Ham radio Interference

"Bill Wright" wrote in message
...

"Norman Wells" wrote in message
...
charles wrote:

"'Wiv a ladder and some glasses,
You could see to 'Ackney Marshes,
If it wasn't for the 'ouses in between."

In Yorksher it doesn't sound right unless you put
"'Wiv a ladder and some glarsers,
You could see to 'Ackney Marshes,
If it wasn't for the 'ouses in between."

A Yorksher version might be

"'Wiv a ladder and some glasses,
You could see the M1 crashes
If it wasn't for the 'ouses in between."

On Listen with Mother they used to chant, archly,

"Ride a cock horse
To Banbury Cross"

Which rhymed perfectly, but round these parts the children would sing

"Ride a cock 'oss
To Banbury Cross"

which also rhymed perfectly. But it was a completely different rhyme!

Anyone still with me?

Sort of, but only by our fingertips.

"Bill Wright" wrote in message
...

"Every night at bedtime my wife has a headache. It's that damned radio ham
next door!"

She gets exhausted SWAAAARING his twig!
--
;-)
73 de Frank Turner-Smith G3VKI - mine's a pint.
http://turner-smith.co.uk

Bill Wright said the following on 02/03/2009 17:53:
On Listen with Mother they used to chant, archly,

"Ride a cock horse
To Banbury Cross"

Which rhymed perfectly, but round these parts the children would sing

"Ride a cock 'oss
To Banbury Cross"

which also rhymed perfectly. But it was a completely different rhyme!

Anyone still with me?

You should go to the Olymic village which is Banbury, on account of
everone wearing tracksuits!

It would have a Carnish lilt to it and so be another version.

"tony sayer" wrote in message
...
In article , Graham.
scribeth thus


"tony sayer" wrote in message
...
In article , Woody
scribeth thus
[snip]
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.


Another form of semi conductor

More found on radio comms sites...



I've long thought this to be an urban myth. I'm in my 40th year in the
mobile radio business and 31st as a field tech for a large part of which
I covered the whole of the north of England and north Wales and I have
never come across this problem.


It does happen .. especially on crowded shared sites with no bandpass
filtering or circulators etc..

Mind you the number of PMR shared sites is now in decline so perhaps not
as noticeable as it once was and sometimes it goes unnoticed and people
just put it down to interference..

Now a woman near Scarborough that could hear the local council depot
(which did not have a Tx on site) on her radio, cassette recorder,
microwave, toaster...........



Perhaps she was in need of some "attention"......

I can't think of any PMR system that would be resolved as intelligible
speech by simple demodulation.


Depends on how long go AM systems were quite fashionable sometime
ago..


Hover as this might have been -imaginary demodulation- ...

Yes, I think I have mentioned this before, I came across this
when a woman called into the TV repair shop where I was
working a few years ago and asked if her upstairs neighbours'
Sky dish could affect her hi-fi. Each time I offered a rational
explanation as to what might be happening she would up
the ante with more and more bizarre scenarios about the
motives of the owner of the dish, including it spying on her
via her own brown-goods.
She was totally paranoid.

--
Graham.

%Profound_observation%

On Mon, 02 Mar 2009 20:18:30 +0000, Graham. wrote:
asked if her upstairs neighbours' Sky dish could affect her hi-fi.

There does appear to be a certain irrational fear of satellite dishes
amongst certain members of the population.

Does it all originate from the 1960s and TV shows like "A for Andromeda"?

"Spike" wrote in message
...

Spike wrote:

There's a fairly simple calculation on page 3 of this url, and on page
4 there's some figures for the immunity standards, which might be of
interest to the OP:

http://www.docstoc.com/docs/3639693/...embers-Leaflet

Bad form, etc

A quick calculation shows that 4kW into a 6dB beam on say 20m will
give field strengths 10V/m at that distance, and rather less than a
kW for a 15 dB gain yagi on 2m. These set-ups are feasible with
commonly-available Amateur equipment.

Where do you get the 4kW from?
4kW PEP to the aerial would be illegal in every country I can think
of. Here it's 400W (26dBW) on most bands, but it is true that with
only two exceptions, ERP is not specified in the schedule, and any
aerial gain is a bonus.

I am not saying that some don't flout the rules, but you don't
make it clear that the scenario you give would be illegal full-stop.


--
Graham.

%Profound_observation%

On 2009-03-02, Bill Wright wrote:

"Len GM0ONX" wrote in message
...
Jeff wrote:
The truth is harsh but Jeff is right. Its almost certain that your
equipment is at fault. OFCOM can help with the TV by fitting high pass
filters but you may be on your own with the electric keyboard as it should
designed not to pick up radio signals.

