So you're saying that there's no info because it's far too simple - so why
bother to write it up in a text or app note?

Surely there is some small amount of "finesse" involved - whether it be in
the implementation of the modulation transformer or in trying to get the
optimum modulation levels in general. Nobody has covered this in a text?

I'm sure I could come up with some brute-force approach in doing the
high-level modulation using a kludge transformer (the "grenade" guys
are using simple line level transformers run "backwards")...

Either there's a more "scientific" approach to this or, as you suggest,
it's always done empirically??? Just wondering......

Bill

"John Smith" wrote in message
...
Just run the output of any audio source of ~5 watts into a "modulation
transformer" and have the B+ to the transmitter pass through its
secondary...

You can also construct an audio amplifier whose output power final
"modulates" (perhaps the B+ from the audio amps final transistor/tube) the
B+ to the xmitter... etc... ssb is by nature 2X-plus more efficient...
fm
supports greater sound quality...

I think detail about it is skipped simply because it is so easy to
affect....

Warmest regards,
John

Did you google for "plate modulation" or "grid modulation"... you should
turn something up there... even if you come across info for tube equip.,
the info is still just as accurate for transistor equip....

How about a trip to a used book store in your area to see what is available?

I see your point, I didn't say that correctly...

You are right, the information should be more available--its missing may
just be a lack of interest or anyone building am equip these days...

The pirate group and "freebanders" have groups, but you have to know someone
to be allowed into their discussions... I know "hidden chat rooms" exist on
IRC... but I have never been invited...

Warmest regards,
John
--
Marbles can be used in models with excellent results! However, if forced
to keep using all of mine up... I may end up at a disadvantage... I seem
to have misplaced some already!!!


"Netgeek" wrote in message
...
| So you're saying that there's no info because it's far too simple - so why
| bother to write it up in a text or app note?
|
| Surely there is some small amount of "finesse" involved - whether it be in
| the implementation of the modulation transformer or in trying to get the
| optimum modulation levels in general. Nobody has covered this in a text?
|
| I'm sure I could come up with some brute-force approach in doing the
| high-level modulation using a kludge transformer (the "grenade" guys
| are using simple line level transformers run "backwards")...
|
| Either there's a more "scientific" approach to this or, as you suggest,
| it's always done empirically??? Just wondering......
|
| Bill
|
| "John Smith" wrote in message
| ...
| Just run the output of any audio source of ~5 watts into a "modulation
| transformer" and have the B+ to the transmitter pass through its
| secondary...
|
| You can also construct an audio amplifier whose output power final
| "modulates" (perhaps the B+ from the audio amps final transistor/tube)
the
| B+ to the xmitter... etc... ssb is by nature 2X-plus more efficient...
| fm
| supports greater sound quality...
|
| I think detail about it is skipped simply because it is so easy to
| affect....
|
| Warmest regards,
| John
|
|

"Netgeek" wrote in message
...
So you're saying that there's no info because it's far too simple - so why
bother to write it up in a text or app note?

I suspect there's just not much interest in VHF AM. At least the HF AMers
have a world to find contacts in. Contacts on VHF are pretty much local,
and the probablility of finding a fellow AMer on VHF locally are vanishingly
small.

Indeed, why would someone use AM on VHF? If you don't like the sound of
sideband, use FM. If you simply want to get the message through, use
packet. If you want to operate under adverse conditions, use CW. AM has
precious few advantages in this day and age.

If you look in old issues of the Handbook, you will find designs for VHF AM
gear. If you hang around hamfests, you might uncover a twoer or sixer that
might still be coaxed into working. But mostly you will find tube gear from
an age when FM was complex and finicky.

But today, VHF FM is ubiquitous and cheap, so any AM equipment is playing to
a tiny niche.

...

"xpyttl" wrote in message

I suspect there's just not much interest in VHF AM. At least the HF AMers
have a world to find contacts in. Contacts on VHF are pretty much local,
and the probablility of finding a fellow AMer on VHF locally are
vanishingly
small.

snip

I can certainly see your point and I agree completely - insofar as it
applies to general applications. My interest is in the aviation bands where
AM is very much alive and well (and required). There's probably about
zip-nada-squat of interest happening in amateur VHF-AM for the reasons
you mention. But there was certainly some interesting traffic on the
airband frequencies here in Washington the other day when that nitwit in
the Cessna came breezing in....!!! 8-)

Bill

"Netgeek" wrote in message
...

