Home AM transmitter

Go down

Home AM transmitter

Post by Brig on Thu Nov 24, 2011 4:24 pm

I'ver built three AM transmitters from AA5 receivers. Each varied in circuitry slightly, although all were of the converter plate modulation type. I know that this design is frowned upon by radio people more experienced than I am in transmitting equipment, but, for me, the style is ideal. My latest attempt was very recently, using directions supplied by a George Gonzales back in 1997 in the R&P forum. I used an AA5 receiver I had purchased cheaply many years ago, and which I had threatened to junk several times.

The results, in my opinion, have been outstanding. Like the others I made it covers my entire house, plus the back yard. The tonal quality is superb, I couldn't ask for it to be better. My audio sources are a CD player and the headphone jack of a portable FM receiver. (I'm lucky in that I receive an FM station that plays "my" kind of music all day.)

My main question, for which I hope someone can help, has to do with the antenna. The unit will not broadcast unless it is connected to my outdoor long (about 35 feet) wire antenna. The other two units I've put together put out a loud and clear signal with only three or four feet of wire as an antenna.

Whatever, I'm very happy with this device and would like to converse with others who have favorful experience with this type of home transmitter. --Tom S.




Brig
Member
Member

Number of posts : 65
Registration date : 2011-08-18

Back to top Go down

home brew XMiter

Post by pawpawhunt on Thu Dec 01, 2011 8:09 pm

Hey there!! I built one out of an old high FI amp that had a pair of 6L6's and the power supplyed about 700 volts to them, I only used one 6L6 and had to scrap it because it shut down my TV and sattlite system,
???

pawpawhunt
Member
Member

Number of posts : 21
Registration date : 2011-11-10

Back to top Go down

Re: Home AM transmitter

Post by Brig on Sat Dec 10, 2011 6:57 pm

My unit will broadcast on a short (ca. six feet) antenna, I have discovered, if I set it and the various receivers to a different frequency. At about 1000 kc the long wire antenna signal is received at about the same frequency on all the receivers I use throughout the house; at about 1300 kc using the short antenna, the signal is received between 1150 and 1400 kc, depending on which receiver I am tuned to. In both cases, the reception is outstanding. However, I cannot explain the antenna length/reception frequency difference.

Brig
Member
Member

Number of posts : 65
Registration date : 2011-08-18

Back to top Go down

Re: Home AM transmitter

Post by Doug Burskey on Sun Dec 11, 2011 9:26 pm

There were wireless record players made in the 1940's so you can play records through your radio.They were nothing but a small low powered AM transmitter.Antique Electronic Supply sells (or did sell ) a one tube wireless transmiter kit K-488 for $39.95.Circut was based of a Zenith wireless record player.I built one, works reasonably well but haven't used it much.

Doug Burskey
Member
Member

Number of posts : 226
Age : 59
Registration date : 2011-06-22

Back to top Go down

Re: Home AM transmitter

Post by Brig on Mon Feb 06, 2012 6:41 pm

pawpawhunt wrote:Hey there!! I built one out of an old high FI amp that had a pair of 6L6's and the power supplyed about 700 volts to them, I only used one 6L6 and had to scrap it because it shut down my TV and sattlite system,
???

Because an amplifier would not have an oscillator section, I don't understand how the unit you constructed functioned as an AM transmitter. Do you mean that you added an audio input jack to the unit and plugged in a CD player and were able to listen to CD's through the amplifier and a speaker?

Brig
Member
Member

Number of posts : 65
Registration date : 2011-08-18

Back to top Go down

Re: Home AM transmitter

Post by big bill on Sun Feb 19, 2012 9:48 pm

It was confi,d as an RF amp following my low power tranx which would only play across the room! it had too much out band harmonics that it interfered with my TV & satatlite system. the tranx was a one tube (12cs6) lots better audio than 12be6.

big bill
New Member
New Member

Number of posts : 3
Registration date : 2011-11-10

Back to top Go down

Re: Home AM transmitter

Post by Motorola man on Fri Mar 09, 2012 11:25 pm

I'm getting ready to try the AA5 transmitter modification with a cheap, plastic GE clock radio. I've got to replace the electrolytics to get the radio playing first. Just wondering, do I need to stretch an antenna wire up the wall, or can I get away with making a coil inside the cabinet? My receiving radio will only be 15 feet away at most.
Dave
avatar
Motorola man
Member
Member

Number of posts : 375
Age : 42
Registration date : 2010-02-06

Back to top Go down

Re: Home AM transmitter

Post by Brig on Sat Mar 10, 2012 5:51 pm

Re your converting an AA5 receiver to a home AM transmitter, what circuit or design are you following? I can comment more easily about antenna needs if I know what the design is.

Brig
Member
Member

Number of posts : 65
Registration date : 2011-08-18

Back to top Go down

Re: Home AM transmitter

Post by Motorola man on Sat Mar 10, 2012 9:18 pm

I came across a youtube video by Bob W9RAN. This is the design that I'm planning on using, unless there's a better way of doing it with the same type of radio.
avatar
Motorola man
Member
Member

Number of posts : 375
Age : 42
Registration date : 2010-02-06

Back to top Go down

Re: Home AM transmitter

Post by Brig on Sun Mar 11, 2012 12:42 pm

Please see my post of Dec. 10 above.

