explanation! The 2mA I'm not so worried about.
But this means I still get to hunt for what's slowly putting a drain on the battery, though.
This Red Top is going into its 8th year, but I'd like to find if/where there's a drain before I get a new battery.
Why not just pull the battery and have it tested?
Edit... new battery acquired after another no-start in the harsh winter conditions here in the garage in Baton Rouge...
Last edited:
Battery now is a X2 Power 27F from Batteries Plus as of mid-March...

...and the HAM radio -Yaesu FT-1900R- turned up dead as a doornail a few days ago.
Not sure what happened or when - the radio sees basically zero use.
I'll need to go through the wiring to see that everything is in order before I get another one, repair by Yaesu is almost not worth the cost.
...or I might just plop my Baofeng UV-5R in there.
direct wire your 2m (or ANY radio that transmits) to the battery with correct sized stranded copper wire that is fused on both the positive and negative wires. never use any of the native wiring/fuses etc.. Your negative to the battery negative post; your positive to the battery positive post. (both fused) Use at least 12ga copper stranded wire.

This will eliminate any spooky happenings with your other lights and devices. standard factory wiring is not designed for ham radios with high power requirements. (i doubt that you could transmit with 2mA)

Right now it's 10 gauge fused to battery ground, and 10 gauge to an aux fuse block right off the battery.
Cursory inspection hasn't revealed anything untoward with the wires running from the battery into the cab to the console.

I've decided to send the radio in to Yaesu for repair, see how that goes. It's not like I really need it at this point; we'll see.
Just for the record: got the radio back from Yaesu, defective surge suppressor, $0.56 in parts, $40 in labor, $30 shipping...
I guess now I really need to look at the wiring before I put the radio back in.
WIRE the radio DIRECTLY to the battery like fj60dave wrote above. That is what Yaesu shows in their manuals too...

Expensive lesson...

Not sure about the lesson part - yet. Negative was/is wired directly to the battery with an inline fuse; positive to the fuse block 8 inches from the battery. 10 gauge wire, 20A fuses each way, radio max power draw stated as 15A in the manual. Still no idea what has happened; if there were a lot of loads on that fuse block, I'd suspect shenanigans. But this truck has remained a mall crawler; the only thing that draws regularly is the Koso gauge; haven't used any of the rest (CB/LED lights/ARB/winch controls).

This radio has seen very little use since I rarely get around to it (I can hit the local net cleanly with the handheld), and so I don't have a good handle on what might have happened and when. I don't think I've ever transmitted at more than 10W. Purpose is more along the lines to gather a bit of experience, and decide whether I want a Ham setup in my trail truck.
Last edited:
Direct to the battery means direct to the battery, not through a fuse block/aux block etc..

Think of the battery as a big capacitor which is great at filtering spikes etc. If you connect your 'delicate' equipment to a distribution point, then it is now no longer connected directly to that capacitor (battery).

Anyhow, something spiked the front end of the radio OR it may just have been a bad/flaky part that failed. Without being there and inspecting all the connections and actual wiring that's about the limit of my remote diagnosing ability :)

Last edited:
Appreciate the input; I'll pull the wires and see...

Users who are viewing this thread

Top Bottom