Discussion:
AM BC band micro-transmitter
(too old to reply)
Engineer
2006-08-02 02:56:46 UTC
Hi, Vacuumlanders.
I've seen this topic before but can't recall the outcome... Anyway, I'm
looking for a 100 mW (+/-) broadcast band AM transmitter kit so that I
can play my OTR CD's through my restored old time radios - from an
antenna in, not just jumpering the audio and faking it.

I have found the Ramsey Kits, in particular models AM1C (US$34.95) and
AM25 (US#99.95.) How good are they?

I also recall another brand that may have the numbers "3000" in the
name, but I can't be sure. IIRC, it seemed to get rave reviews.

I suppose I could convert a spare AM tube receiver to be a BC band
transmitter but I don't really want to cannibalize one.

Anyway, what do people recommend?

Many thanks for all replies. Feel free to email me directly or, of
course, reply to the group.
Cheers,
Roger

"Reclaim, repair, refurbish, rebuild, reuse, recycle"
Anti-spam... Reply to: analogdino "at" rogers "dot" com
Scott Irvine
2006-08-02 04:25:15 UTC
Post by Engineer
Hi, Vacuumlanders.
I've seen this topic before but can't recall the outcome... Anyway, I'm
looking for a 100 mW (+/-) broadcast band AM transmitter kit so that I
can play my OTR CD's through my restored old time radios - from an
antenna in, not just jumpering the audio and faking it.
I have found the Ramsey Kits, in particular models AM1C (US$34.95) and
AM25 (US#99.95.) How good are they?
I also recall another brand that may have the numbers "3000" in the
name, but I can't be sure. IIRC, it seemed to get rave reviews.
I suppose I could convert a spare AM tube receiver to be a BC band
transmitter but I don't really want to cannibalize one.
Anyway, what do people recommend?
Many thanks for all replies. Feel free to email me directly or, of
course, reply to the group.
Cheers,
Roger
"Reclaim, repair, refurbish, rebuild, reuse, recycle"
Anti-spam... Reply to: analogdino "at" rogers "dot" com
I had an Am 1 tube transmitter kit from Antique Radio Supply that was
pretty simple and worked well. www.tubesandmore.com Part# K-488

Scott Irvine
Shawn K
2006-08-02 04:56:16 UTC
You are referring to the AMT3000, I don't have one of these yet, but it
is on my list of items to acquire.

www.sstran.com
Post by Engineer
I also recall another brand that may have the numbers "3000" in the
name, but I can't be sure. IIRC, it seemed to get rave reviews.
--
Shawn K
www.thisoldradio.com
Mikael Carlsson
2006-08-02 05:03:29 UTC
You are referring to the AMT3000 that can be found at http://www.sstran.com/

Mikael
Paul Dietenberger
2006-08-02 05:13:49 UTC
Post by Engineer
I've seen this topic before but can't recall the outcome... Anyway, I'm
looking for a 100 mW (+/-) broadcast band AM transmitter kit
Only 800 ways to skin this cat. Here are two more.

If you don't mind running on batteries or building your own power supply,
and can tolerate running on 1610kc, look for one of these Wild Planet Radio
DJ Studio toys. It's cheap and not a kit so you don't have to build it. They
aren't made any more but can sometimes be found on eBay. When they were new
they cost $20. Example:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190015826381

Syl designed this nice little transmitter (I *think* this is the most recent
ske)

http://oldradioz.com/schematics/AM_Transmitter_6BM8.pdf

These are the only two I've used, I'm satisfied with both and paid next to
nothing for either (the parts for the one I built from Syl's design were in
my junkbox.) If you don't want to use a 6BM8 it will work with any medium-mu
triode (a la 6J5) and power pentode (a la 6V6.)

Good luck.
paul
--
Posted via a free Usenet account from http://www.teranews.com
Paul Sherwin
2006-08-02 13:44:01 UTC
Post by Paul Dietenberger
If you don't mind running on batteries or building your own power supply,
and can tolerate running on 1610kc, look for one of these Wild Planet Radio
DJ Studio toys. It's cheap and not a kit so you don't have to build it. They
aren't made any more but can sometimes be found on eBay. When they were new
they cost $20.
You can shift the TX frequency down somewhat by changing the crystal. I
had to do this because most Euro radios won't tune that high.

There's lots of stuff on the net which lets you make the most of the
WPRDJ, e.g.
http://www.geocities.com/raiu_harrison/mwa/tech/circuits/wprdj.html
http://home.att.net/~weatheradio/wprdj.htm
http://part15.us/book/print/691

I've had some hum problems with mine, but apart from that it works well.

