Alan, send me a PM with your address and I'll send you one of each missing piece. Pay for postage after you receive items.

Dale

And I can't find a suitable C6 (0-50pf). Can someone post a link or part source of one that works?
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I think we uped this to 0-75pf when the as-builds were saying that 0-50pf was a little light weight. Dan's small parts and kits (just google) has a "10-100pf ceramic trimmer capacitor" for $1.25 ea or 10/$6.50". Also, they have 220uh choke 10/$1.50 if any one is going with the 1228khz osc.

12AV6-12CS6 Transmitter(Revised Schematic)
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35Z5
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just noticed that this thread exceeds the 12CS6 thread for total views, very impressive.

Yes the 0-50pf proved to be a little low but I'm generous with antenna length(requires less cap), probably something more in range of 55-60Pf was actually needed... As long as that range is obtainable, amount of capacitance above or below makes no difference... I have one on breadboard with a 10-365pf AA5 cap...

The 10-100pf would be fine...

My iteration after 4 years of adjustments: Bluetooth, built-in voltage regulator takes any wall wart, works the same on 1228 KC or 1544 KC, about 1" X 4". Love the heck out of the original idea.

Dale

Very nice work.

Have there been any recent improvements in sound quality? I built one and the sound not very good.

The sound is good on the three I built. It's not hi-fi but it isn't meant to be. For broadcasting OTR it's fine.

Larry

I thought I'd take a stab at a parts list "take off" in case anyone just lacks a few parts in the junk box to build this. These are all Radio Shack part numbers, prices range from $1-$2.50 each:

1000 uf 35v 2721032
200uf 35v 2721029
Bridge 2761181
386N 2761731
LM7805 2761770
.01 50v 2721065
10uf 35v 2721025
.01 500v 2720131
1k 2711321

What would be interesting is if this could be built on a Raspberry pi 2 or 3. That would give the transmitter built in streaming audio and built in audio processing (stereo tools has a version for the pi) which would make for a self contained transmitter with everything needed all in one box.

If anyone needs to re-stock the junk box for this and other projects I did a Dan's take off:

.1 50v 100/$5 (but long lead)
470 pf 2% 100v 100/$5
.01 50v 100/$5 murata
10uf 16v tan 4/$1
all chokes 10/$1.50 (but can't mix)
red or yellow LED's 9-12v 25/$1.00
LM7809 $0.59 ea
386-1 5/$2.50
postage of $7.50 is drpped at orders over $50 but only with snail mailed usps money order

My order for some 10-100pf ceramic trimmers just arrived from Dan's if anyone needs one just PM me with a mailing address.

Here is my second version. My first version was built on a breadboard and it worked "right out of the box."
The LED was on full bright with no change to C6. I have not tested how far it goes as I will use this in close proximity to the radio.
This second version is the same but built on the perf board.

It works great and sounds good, no hum or obvious distortion. I didn't use the 5k pot on the audio input because I can adjust the PC or
mp3 player volume. Those two 1k resistors might work a bit higher like 2.7k or 3.3k. And I wonder if a simple filter or RC feedback loop might increase the high
end freq response. Boosting the 2KHz-8Khz range helps. I can do this on the PC's audio output.

I got a few uncommon parts from Dale - much obliged!
I see the parts list posted recently, what about part numbers for the RF parts like C6, L2 and L1. I might want to build another one of these babies.
Right now I'm listening to Raymond Scott's Powerhouse on an RCA 87 console with it.

Alan

So I've running old tunes through this little LM386 transmitter into my RCA 87 console and it just sounds great.
Begin The Beguine, Let's Dance, The 5 0'clock whistle, Sonny Boy - Al Jolson, It don't mean a thing, Sing Sing Sing, and it just sounds great.
You don't have to tell me, it's an inanimate object but at the same time I kinda feel like the old RCA is happy playing it's own tunes again.
It sure seems like it is. (and somehow sounds like it was meant to sound).

Can you post a schematic of this, with part specifications? I'd like to try building one.

The schematic is one page one of this thread, and updated one page 41 (unless there's another update that I missed).

Page 41 -> http://antiqueradios.com/forums/viewtopic.php?f=12&t=193042&start=800

And also below (I had to scale it down to fit, go to the original that is bigger and easier to read):

What is the bandwidth of these transmitters using the 1MHz oscillator?

I can tune it on a receiving radio all the way between 998 and 1002. At 997 and/or 1003 the signal fades. Is that what you mean?

Larry

That looks pretty tight, and I wouldn't think that it would interfere with broadcast stations at 990 or 1010 Kc.

At close range mine fades at 996 & 1004, but really if it were a 30Kc spread no one is going to care... IBOC wipes out channel either side of center freq...

On 1228 and "extra" antenna, I can wipe out the local 1230 for maybe 30 feet, then it's no contest...


Tom