You will not need a long wire going "up the wall." I have about 6-7 feet of ordinary 22 ga stranded hookup wire from the unit, under my workbench, and up to a parking place (using an alligator clip). This antenna transmits throughout my entire house, to two outbuildings, and about 90 feet north and south of my front outside.

I don't think a long wire coil mounted inside the cabinet will work very effectively, so I cannot recommend this.

As for antennas on the receivers you wish to broacast to, you won't need more than a foot or so of wire attached to the receiver's antenna terminal. If you plan to broadcast to a receiver with a built-in loop antenna, no other antenna will be necessary; in fact, extra antenna in this case can very well produce distorted reception due to overload.

Experimenting with various lengths of antenna, output volume, best frequencies, etc., will answer most questions and lead to a permanent arrangement for on-off usage.

I watched the YouTube video by Bob W9RAN. "His" design is the same one I found in an antiques radio online forum way back in the '90s. I also read all of the comments to this video. The ones that are negative are obviously based in ignorance, in never having actually constructed this simple yet very effective device.

If you get your unit working satisfactorily, I'd suggest you "install" it in your home or
shop as carefully as you'd install a good radio that you're proud to display and use, rather than simply keeping it on a cluttered workbench amidst a tangle of clip cords, the way many of these DIY devices are displayed on YouTube and other sites.

Let us know about your results.



Brig
Member
Member

Number of posts : 65
Registration date : 2011-08-18

Back to top Go down

Re: Home AM transmitter

Post by Motorola man on Sun Mar 11, 2012 1:23 pm

Thanks for the help. The transmitter will be displayed in my living room for use with my Zenith 8-S-463, which will sit about 10'-15' away in the same room. Since it will be in a very visible place, I don't want a long piece of wire strung across the room. I'll hopefully have it up & running this week, so I'll do a little experimentation & see what's going to work & look the best.
Dave
avatar
Motorola man
Member
Member

Number of posts : 375
Age : 42
Registration date : 2010-02-06

Back to top Go down

Re: Home AM transmitter

Post by Motorola man on Mon Mar 19, 2012 7:12 pm

I got the transmitter mod completed this evening & it works fairly well. With a 10'+ antenna just wadded up on the bench, I was able to get reception on a pocket transistor radio from about 7' away with decent sound. Tomorrow I'll try a little experimenting with the antenna.
Dave
avatar
Motorola man
Member
Member

Number of posts : 375
Age : 42
Registration date : 2010-02-06

Back to top Go down

Re: Home AM transmitter

Post by Motorola man on Wed Mar 21, 2012 10:29 am

Well here it is... my new transmitter. For what it is, it sounds pretty decent. I'll probably invest in an SSTran one of these days, but this will work for now.
Dave
avatar
Motorola man
Member
Member

Number of posts : 375
Age : 42
Registration date : 2010-02-06

Back to top Go down

Re: Home AM transmitter

Post by Bill Cahill on Tue May 14, 2013 3:30 am

Why is the picture gone? I wanted to see it.
Bill Cahill

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4582
Age : 67
Registration date : 2008-03-12

Back to top Go down

Re: Home AM transmitter

Post by Brig on Tue May 14, 2013 10:41 am

I had hoped to see it, too.

Brig
Member
Member

Number of posts : 65
Registration date : 2011-08-18

Back to top Go down

Re: Home AM transmitter

Post by Motorola man on Wed May 15, 2013 7:37 pm

I rearranged my photo bucket folders, so the picture got moved. Here it is again.

I've since invested in a talking house transmitter, which works much better.
avatar
Motorola man
Member
Member

Number of posts : 375
Age : 42
Registration date : 2010-02-06

Back to top Go down

Re: Home AM transmitter

Post by Bill Cahill on Wed May 15, 2013 8:28 pm

I kept, and, restored the chassis out of a 40's Motorla am oscilator.
The record changer was trashed with rotted, broken pot metal parts.
It's a two tube unit. It uses a 6J5 for rect., and, a 6SA7 ror oscilator.
I added a matching impedence transformer, and, put it in a cheap japanese spkr. box.
I can connect it to any good amplifier, and, get good transmission with fairly good bass response.
Has a smal power transformer .
I still have it, but, haven't used it in twenty years.
Did try it briefly last year, though, and, it still worked.

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4582
Age : 67
Registration date : 2008-03-12

Back to top Go down

Re: Home AM transmitter

Post by 276merc on Sun Sep 29, 2013 12:05 pm

I have about 20A to cover (not all mine) so I cranked up a bit more power by slightly modifying an old 160M ham mobile transmitter circuit from the 50's.

The VFO is a 6EA8 VFO/Buffer driving a 6AQ5. The audio is a 6AU6 preamp, a loafing 6AQ5 driver/phase inverter to PP 6AQ5's. Parts on hand determined most of the circuit.

Antenna is a 34' wire in the attic and using the house copper pipes as the ground/counterpoise. Fed with RG6 to the TX in the LR. The signal is still loud back 1000' which is on the neighbors property and all woods where several of my Beverage antennas run.

A simpler version would be a choke coupled Heising type modulator and just a 6AU6, 12AT7. RF out would be about half the above.

Audio shaping can be done with either as well as clipping and compression for more "punch"

Carl

276merc
Member
Member

Number of posts : 23
Registration date : 2013-07-02

Back to top Go down

Re: Home AM transmitter

Post by Sponsored content


Sponsored content


Back to top Go down

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum