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Ham radio Interference

The message
from "Graham." contains these words:

Ducks float so does wood, therefore ducks are made of wood,
No? Then why do you believe RF interferes with Audio?

RF can interfere with audio, video, servo controls, telemetry, or the
fillings in people's teeth.

Rod.

This is just an argument about semantics.
Sometimes it's useful look at it from the point of view of the
susceptibility
of the interfered apparatus, rather than the culpability of the radiating
apparatus,
but no doubt the man on the Clapham Omnibus would see it the way you do.

Just my t'uppence worth, but I think it'll add a useful perspective to
the OP's problem.

Around 12 or 15 years back, when I was an active G0 working the ten
metre band and my in-laws were still alive, they had a TV set (a Sanyo,
iirc) which gave a rock solid picture, even when I was running 100 watt
PEP SSB through a retuned Avanti Sigma 4 (a famously excellent CB
antenna) mounted less than 6 foot away from the TV antenna. However, the
sound was badly affected, even when the Tx was throttled back to a mere
2 watts PEP and no amount of 'braid breaking' would fix this. I figured
the audio amp was using the foot or so of internal wiring to the
speaker(s) as a recieving antenna for the 30MHz signal.

In the meantime, a Philips brand of TV we used in the room next door to
my in-laws (also fed from the same antenna) had no such problem on the
sound, although the picture would suffer a small degree of 'herring
bone' interference at the 100W PEP transmit levels.

A homebrewed (and designed) 50W per channel amplifier was likewise
immune (probably the result of it being a bridged output design and the
speaker leads being a balanced circuit, rather than the more susceptable
unbalanced one typical of the more common single ended design).

In the OP's case, I can't believe he's experiencing anywhere near the
same levels of RF field strength that our domestic TV sets were being
subjected to and I have to conclude that the problem is down to the lack
of a few copper's worth of ceramic caps and ferrite beads in his
equipment. Sadly, an all too common situation with a lot of mass
produced kit these days.

In the case of TV reception, a simple 'braid breaker' will often
decouple the 'Long Wire' effect of the TV antenna feeder from the
chassis (the usual route for such MF breakthrough problems).

Such a simple braid breaker can be made from a 2 metre 'flylead' wound
onto a 2 or 3 inch diameter form made from plastic or cardboard.
Alternatively, a set of ferrite sleeves or small rings can be slipped
over the co-ax or an in-line filter can be made from a short length of
thin 75 ohm co-ax wound onto a larger ferrite ring (2 or 3 inches
outside diameter with 4 or 5 spaced turns occupying no more than 3
quarters of the ring's circumference) with a male and female belling lee
plug fitted to the cable ends.

This type of remedy is a non-invasive one that can be tried without
risk to warranty or equipment safety. Indeed, the amateur in question
may offer to supply a braid breaker filter FoC by way of good will (it's
a cheap way to maintain a 'Quiet Life' ;-)

If the OP uses his noggin, he can engage the amateur in an amicable two
way conversation that turns the 'complaint' into a form of flattery (as
in "Hey, that beam antenna of yours must be good, 'cos it's only when
you point it my way that my TV set succumbs to breakthrough; you don't
happen to know how to cure the problem by any chance?" sort of thing.
;-)

BTW, the problem might even be down to nearby metalwork with corroded
joints acting as a rectifier, distorting the resulting amateur band
transmission current flow that would otherwise be totally harmless and
produce harmonics extending into the UHF band, directly interfering with
the TV signal.

Often the nearby metalwork will be the support mast or lashing kit for
the TV antenna itself. In this case, no amount of "braid breaking" will
have any significant effect on the problem which needs to be directly
addressed (ie repair of the afflicted TV antenna installation - not an
entirely bad thing since such corroded joints are often the precursor to
catastrophic failure of the TV antenna installation come the next high
wind).

Most radio hams appreciate the need for co-operation with their
neighbours when such issues arise and will volunteer to help find a
solution when approached in a civil manner, Indeed the "Pirate CB
operator" is even more likely to offer such help since his position is
so much more precarious, legally speaking, than his radio ham
counterpart.

At the end of the day, you don't want to involve OFCon unless you
really have no further recourse.

HTH

--
Regards, John.

Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

Ham radio Interference

Dave H wrote:
I have a Ham Radio enthusiast living some 200 yards away with a big set
of aerianalia......

I doubt this won't be of any help to you but others may appreciate the
story ...

I first knew Tom 50 years ago. He had a G3K** call sign.

To put this into perspective, the only way to get a licence then was,
not only to pass the Radio Amateurs' Exam, but a stiff morse test as
well. Those three letters at the end of a call sign didn't progress very
rapidly in those days! As a guide, the Best Man at my wedding, 15 years
later, was G3RZP. (Anybody recognise this call?)

Anyway, back to Tom. Before I knew him, he'd done some long distance
lorry driving. No Motorways, very few dual carriageways and, in any
case, no commercial vehicle was allowed to travel faster than 40 mph!
(That included the car-based 5cwt van!)

Large antennae - particularly for the HF bands - were a dead give-away
if you were an amateur in those days - not much VHF around then!.

