In message , Jeefaw K. Effkay
writes
On 06/02/2015 14:47, FranK Turner-Smith G3VKI wrote:
"Jeff" wrote in message ...
FM has always been a legal mode for 80m in the UK, it's just that nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

Well perhaps not 'always'. FM was not allowed prior to about 1952.

Jeff

When was FM first invented? BBC broadcast FM started in 1955.

http://en.wikipedia.org/wiki/Edwin_Howard_Armstrong

I told you Google would tell us.
--
Ian

"FranK Turner-Smith G3VKI" wrote in message
news
FM has always been a legal mode for 80m in the UK, it's just that nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

I am sure every country has slightly differant rules. As I don't operate FM
below the 10 meter band I am not up on the current regulations in the US
where most of the stations I was hearing are at. At onetime in the US we
could use something like around 2 to 3 khz deviation on 80 meters I think .
That used to be called somethink like sliver band. Maybe still can.
However some of those on 3.85 MHz were way wider than that. I think that
below 30 MHz it is only on some portions of 10 meters that deviations as
wide as 5 KHz can be used in the US.

As I was saying above, I am not sure those AM / FM signals are legal in the
US, but don't really care. It is good that the hams have decided on a
frequency to meet and have fun with the old sets.

de KU4PT

On 06/02/15 12:39, Jeff wrote:

FM has always been a legal mode for 80m in the UK, it's just that nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

Well perhaps not 'always'. FM was not allowed prior to about 1952.

There was an adaptation of the WS19 (I think it was the WS32) that used
FM instead of AM, to test the use of FM on the battlefield. I guess it
was unsuccessful or other considerations mitigated against it, because
it wasn't adopted in that form, but some manpack sets and WS19 candidate
replacements were FM. I think that only about 100 WS32 were made.


--
Spike

"Hard cases, it has frequently been observed, are apt to introduce bad
law". Judge Rolfe

On Fri, 6 Feb 2015, FranK Turner-Smith G3VKI wrote:

"Ralph Mowery" wrote in message
...
"Michael Black" wrote in message
news:alpine.LNX.2.02.1502051950290.19867@darkstar. example.org...
On Thu, 5 Feb 2015, Ralph Mowery wrote:
I don't have any of the very old gear, but every so often I listen to the
hams around 3.85 MHz. that use the old military and AM gear. While I
don't think it is really legal (and don't really care) some of those AM
transmitters sound beter if I switch to FM on my Icom 746 pro. I think
when they were made they seem to put out about as much FM as AM.

That's weird. I thought those hardcore AMers wanted purity, and took
effort to ensure they were putting out a good signal. They sure aren't
using modulated oscillators, and I don't think anything where the
modulation would get back to the oscillator.

There may be two kinds of people using AM. One for 'good quality AM' ,but
the other is using mainly the military gear from around the WW2 era or so.
Maybe even before that if they can find it. That is the stuff that can
contain about as much FM as it does AM. The power supplies are often
feeding the oscillator as well as the final stages and not regulated very
well if at all. That probably helps modulate the transmitter to have a lot
of FM in the signal.

FM has always been a legal mode for 80m in the UK, it's just that nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a problem.

But Ralph is complaining about a signal that is both AM and FM.

INtentional FM is different from incidental FM.

Certainly in the US (and I assume Canada), rules were in effect quite a
few decades ago about the stability of a signal. There was a point where
a signal had to be as stable as a crystal controlled signal on the HF
bands, which caused a shift to crystal control, I think that was even
before WWII. So incidental FM would seem to be out of the question after
that. It was only after WWII when things got crowded and better
techniques came along that VFOs made a comeback, obviously much better
built and stable than the variable oscillators of the old days. (And the
same sort of rule followed as the move up to higher frequencies.
Modulated oscillators would work the higher frequencies initially, then
the rule for better stability would come in, and the modulated oscillators
would move to the next higher band, and so forth).

If a signal is putting out both FM and AM, it is either doing it by
accident, and needs fixing, or is some weird form or modulation, that the
rules would either have a separate classification for, or a rule against
it.

Michael

On Fri, 6 Feb 2015, Ralph Mowery wrote:


"FranK Turner-Smith G3VKI" wrote in message
news
FM has always been a legal mode for 80m in the UK, it's just that nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

I am sure every country has slightly differant rules. As I don't operate FM
below the 10 meter band I am not up on the current regulations in the US
where most of the stations I was hearing are at. At onetime in the US we
could use something like around 2 to 3 khz deviation on 80 meters I think .
That used to be called somethink like sliver band. Maybe still can.
However some of those on 3.85 MHz were way wider than that. I think that
below 30 MHz it is only on some portions of 10 meters that deviations as
wide as 5 KHz can be used in the US.

