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Old March 23rd 07, 10:40 AM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?

I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)


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Old March 23rd 07, 03:57 PM posted to rec.radio.amateur.homebrew
Arv Arv is offline
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Default Turn portable radio into transmitter- can it be done?

On 23 Mar, 03:40, "Kevin J." wrote:
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)


Oh Wow! You opened up a whole can of worms with this post.

1) What part of Part-15 does not allow kits? I think it only
requires low power levels (depends on frequency) and compliance with
antenna size restriction (also depends on frequency). You can
purchase Part-15 compliant transmitters, Part-15 compliant
(supposedly) kits, or could build your own Part-15 compliant
transmitter. There is, as far as I know, no formal "Type Approval"
process for Part-15 transmitters. If you purchase a pre-built Part-15
compliant transmitter, be sure it contains a label by the manufacturer
stating that it complies with Part-15 regulations. If you build a
kit, or build something up from a magazine article or your own design,
you will be responsible for insuring that it is Part-15 compliant.

2) It would be possible to modulate the internal local oscillator on
one receiver and use it as a transmitter to other radios, but that is
somewhat complex and does require soldering, component removal,
component addition, etc. Again, you would be responsible for insuring
that the resulting transmitter device was Part-15 compliant.

3) For local in-house use you only need a few milliwatts of RF
power. There are kits available for that, or you could build up your
own crystal oscillator and modulator circuit. Just be sure to keep
the power and antenna size within FCC Part-15 requirements for the
frequency you are using.

4) Ham Radio is not the answer for what you want to do, because ham
regulations in the US do not allow "broacasting" (i.e one-way-only
transmission) and also do not allow music transmission.

Arv
_._

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Old March 23rd 07, 04:00 PM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?

Kevin J. wrote:
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)


I did that as a kid with tube type radio. I moved the connections to the
antenna coil
to replace the first IF coil. I connected the audio to the grid in place
of the antenna
coil. You have to re tune the oscillator and antenna coils to be on the
same frequency.

On tube type radios this was easy but on newer radios with a circuit
board, I don't know.

Bill K7NOM
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Old March 23rd 07, 10:15 PM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?

That reminds me of the Halicrafters S22-R I had upstairs in my bedroom when
a boy.
By clipping a wire on to the IF (1.6 MHz ), I was able to listen downstairs
on a MW receiver.

Once I was staying at a holiday camp and was being kept awake by a loud
radio in the adjoining chalet.
I touched the TV aerial lead on the local oscillator of my Murphy portable
and wiped out their signal.
After a while they gave up and switched it off.

I was so pleased with myself I couldn't get off to sleep !



Taking a valve receiver as an example, I suppose the loudspeaker could be
used as a microphone
and the local oscillator amplitude modulated.
Some soldering might be required !

Russ


"Kevin J." wrote in message
oups.com...
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)



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Old March 24th 07, 10:11 AM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?

On Mar 23, 11:40 am, "Kevin J." wrote:
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)


Will not be muuuuch easy for homebrewing a simple FM transmitter
instead ?
http://tacashi.tripod.com/elctrncs/s...r/smplfmtr.htm



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Old March 24th 07, 03:32 PM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?

Kevin J. wrote:
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)

As a kid I fooled around with radio circuits. I built a solder less
breadboard for building and tearing down circuits that had 4 octal
sockets and tons of farinstock clips for interconnecting parts. I had
quit a few old tubes in the junk box when an old time radio repair man
gave me what was left of the contents of his tube caddies.

So I wound an oscillator coil around a cardboard tube from toilet paper
and built a Hartly oscillator with a 6F6G running with 300 volts on the
plate. It was modulated by another 6F6G choke coupled to the
oscillator. So I was running near 1-2 WATTS input. I connected several
feet of wire as an antenna to the cathode of the oscillator tube and
tuned it to the middle of the broadcast band at an empty spot on the
dial. A crystal phono pickup directly drove the modulator tube.

I would put on an LP record and take a transistor radio outside to see
how for out it got. It covered the whole block! Probably illegal
power, but I never used it long enough for anybody to notice. Without
the antenna, I could still hear it anywhere in the apartment house.
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Old March 24th 07, 07:46 PM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?

On Mar 24, 6:32´┐Żam, ken scharf wrote:
Kevin J. wrote:
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.


Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)


As a kid I fooled around with radio circuits. *I built a solder less
breadboard for building and tearing down circuits that had 4 octal
sockets and tons of farinstock clips for interconnecting parts. *I had
quit a few old tubes in the junk box when an old time radio repair man
gave me what was left of the contents of his tube caddies.

So I wound an oscillator coil around a cardboard tube from toilet paper
and built a Hartly oscillator with a 6F6G running with 300 volts on the
plate. *It was modulated by another 6F6G choke coupled to the
oscillator. *So I was running near 1-2 WATTS input. *I connected several
feet of wire as an antenna to the cathode of the oscillator tube and
tuned it to the middle of the broadcast band at an empty spot on the
dial. *A crystal phono pickup directly drove the modulator tube.

I would put on an LP record and take a transistor radio outside to see
how for out it got. *It covered the whole block! *Probably illegal
power, but I never used it long enough for anybody to notice. *Without
the antenna, I could still hear it anywhere in the apartment house.


Few in here were around when the "phono oscillator" was a
consumer electronics product...in the 1940s. :-)

Back then there were few "radios" (AM broadcast receivers)
that had any audio input jack on the back and "records"
(78 RPM discs) were the new thing for the home.
Phonographs (self-contained units) sometimes had such
oscillators...usually one-tube AM oscillators that could be
set to an unoccupied spot on the AM BC band. No wires
to connect! :-)

These were neat little projects for the teener back then,
letting them play grown-up "broadcaster." I was one of
those for a few days back then...until my Dad, coming
home from work, saw my buddy carrying my portable
receiver and listening to my voice coming out of it...:-)

Not a technically-difficult task to build one, even very
low-power. Today's wireless FM microphone is more
complex, although not too much. With transistors or
ICs, an AM wireless mike can be made, with battery
supply, in most any large microphone enclosure. No
mike cable needed.

It's USE is a fad, little more. The FM mike in a Karaoke
setup is much more entertaining in a party environment.
These "AM broadcast" thingies are good as minor profit
devices for kit makers but very limited due to today's
[USA] Part 15 limitations.

73, Len AF6AY

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Old March 27th 07, 03:30 AM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?


"Kevin J." wrote in message
oups.com...
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)


Any modification would probably require more skill than assembying a part15
tx kit.

Jimmie


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Old March 27th 07, 12:58 PM posted to rec.radio.amateur.homebrew
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Default Turn portable radio into transmitter- can it be done?

On Mar 23, 5:40 am, "Kevin J." wrote:
I have more portable radios than I know what to do with and was
wondering if I could somehow convert one of them for use as an
extremely low-powered AM transmitter for use around my apartment. I
need only a range of 10 feet or so and I really don't want to buy any
sort of kit as Part-15 regulations in the US prohibit their use but do
allow homebuilt units. I had one of those toys called a Wild Planet
Radio DJ that was FCC type-approved but it got misplaced in my last
move and now my old-time radio shows are just sitting there waiting to
return to life on my antique radios.

Or, should doing that prove impractical, how hard is it to learn how
to solder? :-)


A typical 70's/80's AM transistor radio will have several parts that
will be usable (e.g. oscillator coil, tuning cap, lots of small
resistors and transistors, an audio amp maybe with output transformer
that could be used for modulation) either as raw parts or as
subassemblies. But you aren't going to do it without soldering, and
probably judicious use of exacto knives too!

Tim.



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