HTH, Paul
robert casey
2006-08-02 18:14:04 UTC
Post by Paul Sherwin
I've had some hum problems with mine, but apart from that it works well.
Inserting a few millihenry chokes on the power supply leads and on the
audio feed I found will help get rid of hum. This blocks the
transmitter's RF energy from getting into power supply rectifier diodes
in both the WPRDJ supply and the supplies running the audio source.
Thus getting rid of switched at 60 or 120Hz RF paths.
Carl WA1KPD
2006-08-05 13:00:22 UTC
I have one that I have never used

$25 and I will ship it anywhere in the US
--
Carl
WA1KPD
Visit My Boatanchor Collection at
http://home.comcast.net/~chnord/wa1kpd.html
Post by Paul Sherwin
Post by Paul Dietenberger
If you don't mind running on batteries or building your own power supply,
and can tolerate running on 1610kc, look for one of these Wild Planet Radio
DJ Studio toys. It's cheap and not a kit so you don't have to build it. They
aren't made any more but can sometimes be found on eBay. When they were new
they cost $20.
You can shift the TX frequency down somewhat by changing the crystal. I
had to do this because most Euro radios won't tune that high.
There's lots of stuff on the net which lets you make the most of the
WPRDJ, e.g.
http://www.geocities.com/raiu_harrison/mwa/tech/circuits/wprdj.html
http://home.att.net/~weatheradio/wprdj.htm
http://part15.us/book/print/691
I've had some hum problems with mine, but apart from that it works well.
HTH, Paul
Ken G.
2006-08-05 16:24:45 UTC
On the Radio DJ transmitter ... take it apart and cut the silly sound
effects out of circuit and remove all LED lights it will run for months
on a set of batterys and no hum . Other things in my house were causing
hum so i eliminated those and its worked very well .
The SStran is however the best you can get .
John Goller, k9uwa
2006-08-02 23:56:41 UTC
Post by Paul Dietenberger
Only 800 ways to skin this cat. Here are two more.
I'll throw out one more method... All of us have had extra.. Signal
Generators... or if you don't have an extra.. at the next radio meet
you can get one for 10 bucks... Very Slight Mods needed to input your
CD Player or whatever in place of that 600 or 1000 cycle audio generator
thats in it... the better signal jenny's even have a jack on the front
for applying "External Modulation" ... insert plug and hook it to your
CD Player... turn knob to frequency you want to transmit on... add
length of plain wire to the output lead...

John k9uwa
TerryJ
2006-08-03 00:18:27 UTC
Post by John Goller, k9uwa
Post by Paul Dietenberger
Only 800 ways to skin this cat. Here are two more.
I'll throw out one more method... All of us have had extra.. Signal
Generators... or if you don't have an extra.. at the next radio meet
you can get one for 10 bucks... Very Slight Mods needed to input your
CD Player or whatever in place of that 600 or 1000 cycle audio generator
thats in it... the better signal jenny's even have a jack on the front
for applying "External Modulation" ... insert plug and hook it to your
CD Player... turn knob to frequency you want to transmit on... add
length of plain wire to the output lead...
John k9uwa
Only problem is most will modulate 30% or less and the signal is full of
harmonics... it does work though.
Engineer
2006-08-06 00:03:16 UTC
Post by Paul Dietenberger
Post by Engineer
I've seen this topic before but can't recall the outcome... Anyway, I'm
looking for a 100 mW (+/-) broadcast band AM transmitter kit
(snip)
Post by Paul Dietenberger
Syl designed this nice little transmitter (I *think* this is the most recent
ske)
http://oldradioz.com/schematics/AM_Transmitter_6BM8.pdf
(snip)

Paul, this looks good - many thanks. I am planning to brew up
something similar using an RF pentode osc. with plate modulation by a
small audio power tube, e.g. a 6K6. I may just build this one, but
using two tubes as my 6BM8's are being saved for tube HI Fi !
Cheers.
Roger
PS. I have ordered an SMT3000 anyway as a reference.
Engineer
2006-08-06 00:08:18 UTC
Post by Paul Dietenberger
Post by Engineer
I've seen this topic before but can't recall the outcome... Anyway, I'm
looking for a 100 mW (+/-) broadcast band AM transmitter kit
(snip)
Post by Paul Dietenberger
Syl designed this nice little transmitter (I *think* this is the most recent
ske)
http://oldradioz.com/schematics/AM_Transmitter_6BM8.pdf
(snip)

Paul, this looks good - many thanks. I am planning to brew up
something similar using an RF pentode osc. with plate modulation by a
small audio power tube, e.g. a 6K6. I may just build this one, but
using two tubes as my 6BM8's are being saved for tube HI Fi !
Cheers.
Roger
PS. I have ordered an AMT3000 anyway, as a reference.