"xpyttl" wrote in message

I suspect there's just not much interest in VHF AM. At least the HF
AMers
have a world to find contacts in. Contacts on VHF are pretty much
local,
and the probablility of finding a fellow AMer on VHF locally are
vanishingly
small.

snip

I can certainly see your point and I agree completely - insofar as it
applies to general applications. My interest is in the aviation bands
where
AM is very much alive and well (and required). There's probably about
zip-nada-squat of interest happening in amateur VHF-AM for the reasons
you mention. But there was certainly some interesting traffic on the
airband frequencies here in Washington the other day when that nitwit in
the Cessna came breezing in....!!! 8-)

Bill


Got bad news for you... A homebrew an aviation band transmitter is illegal.
And also you have to be a pilot or air traffic controller to operate an
aviation band transmitter - such transmitter must also pass specified
standards to be legal for use.

A reciever is a different matter of course.
There are quite a few manufacturers that make aviation band reciever kits.

73
Roger ZR3RC

"Roger Conroy" wrote in message

Got bad news for you... A homebrew an aviation band transmitter is
illegal.

Of course it is - and well it should be!!! I'm interested in the design
problems involved. If the results showed that something new, novel
or at least in the "better bang for the buck" category could be
constructed *and* it appeared to be of some interest to others I'd
seriously consider going to the trouble of FCC, FAA, TSO, RTCA,
NMEA, STC and whatever other relevant "LMNOP" alphabet
drills may be required. But that's quite a ways off and for now this
is more of an academic exercise than anything else, mostly because
I'm stunned at how little information is actually available. It's a
challenge.

And also you have to be a pilot or air traffic controller to operate an
aviation band transmitter - such transmitter must also pass specified
standards to be legal for use.

As noted above.......

I can appreciate you advising caution - but as I previously mentioned
(in the original post) I'm well aware of the potential "problems".

A reciever is a different matter of course.
There are quite a few manufacturers that make aviation band reciever kits.

But a real shortage of truly well-executed examples - or kits that happen
to satisfy my desired set of performance/features.......8-) I've already
built a 'couple - and then shredded them one functional block at a time so
that, eventually, the result is virtually a clean-sheet design. Sure, it's a
lot
of trouble - but entertaining...........8-)

Bill

Got bad news for you... A homebrew an aviation band transmitter is
illegal.

Bull$#!t.


And also you have to be a pilot or air traffic controller to operate an
aviation band transmitter

Bull$#!t.


- such transmitter must also pass specified
standards to be legal for use.

True.



A reciever is a different matter of course.
There are quite a few manufacturers that make aviation band reciever kits.

Learn to spell receiver.

Jim

Yes, well, why this is sure handy for manufacturers--it is not good for me
and the one I am building for my ultralight... grin

Warmest regards,
John

"RST Engineering" wrote in message
...


Got bad news for you... A homebrew an aviation band transmitter is
illegal.

Bull$#!t.


And also you have to be a pilot or air traffic controller to operate an
aviation band transmitter

Bull$#!t.


- such transmitter must also pass specified
standards to be legal for use.

True.



A reciever is a different matter of course.
There are quite a few manufacturers that make aviation band reciever
kits.

Learn to spell receiver.

Jim

This page shows a modulation xfrmr from an audio amp modulating a PA final
xistor--if that is difficult it is, if not--it is not... this is only a
simple drawing--but yeah, it is pretty much like that...

Warmest regards,
John
--
If "God"--expecting an angel... if evolution--expecting an alien... just
wondering if I will be able to tell the difference!

"Netgeek" wrote in message
...
| So you're saying that there's no info because it's far too simple - so why
| bother to write it up in a text or app note?
|
| Surely there is some small amount of "finesse" involved - whether it be in
| the implementation of the modulation transformer or in trying to get the
| optimum modulation levels in general. Nobody has covered this in a text?
|
| I'm sure I could come up with some brute-force approach in doing the
| high-level modulation using a kludge transformer (the "grenade" guys
| are using simple line level transformers run "backwards")...
|
| Either there's a more "scientific" approach to this or, as you suggest,
| it's always done empirically??? Just wondering......
|
| Bill
|
| "John Smith" wrote in message
| ...
| Just run the output of any audio source of ~5 watts into a "modulation
| transformer" and have the B+ to the transmitter pass through its
| secondary...
|
| You can also construct an audio amplifier whose output power final
| "modulates" (perhaps the B+ from the audio amps final transistor/tube)
the
| B+ to the xmitter... etc... ssb is by nature 2X-plus more efficient...
| fm
| supports greater sound quality...
|
| I think detail about it is skipped simply because it is so easy to
| affect....
|
| Warmest regards,
| John
|
|