Using a Signal Generator for an "In Home" radio transmitter

[Chuck]

On Mon, 7 Jan 2019 12:57:48 -0800 (PST), jurb6006@gmail.com wrote:

You're off by a factor of ten. You want up to 1,650 KHz. Actually it is so easy to build an oscillator like that and easy to amplitude modulate that might be a better option. Well unless you have nothing better to do with the generator.

Crystal controlled would be better because drift is not good. But then if you just leave it on all the time it will settle in and be stable enough.

Another thing is to keep the power down, you don't need problems with the FCC. They got a SWAT team, I shit you not. I am not sure what you can get away with, maybe 100mW or 500, something like that. A quick Google didn't yield a straight answer but I would say just make sure the signal doesn't leave the house.

I know it is absolutely illegal to use any of the FM band, that this when they come and treat you like you're running a meth lab. However there is so much noise on AM that they might never even suspect. You might be better running the "transmitting antenna" through wires to the desired locations. I fit leaves the house, even on your own property that might mean trouble. And we are talking feds here, that means your miracle worker lawyer is no good.

I used to live in a city with 50,000 residents in the southern U.S..
There was, and probably still is, a pirate station in the educational
FM band. It has been on the air for years and it doesn't interfere
with local FM signals. I have sinced moved to a town of 20,000 people
in southern MN. Someone started a pirate station playing Tejano music
24 hours a day. Unfortunately their frequency was at 90.3 MHz and the
signal bled over onto the local MPR signal at 90.1. I complained to
the FCC and within 3 weeks they shut the station down. So it appears
that the FCC is more aggressive when the station impinges on
legitimate signals.

 

[Fox's Mercantile]

On 1/8/19 11:46 AM, John-Del wrote:

On Tuesday, January 8, 2019 at 11:09:38 AM UTC-5, Fox's Mercantile wrote:
On 1/8/19 9:19 AM, amdx wrote:
into my FM transmitter

And how is that supposed to work with a bunch of AM radios?



You feed the headphone jack of the FM radio into an AM XMTR...

Sheesh Jeff!!

Heh, I keep seeing people totally oblivious to the requirement
of an AM transmitter for BCB AM radios.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

[Dave Platt]

In article <2jo93e5o60lea4jfiqg5vld5l3ooljg2ub@4ax.com>,
Chuck <ch@dejanews.net> wrote:

. Someone started a pirate station playing Tejano music
24 hours a day. Unfortunately their frequency was at 90.3 MHz and the
signal bled over onto the local MPR signal at 90.1. I complained to
the FCC and within 3 weeks they shut the station down. So it appears
that the FCC is more aggressive when the station impinges on
legitimate signals.

"Harmful interference" vs. "unauthorized operation". Both can come
with big fines... but, yes, the FCC is somewhat more likely to react
when faced with a situation where a legitimate licensed broadcaster is
being interfered with. (Commercial licensees have paid $$ for their
licenses, and don't like losing market-share/coverage to pirate
transmitters).

 

[amdx]

On 1/8/2019 12:22 PM, Fox's Mercantile wrote:

On 1/8/19 11:46 AM, John-Del wrote:
On Tuesday, January 8, 2019 at 11:09:38 AM UTC-5, Fox's Mercantile wrote:
On 1/8/19 9:19 AM, amdx wrote:
into my FM transmitter

And how is that supposed to work with a bunch of AM radios?



You feed the headphone jack of the FM radio into an AM XMTR...

Sheesh Jeff!!



Heh, I keep seeing people totally oblivious to the requirement
of an AM transmitter for BCB AM radios.

I was oblivious to your requirement, you made that clear. I just
wanted to let people know what I do, and to make them aware of the old
radio programs available over the internet. Listening to Dragnet as I
write, on an FM radio!

Mikek

btw, has anyone tried a class E amplifier as an AM transmitter?
Base/gate drive is transmit frequency, B+ is the audio.
I'll google it.

 

[Fox's Mercantile]

On 1/8/19 6:10 PM, amdx wrote:

btw, has anyone tried a class E amplifier as an AM transmitter?
 Base/gate drive is transmit frequency, B+ is the audio.
I'll google it.

On of the "Impress kids" kit is an AM transmitter.
It's 1 MHz TTL crystal oscillator.
The Vcc is fed through an audio transformer.

Pretty slick, an AM transmitter with only 2 parts.


--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

[amdx]

On 1/8/2019 6:49 PM, Fox's Mercantile wrote:

On 1/8/19 6:10 PM, amdx wrote:
btw, has anyone tried a class E amplifier as an AM transmitter?
  Base/gate drive is transmit frequency, B+ is the audio.
I'll google it.

On of the "Impress kids" kit is an AM transmitter.
It's 1 MHz TTL crystal oscillator.
The Vcc is fed through an audio transformer.

Pretty slick, an AM transmitter with only 2 parts.

Ya, I found some, you do need some DC bias on the secondary of the
transformer.
See page 21, 2nd page from bottom.>
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=18&ved=2ahUKEwjeiPbN09_fAhVyg-AKHVAeDFEQFjARegQIABAC&url=https%3A%2F%2Fwww.crarc.ampr.org%2Fuploads%2FMain%2FArchives%2FJuly%2520Class-E%2520Transmitters.pdf&usg=AOvVaw2RezBtb1JfwKR236TgSS4v

Here's an AM transmitter with 3 parts.
> https://www.youtube.com/watch?v=YNGs-IX_B2s

Mikek

 

Jeff Liebermann wrote: "Try 1650 KHz instead. Kilocycles died 50 years ago."


Any tech worth their salt understands both. They
express the same value.

 

[Fox's Mercantile]

On 1/8/19 10:02 PM, thekmanrocks@gmail.com wrote:

Jeff Liebermann wrote: "Try 1650 KHz instead. Kilocycles died 50 years ago."


Any tech worth their salt understands both. They
express the same value.

And only the humor impaired see the need to point that out.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

[Jeff Liebermann]

On Tue, 8 Jan 2019 20:02:30 -0800 (PST), thekmanrocks@gmail.com wrote:

Jeff Liebermann wrote: "Try 1650 KHz instead. Kilocycles died 50 years ago."
Any tech worth their salt understands both.

Bulk table salt sells for about $100 per metric ton. Methinks I'm
worth more than that.

>They express the same value.

Not the way they were originally written. Hz = cycles/second.
However, the original comment was "16,500 kc" which is just cycles. No
way to know if that's cycles/sec, cycles/minute, cycles/fortnight, or
just counting waveform cycles. If he had written "cps", which means
cycles/second, I might agree, but not kc.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Mike Coon]

In article <jn9b3e5cmq5tfl8n1ou31nk9u9gc45ejgd@4ax.com>,
jeffl@cruzio.com says...

On Tue, 8 Jan 2019 20:02:30 -0800 (PST), thekmanrocks@gmail.com wrote:

Jeff Liebermann wrote: "Try 1650 KHz instead. Kilocycles died 50 years ago."
Any tech worth their salt understands both.

Bulk table salt sells for about $100 per metric ton. Methinks I'm
worth more than that.

They express the same value.

Not the way they were originally written. Hz = cycles/second.
However, the original comment was "16,500 kc" which is just cycles. No
way to know if that's cycles/sec, cycles/minute, cycles/fortnight, or
just counting waveform cycles. If he had written "cps", which means
cycles/second, I might agree, but not kc.

But at least it was "k" for 1000x, not "K" for 1024x ...

Mike.

 

On Tuesday, January 8, 2019 at 11:02:34 PM UTC-5, thekma...@gmail.com wrote:

Jeff Liebermann wrote: "Try 1650 KHz instead. Kilocycles died 50 years ago."


Any tech worth their salt understands both. They
express the same value.

OK smartypants, what is -40 Fahrenheit in Centigrade ?

 

On Tue, 8 Jan 2019 10:37:40 -0800, dplatt@coop.radagast.org (Dave Platt)
wrote:

In article <2jo93e5o60lea4jfiqg5vld5l3ooljg2ub@4ax.com>,
Chuck <ch@dejanews.net> wrote:

. Someone started a pirate station playing Tejano music
24 hours a day. Unfortunately their frequency was at 90.3 MHz and the
signal bled over onto the local MPR signal at 90.1. I complained to
the FCC and within 3 weeks they shut the station down. So it appears
that the FCC is more aggressive when the station impinges on
legitimate signals.