Sofa Slug
2006-08-02 07:09:11 UTC
Post by Engineer
Hi, Vacuumlanders.
I've seen this topic before but can't recall the outcome... Anyway, I'm
looking for a 100 mW (+/-) broadcast band AM transmitter kit so that I
can play my OTR CD's through my restored old time radios - from an
antenna in, not just jumpering the audio and faking it.
I have found the Ramsey Kits, in particular models AM1C (US$34.95) and
AM25 (US#99.95.) How good are they?
I also recall another brand that may have the numbers "3000" in the
name, but I can't be sure. IIRC, it seemed to get rave reviews.
I suppose I could convert a spare AM tube receiver to be a BC band
transmitter but I don't really want to cannibalize one.
Anyway, what do people recommend?
Many thanks for all replies. Feel free to email me directly or, of
course, reply to the group.
Cheers,
Roger
"Reclaim, repair, refurbish, rebuild, reuse, recycle"
Anti-spam... Reply to: analogdino "at" rogers "dot" com
It's my understanding that the cheaper Ramsey kit is not so hot. If you
don't want to spend a lot, I've heard good things about the Vectronics:

http://www.vectronics.com/products.php?prodid=VEC-1290K

The manual is here:

http://www.wb0w.com/vectronics/kits/pdf/vec1290k.pdf

If money is not an issue, I'd go for the SSTRAN AMT3000 already mentioned.
Lyndell Scott
2006-08-02 12:25:14 UTC
As a followup to what Paul said, I use a 6V DC walwart to power my Radio DJ
without any hum or noise.
--
Lyndell Scott
Audio Antiques
http://geocities.com/***@flash.net
Steven
2006-08-02 12:32:55 UTC
Post by Lyndell Scott
As a followup to what Paul said, I use a 6V DC walwart to power my Radio DJ
without any hum or noise.
--
Lyndell Scott
Audio Antiques
Somebody pull up the Goople search results on the Wild Planet Wireless
DJ and other mods for Lyndell? That microphone was really something it
seems in early runs and there not much reason one like it can't be made
to take input from a mixing board or server and made into a part 15
dream. I myself live too close to a radio station where I am quite
familiar after so many years, so I don't even try and FM is too crowded
to not mangle someone's reception.
Bill Turner
2006-08-02 13:57:27 UTC
HERE IS A SIMPLE WAY OF CREATING YOUR OWN BROADCASTER WITH A MINIMUM OF
TROUBLE. FIRST YOU NEED TWO AC/DC TABLE RADIOS. ON ONE YOU SWAP THE
12SA7 AND THE 50L6. THERE ARE A COUPLE WIRES THAT NEED TO BE CHANGED.
THIS GIVES YOU A "HIGH POWER" TRANSMITTER. WIRE THE RF SECTION OF THE
TUNING CAPACITOR IN PARALLEL WITH THE OSC., THIS ALLOWS YOU TO SET THE
FREQUENCY LOWER IN THE BAND. CONNECT THE PRIMARY OF THE OUTPUT
TRANSFORMER IN SERIES WITH THE PLATE OF THE 50L6. THIS IS NOW THE
MODULATION TRANSFORMER. CONNECT THE SEC. OF THIS TRANSFORMER TO THE
SEC. OF THE OTHER RADIO. DISCONNECT THE AUDIO LEAD FROM THE VOLUME
CONTROL OF THE SECOND RADIO AND CONNECT THE AUDIO SOURCE TO THAT POINT.
TWO TABLE RADIOS, EVEN IF YOU HAVE TO BUY THEM IS VERY CHEAP, MOST OF US
HAVE A COUPLE ON THE UPPER SHELF. THIS IS THE ARRANGEMENT USED WHEN
HILLBILLY POLE CLIMBERS PLAYED THEIR RADIO AS LOAD AS IT WOULD GO WHEN I
WAS AT THE SIGNAL SCHOOL.


CHECK MY WEBSITE: www.dialcover.com
Bill Turner, excuse caps, short answers, stroke.
Business SASE, each order a copy of The Pocket Resource Guide.
Gary Tayman
2006-08-02 18:08:15 UTC
It appears you're referring to the SSTRAN AMT-3000 transmitter, as already
mentioned by several others here.

I have one myself and I highly recommend it for AM radio listening. You can
adjust the input gain, modulation level, and amount of compression to make a
signal that's pretty darn close to that of commercial broadcast. In fact
the biggest difference is that the AMT-3000 has a wide-open frequency
response up to 20kHz, whereas the normal AM channel allocation calls for a
5kHz limit. So it's actually better -- except for the fact that most radio
receivers filter out the highs anyway, so it doesn't matter.

