[TenTec] Strange FD RFI

[Kim Elmore]

You're right, Bob. As far as I know, this is a standard rotary AC 
alternator so doesn't do any inverting to get to the AC. As such, I 
expect (but didn't verify) it makes a more-or-less sine wave-ish 
output, but I have not looked at it. None of the other rigs seemed to 
suffer, which is what perplexes me. It's an 8-10 kW generator. When 
we looked at it with an analog meter, we didn't see much fluctuation, 
though we did see some.

Curiously, whenever another rig (with an external PS of unknown type) 
was used in the SSB position, I had no troubles. It was the FT1000D 
with an internal supply that caused me problems. My position also 
hosted the digital station. We shared the same antenna through an 
antenna switch so when I took a break, someone could man a PSK31 
position. I think that one was also an FT1000-type but had a Yaesu 
external PS that looked too small to be linear. It suffered no 
problems when the other '1000D with the internal supply was going full tilt.

The PS capacitors in my '930S are original and I have new ones with 
which to replace them. The ones that serve the 28.5 V side are each 
22000 uF (there are two). The power supply does not get hot, the 
regulation looks good, and there's no AC on the transmitter output. 
So, while these are indeed old they seem to be doing the job. 
However, I have new ones and will replace the old ones ASAP. I figure 
I'm running on luck right now.

I guess that I simply encountered something new on FD. Whatever it 
was, it was a unique combination of things that happened to make the 
linear supply in the 930S very unhappy. I also have an old KC Keyer 
that I have kept going and can't imagine CW without. It uses a linear 
wall-wart supply and it also showed signs of unhappiness, having 
locked up a few times. Once on the UPS, though, it never had a 
hiccup. Leave it to FD to find weak spots -- which is a good part of 
what the exercise is meant to do.

One good thing about the UPS was that when the generator had to shut 
down for refueling, I didn't! I was the only one there on a UPS, 
which was really pretty cool... "Wait a minute! Why is he still going?!"

Kim N5OP

At 09:53 PM 6/25/2012, you wrote:
>Also consider that the line impedance from the commercial source is likely
>much lower than the generator.  Generators don't like rapid load changes
>such as trying to follow the waveform of a SSB signal or CW signal.
>Likewise they attempt to correct accordingly.  There was a review of
>generators in a QST within the past 3 or 4 months as I recall.  Also many
>generators have a rather high level of distortion of the sine wave.  None of
>this would be shown on a DVM.
>
>In an effort to minimize weight in the radio and minimize size, the Vc
>filters are quite small.  After all they're likely OK for a clean power
>source but not so for a nasty one such as might be produced by a generator.
>Oh, another though on generators, were you using the inverter type or the
>old fashion rotor type?  The inverter types are not known for being clean,
>only efficient.
>
>As to the UPS, that's what they do, produce clean stable power.  Therefore,
>I don't view that there is any problem or issue with your radio.  Only the
>power from which it operates must be clean.
>
>73
>Bob, K4TAX
>
>
>----- Original Message -----
>From: "Al Gulseth" <wb5jnc at centurytel.net>
>To: <tentec at contesting.com>
>Cc: "Kim Elmore" <cw_de_n5op at sbcglobal.net>
>Sent: Monday, June 25, 2012 9:36 PM
>Subject: Re: [TenTec] Strange FD RFI
>
>
> > Kim,
> >
> > May be "apples and oranges" here, but have you ever looked at the AC
> > waveform
> > at the base of a typical cheap CFL on a scope? It's not pretty - the
> > switching PS in them puts a lot of garbage back into the AC line. I'm
> > wondering if something in your FD setup caused the '1000D switching PS
> > (AFAIK
> > it uses a switcher) to send some "hash" that might normally be suppressed
> > back down the AC feed to your rig's PS to upset it.
> >
> > 'Nuther thought - were the external PSes at the other positions linear or
> > switchers, or a combination? What brands?
> >
> > Or, it might be a plain ol' RF issue....
> >
> > 73, Al
> >
> >
> > On Mon June 25 2012 8:26:58 pm Kim Elmore wrote:
> >> I'll pop this out here to see if anyone has any good explanations for
> >> what I experienced.
> >> ....
> >> Has anyone ever heard of anything like this? Is there something
> >> unique about the FT1000D power supply or the rig itself that causes
> >> stuff like this?
> >>
> >> Kim N5OP
> >>
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