"Harmful interference" vs. "unauthorized operation". Both can come
with big fines... but, yes, the FCC is somewhat more likely to react
when faced with a situation where a legitimate licensed broadcaster is
being interfered with. (Commercial licensees have paid $$ for their
licenses, and don't like losing market-share/coverage to pirate
transmitters).

Right now is probably the PERFECT time to operate a pirate station.
Since the government is shut down, the FCC is probably not doing much.
NO, I am not encouraging this, just commenting......

 

On Mon, 7 Jan 2019 14:55:43 -0600, Fox's Mercantile <jdangus@att.net>
wrote:

On 1/7/19 1:33 PM, tubeguy@myshop.com wrote:
Is it possible to use a Signal Generator for an "In Home" radio
transmitter?

Yeah, but it'll sound like crap.
Because most of those old generators will only do about
30% modulation. And they're not exactly set up for any
kind of modulation bandwidth.

There's the SSTRAN 3000 which I use.
http://www.sstran.com/

I watched a youtube video about this transmitter (actually SSTRAN 5000).
I thought this was a good option. I clicked on the URL you posted and it
appears they are OUT OF BUSINESS. Their website says something to the
extent "No new orders after November xx 2017, and new customers who
already paid, will be issued a refund.......

Another option is the Talking House transmitter.
https://www.ebay.com/itm/223314565635

This one is being considered........

Or, you can roll your own.
https://antiqueradio.org/transmitter.htm

Obtaining the inductors (coils) is that hard part for ANY transmitters.
I recall haveing a tough time getting them in the late 1960s. I'm sure
it's 1000 times harder now. I did get the coils and did build what was
called a "Phono Transmitter" in the late 60's. It worked well. Then I
took it one step further. I replaced the tube with the horizontal output
tube from a TV, and upped the high voltage to around 800V. (The power
supply was on a separate chassis).

At that time, I was living in a big city. Using a car radio antenna
mounted about 30 ft up on a tree, I put this thing on the air. I never
expected the results I got. Several neighbors said their AM radios could
not get any stations, except mine. A friend who lives in the suburbs
about 15 miles away, said he got my station, clear as a bell.

I got carried away and had it running about 12 hours a day. Had friends
act as disk jockeys and we played a lot of the songs that were banned on
the regular radio stations. We got a regular studio sound mixer and
connected 3 turntables, an 8track and a reel to reel tape player, plus a
few microphones. A lot of people loved the station, and wanted to know
the location. But we never told that to anyone, knowing this was a
pirate station and not legal.

One day a fancy car with all kinds of weird antennas on it began
circling my block. I shut off the transmitter immediately. I am very
sure it was the FCC, but that tree antenna was well hidden. I planned to
move it to another friend's house, but we never did go back on the air.
I wish I still had that transmitter. If I did, I'd down power it back to
the original design.....

By the way, that thing taught me to respect electricity. I was probably
17 years old. I was tweaking the transmitter when I grabbed the plastic
knob on the tuning cap, but my knuckle touched the cap itself, which was
live 800VDC. I had a grounded microphone in my other hand. I was sitting
on a heavy oak chair. Both myself and the chair were thrown about 12
feet away. The guy who was with me, said I walked around in a daze for a
half hour and kept drinking water every few seconds. All I recall, is
what looked like a bolt of lightning, when it hit me, and laying on the
floor 12 ft from my bench. He said the microphone hit him in the head
when I "launched". I sort of recall shutting off the switch that powered
my whole bench, right after. That was one scary shock. The worse I ever
got.

I did encapsule that tuning cap in a box after that, and modified that
cap as well, because I used to get arcing between the plates. The
original one was a common 365pf AM radio tuning cap. I remember buying a
costly ceramic cap to replace it. Then building a shield around it to
avoid any chance of touching it.

When I look back, that whole thing was a lot of fun, aside from that
shock. A lot of people were saddened when we went off the air.

