[RFI] Intermittent noise, all bands, 2 antennas and 2 sets of finals lost

Roger (K8RI) k8ri at rogerhalstead.com
Tue Oct 27 00:54:25 EDT 2015

I'll try a more appropriate title this time

It's easy to see the relationship when looking back, but remember these 
problems were spread out well over a year.  I'm going from an old memory 
recalling events, some of which  more or less seemed trivial at the 
time, so some of this may seem disconnected.

Around the first of the summer I noticed a noise that would come and go 
at irregular intervals.  It was kinda like precip static that starts out 
as a series of pops, that get closer together until they became a low 
frequency buzz, which quickly goes up in frequency to either end with a 
pop, or just fade out.   Similar, but different is the only way I could 
describe it and it didn't always sound the same. Something it just 
sounded like something was arcing.  It wasn't really strong either.  Two 
different problems, or one with a personality disorder?

To begin it didn't happen all that often, but as time moved on it 
happened more often  At first it bothered so seldom that I really didn't 
have any concerns. As time went on, it became much stronger, more often, 
and downright annoying

I had the matching network fail in the big Diamond 144/440 duo band and 
lost the VHF finals in the Yaesu 897D.  I replaced those finals, or 
rather sent the rig into Yaesu who had it back to me in short order.  I 
replaced the Antenna with a new one of the same make and model and 
hooked up my TMV-7A. Looking good.

BUT, about a year later (give or take) I was talking with one of the 
locals on his way home.  He remarked that my signal started getting 
noisy as if I were a mobile running out of the system.  Hmmm, Heat sink 
was hot, so I immediately shut down.   SWR was sky high!  Yup! The 
matching network in the antenna was shot.  The general consensus was 
that I had a grounding problem as in earth grounding,  yet the grounds, 
including the green wire "to the 200A service panel" appeared to be good 
with all the checking I did.

Over a year ago, my CAT 5 Gigabit network took a strong jolt from a 
close lightening strike.  There were three 130' CAT-5 runs from from the 
smart switch and router in the basement to the shop. It wiped out both 
the router and switch as well as the motherboard in that computer.   It 
also welded the run to the socket in the UPS for the main computer in 
the shop (the one that lost the motherboard). I went wireless, replaced 
that computer with my back up unit and replaced that storage  (four,  4 
TB drives) with a 16 TB server in the shack in the house.  (Easy to shut 
down and disconnect.)  No more CAT 5 to electrocute my computers.

NOTE: it was several months after the lightening strike that I lost the 
first antenna.  The second antenna failure was nearly a year after that

BTW the computer that lost the motherboard was the biggest and fastest 
computer I had.   The computers have 850W to 1 KW power supplies.  Each 
runs of its own 1.5 KVA UPS.

On what I thought was a completely different, computer problem; when 
viewing AVI, or streaming video, the computers would hang or do a good 
imitation of "Max Headroom".  Strange...The frequency and severity of 
this also increased as summer progressed.  THAT had me thinking that 
they must/might be related  and the one computer that was the worst 
offender was the one in the shop, but they all had the problem to a 
lesser extent and the one in the shop was now wireless. The one in the 
shop was powered off the original UPS.as were the power supplies for the 
station in the shop.  Remember too that the antenna system ground ties 
all of the grounds together.

I shut down all the electronics in the shop, switched every thing 
connected to "that" UPS to the one for the spare computer. Amazing, "Max 
Headroom" was now silent and the noise on the rigs was gone.  I don't 
know how much of these happenings were related to the lightening strike 
and how many were related to the UPS.  The question comes up as to why 
it didn't/doesn't trip the GFI.  "I think"  The output of the UPS is 
isolated from the line.  That GFI has tripped a couple of times, but 
only a couple of times.  It takes only a tiny bit of ground current to 
trip the GFI.  Far less than what it takes to burn out one of those tiny 
matching networks.

  Usually semiconductor fail, either shorted or open at the time of "the 
event", but I do know that solid state devices can be "hurt" and may, or 
may not fail at some later date due to having been hurt.  So, I don't 
know if I've seen the last of this, if it's a series of "hurts" 
propagating from the previous failure(s), or even if they are related to 
the original lightening strike.
What I don't know is if the two antenna failures were related.  I'm 
fairly certain the second one was related to the UPS.

Knowing semiconductor circuits as I do, I fear I've not seen the last of 
its effects.
2 sets of finals and 2 big antennas, ignoring the computers, this is 
getting kinda expensive.
Anyone know how to check for future possibilities?


Roger (K8RI)

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