Inverter HF interference ?

Submitted: Wednesday, Jan 26, 2005 at 08:46
ThreadID: 19785 Views:2218 Replies:3 FollowUps:2
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I know the theory but...... can anyone tell me if the current generation of non sine wave inverters (eg, the ones that run lappies etc) cause much interference to a HF radio ?
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Reply By: davidta - Wednesday, Jan 26, 2005 at 09:23

Wednesday, Jan 26, 2005 at 09:23

I had an 800W modified square wave 12 to 240 V inverter in the Patrol and it caused significant interferance to my HF.
I changed it to another brand & still had the problem.
I changed it for a 1000W Pure Sine Wave - NO interference.
This was with 2 different brand HF's as well.
AnswerID: 94955

Reply By: Mike Harding - Wednesday, Jan 26, 2005 at 09:33

Wednesday, Jan 26, 2005 at 09:33
They might - so might the sine wave ones.

Because RF/electrical "noise" and it's propagation is such a complex area it's impossible to be more definitive. My assumption would be that square/tri wave inverters would be more likely to cause problems but even that would depend upon a myriad of variables.

A friend of mine happily runs his Amateur HF set off his inverter and is happy with it but I have heard him make contacts where the chap at the other end said he could hear inverter whine. I prefer to run mine from a battery.

At the very least any electrical/electronic equipment which causes rapid current change and is operating in the immediate vicinity of a radio will, most likely, degrade the Rx ability of the radio.

Take a portable radio to the place you will be buying the inverter from and tune it to a quiet section of the MW band then switch the inverter on and ensure it is powering a load and see what happens with the radio? Not a definitive test but cheaper than a broad band spectrum analyser :)

Mike Harding
AnswerID: 94956

Follow Up By: hl - Wednesday, Jan 26, 2005 at 10:04

Wednesday, Jan 26, 2005 at 10:04
Most likely it will be audible, but the switchmode supply for the laptop can do it too, so can the laptop...... and so on.
Jaycar sell some clamp-on ferrite surpressors which can be useful.

FollowupID: 353813

Reply By: Member - Raymond - Wednesday, Jan 26, 2005 at 10:57

Wednesday, Jan 26, 2005 at 10:57
Hi Footloose
I have an inverter in the Ute which runs the laptop (moving map) and the battery recharging for phone etc, it is a 300w modified sinewave from Radio Parts and it causes no interferance to the HF radio (Barrett). The Danfoss compressor on the fridge is the biggest noise problem for the HF, if anyone knows how to fix it, please post.
AnswerID: 94969

Follow Up By: hl - Wednesday, Jan 26, 2005 at 14:42

Wednesday, Jan 26, 2005 at 14:42
WAECO have known about this problem for years, but have failed to fix it even though it would cost very little to do in production. I have a fix worked out by a fellow radio amateur. It is quite involved and requires a lot of dismantling, but will reduce it greatly. You can email me if you want to go ahead.
(For a a bit of light entertainment, read the drivel on the WAECO website that is their official answer to the problem)
I know of a few yachties too that have give them the flick, once they realized where the interference came from.

FollowupID: 353837

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