 

On Mon, 07 Jan 2019 16:00:35 -0500, Pat <forums@greensdomain.com> wrote:

On Mon, 07 Jan 2019 13:33:15 -0600, tubeguy@myshop.com wrote:

Is it possible to use a Signal Generator for an "In Home" radio
transmitter?

I would like to make a small in the house AM radio transmitter, so I can
listen to my own music collection of MP3 music on my antique radios. I
know I can buy a transmitter for this use, but I am wondering if I can
use what I already have.

For example, I have an Eico 315 Signal Generator. It has an internal
400cps audio generator, but it also has the capability of inserting
another audio signal.

So, can I just take a MP3 player and run that into the signal generator,
and connect the sig gen to a piece of long wire strung inside my home to
transmit the signal? Is there enough power to transmit inside my own
home? I'd probably string 10 to 20 ft of wire along the edge of the
ceiling, or across curtain rods from window to window.

Of course I'd set the sig gen to an MW AM radio frequency, such as
16,500 kc.

Yes. Your signal generator can be used for that. I doubt you need
more than a foot or two of wire for the antenna. The frequency you
mentioned, however, isn't MW. It's short wave (which may possibly be
received on your antique radios in addition to MW). Perhaps it was
just a typo on your part, but the AM broadcast band is from 540 to
1700 kHz (formerly referred to as kc). 1600 to 1700 wasn't part of
the band until after any radio called antique was sold, so 540 to 1600
is what you want to use.

Have Fun,
Pat

Thanks to all who replied. I am considering geting one of them ebay mini
transmitters, but this is more to see if I can do it with the signal
gen. And I have 3 of them to try. I think my Eico 315 is the most
suitable though and is my best one.

Yea, I was not thinking when I typed that band number. I was thinking
1650 khz though. (just to avoid other stations from interfering). I have
never known any AM stations to exist above 1600. I sort of thought all
radios went to 1700, but I guess I was wrong.

Just curious, in what year did they add 1600 to 1700 to the AM band?
It does seem to me that a few times I have sent a signal to one of these
antique radios and gone above 1600 though, while aligning them. But I
suppose it depends on the radio design and how far the tuning cap can
go.

For sound quality and for stereo, a FM transmitter would be better, but
most of my antique radios are only AM band.

I am not too worried about the FCC coming to "get me". First off, I live
in a all metal home. Metal siding and roof. To use my cellphone I have
to go outside. Secondly, I live on a farm, and the nearest neighbor is a
mile away. So even if it does leak outside a little, only the deer and
pesky raccoons who carry pocket radios will pick up my signal. Of course
I will take a walk with a pocket radio or use my car radio just to see
if it is going beyond my home, and how far.

Interestingly enough, after I posted this, I went to youtube and typed
in a few words to search for this. I found that I am not the first
person to attempt this. Some guy did it. He found that running a MP3
player right into the signal generator had very weak audio. He then ran
the MP3 player into a stereo amp, and connected the amp's output to the
signal gen. Doing that, did make a strong signal, but it was rather
distorted. However, he connected the 8 ohm speaker output to the signal
gen. That alone seems like an overload. I'd be more inclined to use a
preamp between the signal gen and the MP3 player. Or use the "tape out"
jack from on a stereo amp or receiver. (which is preamp output).

I'll play with it, and see what happens, and post the results, unless
the FCC hauls me away and locks me up in some prison in Russia.
(Which means I better not play any Russian music over the air).

 

On Tue, 8 Jan 2019 18:10:49 -0600, amdx <nojunk@knology.net> wrote:

On 1/8/2019 12:22 PM, Fox's Mercantile wrote:
On 1/8/19 11:46 AM, John-Del wrote:
On Tuesday, January 8, 2019 at 11:09:38 AM UTC-5, Fox's Mercantile wrote:
On 1/8/19 9:19 AM, amdx wrote:
into my FM transmitter

And how is that supposed to work with a bunch of AM radios?



You feed the headphone jack of the FM radio into an AM XMTR...

Sheesh Jeff!!



Heh, I keep seeing people totally oblivious to the requirement
of an AM transmitter for BCB AM radios.