There was definitely a period when FM was promoted for the HF bands, not
just 10Metres as later happened. Hallicrafters had an CW/FM HF
transmitter at one point, obviously it was a whole lot simpler to add FM
to a transmitter than AM. I thought SOnar also had some HF FM
transmitters in the same period, but looking around, I've yet to find what
I thought I'd read about that years ago.

Even later, the ARRL Handbook had a 220MHz transmitter into the seventies
that was primarily a CW transmitter (or exciter for a separate plate
modulated amplifier, but it also had narrow deviation FM, just in case
someone wanted to do phone up there. But the expectation was to use slope
detection, this wasn't part of the "move commercial 2way FM radios to the
ham bands for channelized operation", that came later.

Michael

"Michael Black" wrote in message
news:alpine.LNX.2.02.1502061353050.21109@darkstar. example.org...
But Ralph is complaining about a signal that is both AM and FM.

INtentional FM is different from incidental FM.

Certainly in the US (and I assume Canada), rules were in effect quite a
few decades ago about the stability of a signal. There was a point where
a signal had to be as stable as a crystal controlled signal on the HF
bands, which caused a shift to crystal control, I think that was even
before WWII. So incidental FM would seem to be out of the question after
that. It was only after WWII when things got crowded and better
techniques came along that VFOs made a comeback, obviously much better
built and stable than the variable oscillators of the old days. (And the
same sort of rule followed as the move up to higher frequencies. Modulated
oscillators would work the higher frequencies initially, then the rule for
better stability would come in, and the modulated oscillators would move
to the next higher band, and so forth).

If a signal is putting out both FM and AM, it is either doing it by
accident, and needs fixing, or is some weird form or modulation, that the
rules would either have a separate classification for, or a rule against
it.

I was not really complaining about the signal, just noting that it sounded
beter on FM than AM.

What might have been state of the art around 1930 or 1940 is probably not
legal now. Just as the old spark gap transmiters are not legal any more.
The station was suspose to be using AM, but probably the power supply was
not regulated enough that fed the audio amp and also the VFO so that the
changing of the VFO voltage was enough to FM the signal.

As you say Michael the design was for AM, but some of the old sets seem to
put out as much FM as they did AM. That was just the way it was 60 or 70
years ago. Especially some of the portable military gear.

Anyway I have no complaints about some guys having fun with the old gear as
long as they stay on or very near one frequency like they do.

"Spike" wrote in message
...
On 06/02/15 12:39, Jeff wrote:
FM has always been a legal mode for 80m in the UK, it's just that nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

Well perhaps not 'always'. FM was not allowed prior to about 1952.

There was an adaptation of the WS19 (I think it was the WS32) that used FM
instead of AM, to test the use of FM on the battlefield. I guess it was
unsuccessful or other considerations mitigated against it, because it
wasn't adopted in that form, but some manpack sets and WS19 candidate
replacements were FM. I think that only about 100 WS32 were made.

To ensure compatibility it would have been necessary to swap all the
military AM radios to FM at the same time.
The middle of a global war is not the time to make changes on that scale,
especially as the advantages of doing so seem minimal.
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.co.uk

In message , FranK Turner-Smith G3VKI
writes
"Spike" wrote in message
...
On 06/02/15 12:39, Jeff wrote:
FM has always been a legal mode for 80m in the UK, it's just that nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

Well perhaps not 'always'. FM was not allowed prior to about 1952.

There was an adaptation of the WS19 (I think it was the WS32) that
used FM instead of AM, to test the use of FM on the battlefield. I
guess it was unsuccessful or other considerations mitigated against
it, because it wasn't adopted in that form, but some manpack sets and
WS19 candidate replacements were FM. I think that only about 100 WS32
were made.

To ensure compatibility it would have been necessary to swap all the
military AM radios to FM at the same time.

The middle of a global war is not the time to make changes on that
scale, especially as the advantages of doing so seem minimal.

Very true. Weren't there all sorts problems later on when some of our
emergency services got radio, and some areas used and AM, and some used
FM?

IIRC, most WW2 gear used simple 'Lo-Fi' forms of AM modulation (grid or
screen-grid), and not hi-level plate and screen (which requires more
valves, more current drain, a heavy mod transformer etc). As such, the
component count would be similar to FM equipment.