Hams will always take this view. I dare they are 90% right. But in my
experience anyone living in the sort of field strength generated by 100s of
Watts multipled by the gain of a long beam is inevitably going to have
problems. Every piece of electonic equipment they buy might suffer
interference, and how can Joe Bloggs be expected to fit caps across all the
transistor junctions in his new bit of kit?

What needs to happen is both parties need to work together to find
the correct solution, for this particular case. Yes, there are some
"default" things to try etc, highpass filters on the antenna input
to the Sky box, and/or lowpass filters on the transmit antenna line.

Or maybe the Amateur can reduce power during the times the other party
is likely to be watching Television ?

I think it's time that the law was changed. When the present regulations
were made home electronics amounted to much less than they do now. It is
just plain antisocial to generate that sort of field strength if you live on
in high density housing area. Anyone wanting to pursue their hobby with that
sort of power should move house, to somewhere where there are no neighbours.
The law should be altered so that no amateur can put more than a certain
field strength into any residential property except his own.

This is not a panacea, and interference can be caused by very low power.
My grandparents used to have a TV that would *power off* when I keyed up
using a 1 Watt Handheld on 144MHz! That was fun! More recently, I
discovered my home cinema sub-woofer didnt appreciate 25 or 50 Watts
at 10MHz under certain circumstances!

A Signal of Field strength x may cause interference at y MHz, but not
at z MHz.

Interference can come thru other sources than the RF, for instance, it
can be induced via mains wiring, or caused by some dodgy grounding. No
amount of field strength limits will help there.



"Legally" the Amateur Radio Enthusiast may be correct that it's the
user's equipment problem. IMHO, that doesn't mean he cant/wont/shouldn't
work with the OP to resolve the situation to the satisfaction of both
parties.

The truth is that interference problems can be very wierd(tm), and
do go both ways. 802.11b co-exists on (admittedly secondary allocated)
amateur radio band. Older plasma TVs have been known to wipe out HF.
Microwave ovens put out quite a broadband noise (try using your WiFi
while cooking dinner *grin*)

The truth is that some interference cases can just be "weird" (tm)
Compromise fellas, Compromise and work together to fix it!


Iain

wrote in message
...
On Mar 2, 12:06 pm, "Bill Wright"
wrote:
"Ian Jackson" wrote in message
...
snip
I think that the health hazards associated with high power amateur
radio operation in built up urban areas also needs to be taken into
account.

After you take into account the very real heath hazard of radiated
energy of the big yellow thing in the sky first
It's demonstrably killed and damaged more people than RF ever could
So who's for banning the sun?

The FCC has introduced and assessment programme (FCC form 610)
http://www.cfht.hawaii.edu/~veillet/rfsaf610.html which requires
compliance with various power limits and field strengths.


What else go you expect from the land of the politically correct,
and creationism?

Steve Terry

"Bill Wright" wrote in message
...
wrote in message
...
How long before neighbours of amateur radio operators with large
antenna arrays (or those experiencing EMI problems) start to use this
tactic.

"Every night at bedtime my wife has a headache. It's that damned radio ham
next door!"
Bill

Tell him to leave your Wife alone then!

Steve Terry

Graham. wrote:


"Spike" wrote in message
.. .

Spike wrote:

There's a fairly simple calculation on page 3 of this url, and on page
4 there's some figures for the immunity standards, which might be of
interest to the OP:

http://www.docstoc.com/docs/3639693/...embers-Leaflet

Bad form, etc

A quick calculation shows that 4kW into a 6dB beam on say 20m will
give field strengths 10V/m at that distance, and rather less than a
kW for a 15 dB gain yagi on 2m. These set-ups are feasible with
commonly-available Amateur equipment.

Where do you get the 4kW from?
4kW PEP to the aerial would be illegal in every country I can think
of. Here it's 400W (26dBW) on most bands, but it is true that with
only two exceptions, ERP is not specified in the schedule, and any
aerial gain is a bonus.

I am not saying that some don't flout the rules, but you don't
make it clear that the scenario you give would be illegal full-stop.

I rather thought that Radio Amateurs could work out the legalities for
themselves.

I merely crunched some numbers to show what was possible, and that
exercise showed that the equipment necessary easily fell within the
bounds of availability.

--

from
Aero Spike
Not a member of the RSGB for 50 years 1959 - 2009