I was oblivious to your requirement, you made that clear. I just
wanted to let people know what I do, and to make them aware of the old
radio programs available over the internet. Listening to Dragnet as I
write, on an FM radio!

Aside from not being AM, I plan to give that link a listen. Sounds like
fun listening to those old radio shows. (By the way, those shows were
probably all broadcast on AM. FM did not exist at that time).

Mikek

btw, has anyone tried a class E amplifier as an AM transmitter?
Base/gate drive is transmit frequency, B+ is the audio.
I'll google it.

 

[Fox's Mercantile]

On 1/9/19 8:03 PM, tubeguy@myshop.com wrote:

Aside from not being AM, I plan to give that link a listen. Sounds like
fun listening to those old radio shows. (By the way, those shows were
probably all broadcast on AM. FM did not exist at that time).

FM radio was assigned the 42 to 50 MHz band of the spectrum in 1940.
But then WWII happened. After the war, on June 27, 1945 the FCC made
its decision final and allocated one hundred FM channels from 88–108
MHz.

The "Golden Age of American radio", period lasting roughly from 1930
through the 1940s, However he last network radio dramas to originate
during American radio′s "Golden Age", Suspense and Yours Truly, Johnny
Dollar, ended on September 30, 1962.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

[Fox's Mercantile]

On 1/9/19 8:03 PM, tubeguy@myshop.com wrote:
> I have never known any AM stations to exist above 1600.

It is currently 530-1700 KHz.
Originally, in 1923, it was 540-1340 KHz.


--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

[pfjw@aol.com]

On Wednesday, January 9, 2019 at 9:31:42 PM UTC-5, jurb...@gmail.com wrote:

On Tuesday, January 8, 2019 at 11:02:34 PM UTC-5, thekma...@gmail.com wrote:
Jeff Liebermann wrote: "Try 1650 KHz instead. Kilocycles died 50 years ago."


Any tech worth their salt understands both. They
express the same value.

OK smartypants, what is -40 Fahrenheit in Centigrade ?

The same. I am bi-temperate having lived under metric and non-metric systems.

Peter Wieck
Melrose Park, PA

 

[pfjw@aol.com]

On Wednesday, January 9, 2019 at 9:48:36 PM UTC-5, Fox's Mercantile wrote:

On 1/9/19 8:03 PM, tubeguy@myshop.com wrote:
I have never known any AM stations to exist above 1600.

It is currently 530-1700 KHz.
Originally, in 1923, it was 540-1340 KHz.


--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I have a 1930s-vintage Coronado chairside that looks like this:

http://antiqueradios.com/gallery/main.php?g2_itemId=29062 That calls itself a dual band radio, being AM & Police/Aircraft. It is a single-band radio with the AM bandwidth expanded.

The dial goes from 530 to 1790. Police band back in the day was 1714. I have not been able to pin down Aircraft, but I expect somewhere below 1790.

The radio is also unusual in that it had an acorn bias-cell - now replaced with a 1.5V AAA. Plays nicely.

Peter Wieck
Melrose Park, PA

 

[pfjw@aol.com]

I keep a 3000 and a 5000, and for years I distributed them at Kutztown for Phil Bolyn, the developer. In my opinion, they are the ne plus ultra of amateur hobby AM transmitters. I will state for the record, that most (not all) of the stuff you will find on eBay is either junk, too powereful, or too weak to be useful.

http://www.talkinghouse.com/

These are often sold at Kutzown, already adapted for a stereo input. They have the virtue of being frequency agile, and rather simple to operate, but as-furnished, they do not allow for much signal processing. Their more expensive version does allow for such signal processing, as well as a considerably extended dynamic range. It is all in accordance with what you wish to achieve. Considering that back in the day, those transmitters were capable of broadcasting across the full audio band, but given the need to carry, and not step on adjacent frequencies, they pretty much limited the bandwidth to ~100 - ~5000 hz, often considerably less both ways. Whereas the receiving radios were capable of getting the entire audio bandwidth.

Note that the SSTRAN is rated at 20-20K, and after using it, other transmitters will sound quite thin.

Peter Wieck
Melrose Park, PA