Opinions on this noise filter for my Yaesu 7900

clandr1

Adventurer
How do you have the 7900 wired? Do you have both the power and ground going all the way to the battery? That would be my first recommendation - if you splice into power wires, or use a power junction box, or ground it somewhere other than the battery's negative terminal, you may never be able to fully eliminate the whine in your speaker.
 

nat

Adventurer
I run a 100 amp deep cycle battery in the bed of my Tacoma, I wired my Yaesu to that. I get no interference unless my fridge is on, then I can hear the compressor on my radio. I already put ferrite chokes on the radio power at both ends as well as the fridge power.

I need an inline noise filter.

What are the opinions of the one I listed?
 

4x4junkie

Explorer
A large capacitor immediately where your 12V power goes into the fridge might fix that (I assume the noise is there even at the radio's minimum volume setting?). Maybe open up the fridge and see if you can solder a ~4700-6800µF @25V-rated cap at the backside of the DC power input jack.

It's also possible that noise filter you found is some sort of capacitor too, though unfortunately it doesn't appear to say what it is (if it's a choke it probably won't help much in your case, having already tried ferrites).
 

DaveInDenver

Middle Income Semi-Redneck
I'd do what 4x4junkie mentions, that's going to be the simplest thing with the best chance of working.

One question I have is what kind of fridge? Engels have a grounding screw for the case that helps knock down radiated compressor noise as well (doing this is basically mandatory when you run HF).

That filter you link might work but without seeing a circuit or inside it I'd just roll my own so I knew what it did. It's not difficult if you're at all handy with a soldering iron. Seriously, a 1-out-of-10 difficulty.

http://www.sanantoniohams.org/tips/whine.htm

In_Case.jpg
 
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mpinco

Expedition Leader
Found this with a quick google search. Feedback on the 10a version

http://www.amazon.com/product-revie...p-20&linkCode=sb1&camp=212353&creative=380553

It arrived with no continuity between the two hot leads. Took the unit apart.

Discovered one inductor and two capacitors, no printed circuit board, just an extremely poor hand soldering job. Not even sure they used rosin-core solder. They also used very thin wires.

I reworked the unit to get it to "work" as intented. It is a basic passive low pass filter circuit with the inductor in series with the supply and one capacitor to ground on each side of the inductor.

The inductor was small. 10 Amps? No way.



Ferrite chokes only slow high frequency noise, they do not shunt it. What you need is a low pass filter, comprised of a series inductor and parallel capacitor. Build your own. Follow DaveInDenver's link. Size appropriately.
 

DaveInDenver

Middle Income Semi-Redneck
I don't have one of their power line filters but in general Powerwerx is good to go, I'd trust their stuff if you wanted an off the shelf solution.

From the description there is nothing wrong with a very low pass filter (that's all the one I show is, about a 20Hz LP filter). But from the sound of it the commercial one might not be made well. The DIY using a quick link wound with #12 wire is probably good to 50A or 100A no problem. But more importantly it won't have much voltage drop across it, especially at the 10A your radio uses.
 

nat

Adventurer
Thanks for the replies! I had been looking at the Powerwerx filter too. My fridge is one from the TruckFridge site. I have a good soldering iron, maybe making one would be better?
 

gary in ohio

Explorer
that filter will not work. Your 7900 draws about 20+ amps on full power that filter was only 12 amps.

for your issue you need to determine if the noise is coming in on the antenna or the 12v lines. Unplug the antenna, does the noise go away? If so then its radiated noise and a power filter isnt going to help.
If it doesnt then try powering the radio from a second power source, (only need enough current for receive). does the noise go away. Is the fridge trulely 12 fridge or a 110v fridge on an inverter?
 

GlennA

Adventurer
We have some 30A noise filters at work that do a good job. They work best when attached at the load (radio) rather than the battery. It will be a few days before I am back in the office to get a manufacturer and part number. Now that the snow has melted, I am buried in work.
 

Arclight

SAR guy
I was able to replicate this problem with my TF51 and a Yaesu FT8900. It seemed to be worse when the fridge was in the back of the pickup with a long extension cord. The noise in question shows up on all of the VHF channels as a sort of warble/oscillating background static. Installing a snap-on ferrite bead helped quite a bit.

After I drive it some more, I may try a capacitor as well.

Arclight

Here's the information:

Antenex NS3035. 1-35 VDC 30A
 

DaveInDenver

Middle Income Semi-Redneck
Where did you put the ferrite? On the power or feedline? Also, do you remember or know the composition?
 

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