Often, his wife would answer a knock at the door during the course of
the evening and find a complete stranger on the step, who would regale
her thus:

"where's that bleedin' 'usband of yours? I know it's 'im - 'im and 'is
bloody 'am radio. Our telly's bloody awful tonight - we can't watch a
bleedin' thing! I wannit off, and I wannit off right now!!"

Tom's wife would then patiently explain that he was in Birmingham or
Bristol or somewhere equally distant and wouldn't be back to the
following day...

Ham radio Interference

Terry Casey wrote:

Often, his wife would answer a knock at the door during the course of
the evening and find a complete stranger on the step, who would regale
her thus:

"where's that bleedin' 'usband of yours? I know it's 'im - 'im and 'is
bloody 'am radio. Our telly's bloody awful tonight - we can't watch a
bleedin' thing! I wannit off, and I wannit off right now!!"

Tom's wife would then patiently explain that he was in Birmingham or
Bristol or somewhere equally distant and wouldn't be back to the
following day...

Very wise in the circumstances, whether he was in or not.

Ham radio Interference

In message , Norman Wells
writes
Terry Casey wrote:

Often, his wife would answer a knock at the door during the course of
the evening and find a complete stranger on the step, who would regale
her thus:
"where's that bleedin' 'usband of yours? I know it's 'im - 'im and
'is
bloody 'am radio. Our telly's bloody awful tonight - we can't watch a
bleedin' thing! I wannit off, and I wannit off right now!!"
Tom's wife would then patiently explain that he was in Birmingham or
Bristol or somewhere equally distant and wouldn't be back to the
following day...

Very wise in the circumstances, whether he was in or not.

In the days of Band 1, summertime sporadic-E interference was often
blamed on some hapless local radio amateur. The problem is, once you
have 'caused' interference, from then on, all interference tends to get
blamed on you. This can happen even when the efforts of the amateur to
'cure' the interference have resulted in the 'sufferer' ending up with a
far better TV picture than he had previously, and the amateur is many
miles from home. Some people are so ungrateful.
--
Ian

Ham radio Interference

"tony sayer" wrote in message
...
In article , charles
I think Charles ... your older than me;!...

He's more sprightly.

Bill

Ham radio Interference

"Terry Casey" wrote in message
...
Dave H wrote:
"where's that bleedin' 'usband of yours? I know it's 'im - 'im and 'is
bloody 'am radio. Our telly's bloody awful tonight - we can't watch a
bleedin' thing! I wannit off, and I wannit off right now!!"

Tom's wife would then patiently explain that he was in Birmingham or
Bristol or somewhere equally distant and wouldn't be back to the following
day...

When a radio amateur moves house or intends to start a station, he should
install a big aerial at least six months before he buys and radio equipment.
Then, when the complaints come in, he can show the complainer the end of the
cable, with no equipment attached.

Bill

Ham radio Interference

Dave H wrote:
I have a Ham Radio enthusiast living some 200 yards away with a big set
of aerianalia. When he turns this in my direction and talks to his
contact, my picture on Sky jumps all over the place to the extent it is
unwatchable. Just like having the vertical hold set wrong. The sound on
my amplifier also cuts out when he is talking...

(Turned on the electric keyboard the other day and there he was in
glorious SSB blasting out from the speakers)

More years ago than I care to remember, I heard a story about a church
in Worcestershire which had a public address system installed (quite
rare, in those days.)

The first Sunday it was used, the vicar got up in the pulpit and proudly
flicked the microphone switch to 'on'.

From the speakers came: "It's 12 o'clock at home and away and time for
Two-Way Family Favourites ...!"

(Something to do with there being a 400kW transmitter nearby, I
understand ...)

Terry

Ham radio Interference

"Roderick Stewart" wrote in
message .myzen.co.uk...
In article , Steve Terry wrote:
Ducks float so does wood, therefore ducks are made of wood,
No? Then why do you believe RF interferes with Audio?

RF can interfere with audio, video, servo controls, telemetry, or the
fillings in people's teeth.
Rod.

Nope, audio, video, servo controls, telemetry, or the fillings
in people's teeth. can receive RF when they are not designed to

I'm shocked at the lack of understanding of cause and effect
on a technical NG

Steve Terry

Ham radio Interference

"Bill Wright" wrote in message
...

"Terry Casey" wrote in message
...
Dave H wrote:
"where's that bleedin' 'usband of yours? I know it's 'im - 'im and 'is
bloody 'am radio. Our telly's bloody awful tonight - we can't watch a
bleedin' thing! I wannit off, and I wannit off right now!!"

Tom's wife would then patiently explain that he was in Birmingham or
Bristol or somewhere equally distant and wouldn't be back to the
following day...

When a radio amateur moves house or intends to start a station, he should
install a big aerial at least six months before he buys and radio
equipment. Then, when the complaints come in, he can show the complainer
the end of the cable, with no equipment attached.

Very true, I got more than one knock on my door before I was
licensed when all I had connected to my aerial was an R107
WWII ships receiver.

Mind you, the home-built valve super-regenerative sets I built
while I was still at school *did* have the potential to cause
interference.

--
Graham.

%Profound_observation%