[RFI] Recommend a Small Low-RFI Inverter?

Jim Brown jim at audiosystemsgroup.com
Sat Sep 30 19:53:52 EDT 2017


On 9/30/2017 11:46 AM, Kenneth G. Gordon wrote:
> Samlex, pure-sine-wave inverter. Get the model(s) which are specified as low or no RFI. I bought a 300 watt version (don't have the model number handy) and am very pleased with it.

Hi Ken,

I do NOT share your experience with these inverters. I bought Samlex's 
smallest PST-series unit to power the logging computer for our 7QP 
county mobile operation. I was able to make it quiet enough, but it 
needed a LOT of ferrite cores  to do it. Another member of our team 
bought one of the bigger PST units, (maybe the 300W version) and we were 
not able to make it quiet enough. The thing that makes it hard is that 
the antennas are VERY close to the inverter, and any trash on the power 
wiring roars into the antenna.

Slide # 213 in the link below

http://k9yc.com/KillingRXNoiseVisalia.pdf

shows what I had to do to make the PST-120-12 quiet enough to use in the 
mobile with a hamstick on the back. The top two chokes (the largest 
ones) were not needed for 20M/40M in the mobile, but were needed to keep 
the noise out of the 160M vertical about 30 ft from my operating desk at 
home. The smaller chokes with 4-5 turns are for 40 and 20, the 
single-turn clamp-ons are for 2M.

Noise is, of course, a matter of degree. We were operating from very 
quiet places in the middle of nowhere, where the local noise is S1. If 
you're using the inverter in an urban environment (or in a noisy 
vehicle) where the noise level is S9+, you're less likely to hear the 
noise from the inverter.

73, Jim K9YC




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