In a word, outstanding.



Based on this 1928 Grimes, "period correct" could be Kurz-Kasch pointer knobs. If you'd like the pair in the foreground, I'll send them gratis. I can probably find a power switch too.

Thanks for the comments!


The audio bypass and power supply filter caps are modern so I hid them inside a condenser block, as you surmised. All the RF caps are antique aerovox micas and the audio coupling is a aerovox paper.


The '66 worked OK if a 2 mfd or so capacitor was added before the choke but since transformers with both 2.5 and 6.3 filament windings are quite hard to find, I went with the '80. Also it looked a little silly with one tube three times the size of the others.



Thanks Alan. Those look great! I will send PM.

.....
I tested the range today. I set up both the transmitter and a ten foot vertical antenna 25 or so feet off the ground, set it to around 1200kc/s and verified that the PA power input was 100 mW. I then walked away from it while listening to a Walkman. The signal was intelligible up to around 0.5 miles away, at which point the reception was getting pretty spotty. Thats a lot farther than I need to transmit.

The No. 80 is super fine. Wow! Simply far out!

Excellent!!!!

That is marvelous, Jon!

WOW


Now that is a labor if LOVE.

Just Beautiful workmanship all around.
Drooling all over my keyboard.

Bob T.

Gorgeous! You give all of us something to shoot for.

Jon,
Truly a work of art.

Maybe you could share some of your building tips with us mortals. Like how do you do the beautiful wire lacing?

Awesome!

All Drooling!

Thanks!

The instructions I used to lace the cables are here. http://www.dairiki.org/hammond/cable-lacing-howto/
I had to lace it with the wires installed though, because the audio transformers had wire leads instead of solder lugs.

Here it is with the proper knobs and power switch; thanks Alan.

Absolutely beautiful Jon. Very few times has a project simply made me drool and salivate with eny. Your craftsmanship is simply unmatched. I cannot recall seeing a better constructed/looking project---ever.

My hat is off you my friend.

Dave

That loud iron sounding clonk you just heard was my jaw hitting the floor....

That is absolutely outstanding workmanship!!! Write this thing up and submit it to something like Antique Radio Classified, that would make a great article!

Wonderful! Do you have a parts list? Were all of the parts old stock or used? What do you use for input? What inputs could be used directly, and which would need some sort of modification?

The following were new-old-stock:
Resistors
Mica and paper condensers
Tube sockets
National "B" dials
One of the two output transformers comprising the modulation transformer
Solder lugs
Volume potentiometer
Grid caps

The rest of the vintage components were used

Wiring, (hidden)electrolytic capacitors, chassis aluminum, coil forms, antenna coil shield, standoffs, L-brackets, and miscellaneous grommets, nuts/bolts/washers were modern.

I use an mp3 player for input.
It needs to be set for mono. Otherwise one would need to add another input binding post and use two resistors to convert the stereo to mono.

Hello Jon,
Wow you out did your self on this one

Rich

Not than anyone else is too likely to build this transmitter, but I added 3 improvements.

1. Got rid of the voltage divider for the AF amp screen. Screen voltage now derived from modulator cathode. Eliminates 2 resistors.

2. Added a resistor from the secondary of the modulation transformer to the plate of the AF amp. Reduces the distortion inherent to pentodes and prevents attenuation of high and low frequencies by the modulation transformer(s).

3. Changed rectifier tube to an 84, the full wave rectifier originally designed for the 6.3 volt auto tubes. Harmonizes appearance since all tubes are now same size and shape. Eliminates the need for a separate filament winding. Slow warmup to prevent voltage surge on startup. While a globe 84 is less common than an 80, you won't go bankrupt buying it. This eliminates all popular, high dollar tubes from the transmitter.

With the quality of you craftsmanship, probably everyone is scared to try...

I've thought of trying but would have to round up the globe 38s and 84, 80s are no problem... A unorthodox arrangement with the globe 80 surrounded by the smaller tubes should be interesting...

Tom

Like wow!!!!