Also, AM detection is probably more tolerant of mistuning than FM.
There's also the reason why Air Traffic Control use AM and not FM - ie
lack of capture effect.


--
Ian

On 07/02/15 13:07, Ian Jackson wrote:
In message , FranK Turner-Smith G3VKI
writes
"Spike" wrote in message
...
On 06/02/15 12:39, Jeff wrote:
FM has always been a legal mode for 80m in the UK, it's just that
nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

Well perhaps not 'always'. FM was not allowed prior to about 1952.

There was an adaptation of the WS19 (I think it was the WS32) that
used FM instead of AM, to test the use of FM on the battlefield. I
guess it was unsuccessful or other considerations mitigated against
it, because it wasn't adopted in that form, but some manpack sets
and WS19 candidate replacements were FM. I think that only about 100
WS32 were made.

To ensure compatibility it would have been necessary to swap all the
military AM radios to FM at the same time.

The middle of a global war is not the time to make changes on that
scale, especially as the advantages of doing so seem minimal.

Very true. Weren't there all sorts problems later on when some of our
emergency services got radio, and some areas used and AM, and some used FM?


The various different services, Police, Ambulance, Fire, Coast Guard,
were on different frequencies so AM/FM was really of little consequence.

One of the, supposed, ideas behind 'Airwave' is that they can all be
linked but I am not sure how far this has actually been achieved, if at
all. Certainly the functionality that Kent Police were expecting is
still a pipe dream, based on some casual chats with end users who are
most unimpressed.


Compare that to some of the systems in place in the USA, where (even in
small towns) officers can access key information from a vehicle mounted
computer. (No, I've not been 'checked', I know someone who worked on the
systems.)

I have seriously wondered if the considerable delay in 'pushing' the
take up of the 'old' UHF emergency service frequencies wasn't, in part,
caused by concern that it may be necessary to 'rethink' the reliance on
Airwave. After all, I attended a presentation by OFCOM when it was still
not sure if it was the RA or OFCOM ;-) when they were, supposedly, about
to 'fill' the old frequencies with waiting users. Here we are, over a
decade on, and they are still 'talking'. Quite a feat, even for OFCOM ;-)


Also, AM detection is probably more tolerant of mistuning than FM.
There's also the reason why Air Traffic Control use AM and not FM - ie
lack of capture effect.


I suspect it is more historical Ian. Aircraft VHF sets are not VFO
controlled, these days there will be PLL but in the past they were
crystal controlled.

On 2/7/2015 8:07 AM, Ian Jackson wrote:
In message , FranK Turner-Smith G3VKI
writes
"Spike" wrote in message
...
On 06/02/15 12:39, Jeff wrote:
FM has always been a legal mode for 80m in the UK, it's just that
nobody
normally uses it intentionally.
Provided you're using no more bandwidth than normal AM I can't see a
problem.

Well perhaps not 'always'. FM was not allowed prior to about 1952.

There was an adaptation of the WS19 (I think it was the WS32) that
used FM instead of AM, to test the use of FM on the battlefield. I
guess it was unsuccessful or other considerations mitigated against
it, because it wasn't adopted in that form, but some manpack sets
and WS19 candidate replacements were FM. I think that only about 100
WS32 were made.

To ensure compatibility it would have been necessary to swap all the
military AM radios to FM at the same time.

The middle of a global war is not the time to make changes on that
scale, especially as the advantages of doing so seem minimal.

Very true. Weren't there all sorts problems later on when some of our
emergency services got radio, and some areas used and AM, and some used FM?

IIRC, most WW2 gear used simple 'Lo-Fi' forms of AM modulation (grid or
screen-grid), and not hi-level plate and screen (which requires more
valves, more current drain, a heavy mod transformer etc). As such, the
component count would be similar to FM equipment.

Also, AM detection is probably more tolerant of mistuning than FM.
There's also the reason why Air Traffic Control use AM and not FM - ie
lack of capture effect.



Actually not. Aircraft worldwide were using AM radios before FM became
popular. To change would require every radio-equipped airplane in the
world, from Cessna 150's to Antonov An-225's, change at the same time,
as well as all land-based stations including ATC, Flight Service
Stations, Unicoms, and even handhelds on the tarmac.

Plus, with the 8.33Khz channel spacing, deviation would be limited to
about +/- about 3Khz. Even with the old 25Khz channel spacing (allowing
about +/- 10Khz deviation), there is no clear advantage to FM over AM.
Fidelity is not a concern for the aircraft band.

It isn't going to happen It's going to take least 13 years just to
get new NextGen navigation system installed in aircraft in the United
States.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================