On 30 Sep 2017 at 16:53, Jim Brown wrote:
> 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.
I am amazed! In our case, we could have used the case of our Samlex for an
noise output was so low. I wonder if the age of our respective units has
anything to do with
> 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.
We also used my PST-300-12 for the past two Field Days, and none of us have
noticed whether or not it was on, but our antennas are a LONG ways from where
being used too.
> Slide # 213 in the link below
> 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.
As I said, I am amazed. Truly. Our experiences with the Samlex are far
different from yours.
I wonder why?
> 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.
Our noise level at our FD sites was below S-1.
I have personally only used it in a mobile to power some DF equipment. There
change in the noise level as measured by the NM-20B whether running on the
Samlex or on
When I would take my noise measurements, the car would be turned off, so that
was not a
I wonder what the difference is?
I'll contact the fellow here who made some exacting measurements and get his
post here as soon as I can. The figure -76 dB is yeasting around in my memory,
but I don't
remember, at all, to what that applies.
As I said, twice, I am amazed at your results. Those are entirely strange in my
Have you contacted Samlex about this? As I mentioned previously, they are
designed to be used in ambulances, so they HAVE to be RFI-quiet.
It sounds to me as though further research is in order here.
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