I personally use mine to listen to OTR on my Atwater Kent when working in
the shop. I also use it to tune and test AM radios.
--
Gary E. Tayman/Tayman Electrical
Sound Solutions For Classic Cars
http://www.taymanelectrical.com
Post by Engineer
Hi, Vacuumlanders.
I've seen this topic before but can't recall the outcome... Anyway, I'm
looking for a 100 mW (+/-) broadcast band AM transmitter kit so that I
can play my OTR CD's through my restored old time radios - from an
antenna in, not just jumpering the audio and faking it.
I have found the Ramsey Kits, in particular models AM1C (US$34.95) and
AM25 (US#99.95.) How good are they?
I also recall another brand that may have the numbers "3000" in the
name, but I can't be sure. IIRC, it seemed to get rave reviews.
I suppose I could convert a spare AM tube receiver to be a BC band
transmitter but I don't really want to cannibalize one.
Anyway, what do people recommend?
Many thanks for all replies. Feel free to email me directly or, of
course, reply to the group.
Cheers,
Roger
"Reclaim, repair, refurbish, rebuild, reuse, recycle"
Anti-spam... Reply to: analogdino "at" rogers "dot" com
Bill Sheppard
2006-08-02 20:42:04 UTC
...the AMT-3000 has a wide-open
frequency response up to 20kHz,
whereas the normal AM channel
allocation calls for a 5kHz limit. So it's
actually better -- except for the fact that
most radio receivers filter out the highs
anyway, so it doesn't matter.
Except for one thing - the power that goes into radiating the sidebands
above 5khz is wasted if it's never heard in the receiver. It's basically
the same reason you don't use a hi-fi amp to modulate a ham rig. You
want to limit the audio bandwidth (in this case to speech) so it all
goes into effective radiated power instead of "splattering" the carrier
out excessively, wasting power.
Bill(oc)
Paul Dietenberger
2006-08-02 22:12:31 UTC
Post by Bill Sheppard
...the AMT-3000 has a wide-open
frequency response up to 20kHz,
Except for one thing - the power that goes into radiating the sidebands
above 5khz is wasted if it's never heard in the receiver.
IIRC the wide frequency response isn't the default for that unit, you have
to set a jumper to make it respond to anything over 5kHz. It's to take
advantage of "hi-fi" and adjustable-selectivity '30s AM radios.

-p
--
Posted via a free Usenet account from http://www.teranews.com
Steven
2006-08-02 22:21:02 UTC
Post by Paul Dietenberger
Post by Bill Sheppard
...the AMT-3000 has a wide-open
frequency response up to 20kHz,
Except for one thing - the power that goes into radiating the sidebands
above 5khz is wasted if it's never heard in the receiver.
IIRC the wide frequency response isn't the default for that unit, you have
to set a jumper to make it respond to anything over 5kHz. It's to take
advantage of "hi-fi" and adjustable-selectivity '30s AM radios.
-p
--
Posted via a free Usenet account from http://www.teranews.com
I was getting 12-16 kHz from KBOI in the good old daze, platform motion
or not, on an SRF-42 AMAX Walkman, or at least it seems, and KBSU was
nice but by then they had clamped down on the 10 kHz thing.
John Byrns
2006-08-03 02:37:48 UTC
Post by Paul Dietenberger
Post by Bill Sheppard
...the AMT-3000 has a wide-open
frequency response up to 20kHz,
Except for one thing - the power that goes into radiating the sidebands
above 5khz is wasted if it's never heard in the receiver.
IIRC the wide frequency response isn't the default for that unit, you have
to set a jumper to make it respond to anything over 5kHz. It's to take
advantage of "hi-fi" and adjustable-selectivity '30s AM radios.
There is no jumper in the AMT-3000 that restricts the frequency response,
unless there is a mark 2 model that includes such a jumper. I think you
are being confused by the jumper that inserts a pre-emphasis circuit like
is used on FM and modern day AM. If you want the AMT-3000 to operate
properly with "hi-fi" and adjustable-selectivity '30s AM radios you need
to operate it with the pre-emphasis disabled, or in what you would call
the narrow frequency response mode.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/
Paul Dietenberger
2006-08-03 03:41:11 UTC
Post by John Byrns
There is no jumper in the AMT-3000 that restricts the frequency response,
unless there is a mark 2 model that includes such a jumper. I think you
are being confused by the jumper that inserts a pre-emphasis circuit like
is used on FM and modern day AM. If you want the AMT-3000 to operate
properly with "hi-fi" and adjustable-selectivity '30s AM radios you need
to operate it with the pre-emphasis disabled, or in what you would call
the narrow frequency response mode.
Oops, yes, you are correct. My fault. Thanks for clarifying.

-paul
--
Posted via a free Usenet account from http://www.teranews.com