I'm totally blown away by the performance of this transmitter. I followed Norm's schematic to a tee, and used one of my already wound toroid coils because space was at a minimum with this Blonder Tongue converter donor. It worked first try!

I had a 760kc crystal oscillator, but bought a 1000kc and 1228kc from Mouser. All are easy to peak with the var cap. My hat's off to you Norm. This sounds every bit as good as my 6BM8s and AMT3000 and a lot cheaper. Tomorrow I'll try different antennas. Oh yea, I have to lower the tube socket ¼", damn.

[

Nice.

Great job. What were the part numbers for the crystals from mouser, i'm not sure what one to buy. Does any one have a tube for it they would be willing to part with? Thanks for the help, and great job.

Jeremy

I used full sized oscillators because they plug in to 14 pin DIP sockets.
The 1mHZ (1000kHZ is http://www.mouser.com/search/ProductDet ... 0-TCF100-X

Looks like you are getting good at these builds, nice job...

Mike where did you get the 760KHz osc??? We have locals on 1010 , 1230 and 1600, so till I find something other than the std osc I'm doubting I could use one of these xmitts... BTW 760 is the frequency I use on my 6AQ5 xmitt...

Hi Mike

You did a great job. Even like your perf board mounting of the transformer. Mine have been below chassis but looks good on top.

Like your idea of using different frequency oscillators. 1000 KHz is easier to find but it would be a problem in Wahington and Illinois. Both of these areas have clear channel stations on this frequency.

I can mail a 6888 tube early next week to anyone interested in building this circuit. Will be away the rest of this week. I will show one of these transmitters at the SCARS meet in Carlsbad, CA later this week.

What's the small toroid looking coil in back of the variable cap? Is it commercial? I'm guessing that the variable cap is not in the circuit, since it's crystal controlled. A fair number of these transmitters lend themselves to the UHF enclosures. Would there be a way to use the variable cap to change the transmitting frequency? I'm long on soldering but short on theory.

You need the variable capacitor to tune the circuit, which consists of the toroid and the capacitor to resonance with the crystal.
Curt

Hi norm, Would you please send me a 6888. I'll send a PM after lunh when i have a little more time, thanks for the offer.



edit:
Is there any other more common tubes that could be substituted otherwise?

Actually it's 780KHz, my error. I found a box full at All Electronics, a buck each. I know the 1.228KHz (Mouser) is a little off freq but even the digital radios seem to tune ok.

The schematic calls for a tuning coil and var cap. I used what I had that would fit. I really liked the idea of using an AA5 antenna. In fact I was going to use a small bakelite radio for this transmitter. It wouldn't look out of place.

What I'm really surprised about is the volume. Because there is no internal amplifier stage, the audio transformer turned backwards gives it the boost and the earphone (not line out) output of the CD player adjusts the gain. Part of the simplicity of Norm's design:!:

DAMN.... We have a local on 790 as well... Can't win, I give up...

Norm,

I too would like to take advantage of your 6888 tube offer. Looks like a great quick project. PM on the way. Thanks in advance.

73's

Hi

I received requests for 6888 tubes. I'll mail them out early next week. Will be away for a couple days.

used full sized oscillators because they plug in to 14 pin DIP sockets.
The 1mHZ (1000kHZ is http://www.mouser.com/search/P ... 0-TCF100-X
by mike toon
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I'm about to gather parts for a 6888 and the osc above is $1.50 with $6 shipping. I'm wondering would it make sense for me to buy qty of 10 then resell them to others one at a time at cost or not? AND perhaps likewise with the F-82-61 toroid.

Bill

There should be enough people needing crystal oscillators. I mailed off more than twice that many tubes. Crystal oscillators weigh little & can be mailed with a single stamp.

im very interested i wouild like a tube too norm

Anyone still wanting to build one of these transmitters send a PM with your mailing address. I'll send a 6888 tube. Prefer to have address arranged so I can cut and tape it on a mailer.

Bill, that sounds like the thing to do. The parts not in peoples junk box might be the crystal oscillator, 5.1V zener diode and toroid.

The coil can be almost anything. I tried a solenoid, spiderweb and even an AA5 antenna. I settled on the toroid because it's not affected by the metal chassis I had it mounted inside.

I also used the little audio transformer from Radio Shack ($3) because it's small, although Norm says almost any audio transformer will work. Connected backwards of course.
http://www.radioshack.com/product/index ... 2103254&cp

Hi Norm, I just got a look at the transmitter on another thread and I sure would like a copy of the schematic.
Ed

Hi Ed

Mike posted a schematic here:

http://antiqueradios.com/forums/viewtopic.php?t=63310

I am also sending out information with 6888 tubes. Don't know what happened but got 4 requests in the past couple hours.