Carlos

Looks great from here. Makes a good example for others to follow.

Thanks Norm ! Should I use a long wire antenna or one of those telescoping antennas ?

Carlos

Carlos

Try different antennas. I usually have a 3 foot whip. Tom uses 10' or so of wire. Longer antenna will cover a greater distance but loads down the output.

My antenna here in the house is 10-12ft draped over a curtain rod(I've never measured it), mainly it's important to keep the antenna away from electrical wiring, as that will induce hum... On the curtain rod it is virtually hum free, when I tried it along the baseboard the hum was terrible...

Tom

I'll be switching over to the new parts kit in the near future but not in time for Kutztown. All the Kutztown broadcasters being worked on will still work and can be upgraded later.

Hello Tom,
I think the Curtain rod must help shield the antenna away from the
AC .
That is one my major problems finding a wall that does not cause ac hum with my Sstran.

I need to get my rear in gear and build one of those tube amps.

I've got the parts laying around the house including the wooden atlas case I got from you.

So if I understand the new one your having input gain overload .
of the am tube transmitters what has been your best one yet.
Far as tube type and design.

Far as 24 volt transformers I have like 2 dozen laying around my place from old commercial appliances and furnaces.

Any wheres from 20va to over 100 va

This 12AV6-12CS6 Tx does not overload nearby radios... It and the 12AU7-6GY6 Tx are the only ones I have that do not... Oops make that three, the 30V B+ 12EG6 Tx is fine at close range... With short enough antenna, any of them can be used at close range....

The 6888-6GY6-12CS6 all sound approx the same, I couldn't tell one from the other if I didn't know which one was operating...

The 12AV6-12CS6 Tx requires a transformer with 24v & 36v windings(or at least two 24v windings), a single 24v isn't going to provide enough voltage...


Tom

Sweet, a use for those Electronics Goldmine transformers I can't seem to find any other use for yet ordered 2 of!

Hello Tom,
Yes I know that and I do have like 5 or 6 with dual windings

the one big one even is multi 120-480 input it's square D power trans.

100 va

Rich

ok i put this transmitter together and i hooked it up to my laptop as an audio source. How do i get this thing to work now ? Do i adjust the variable cap somehow and wait until i hear the music on the radio ? I am using a 10 foot piece of insulated wire as the antenna and I draped it over my curtain.

please help.

Carlos

Ahhh the fun part...


It should operate even with the cap mistuned(range would be reduced)... Do you get a carrier??? If not possibly the the osc is installed incorrectly??? Is there a negative 5v on pin 7 of the osc??? It would also be a good idea to check the tube voltages...


Tom

I have a -4.87v on pin 7 of the 1000 KHZ oscillator. How do i work this thing ? do i tune the radio first on an empty radio station and then tune the variable cap ?

What are the voltages on the tubes supposed to be so i can check them ?

Carlos

Here are my tube voltages.

12CS6

pin1 -6.5volts
pin2 3 volts
pin3 4.88 volts
pin4 4.90 volts
pin5 141.6 volts
pin6 77.8 volts
pin7 0 volts

12AV6

pin1 -0.848 volts
pin2 0 volts
pin3 -4.90 volts
pin4 -4.94 volts
pin5 not connected
pin6 not connected
pin7 74.2 volts

I hope this helps

Carlos

I got it working, I basically changed the wiring to the filaments and it started working. I am adjusting the variable cap now and playing with the antenna to get the best signal out.

Carlos

I have a question there is a radio station that plays on 990 KHZ and it seems to be competing with some of the radios that i am trying to listen on when i am broadcasting on 1000 KHZ. Do you think it would be better if I tried the other 1228 oscillator chip ? The signal does not seem to go very far as it fades just in the other room from where i am transmitting. Maybe i need to try a whip antenna instead of this long wire ?? I will keep trying tomorrow, I need a break

Carlos

Do you think it would be better if I tried the other 1228 oscillator chip ?
----------------------------------------------------------------
Don't forget you have to change the coil also if you try the 1228.

If they are strong, adjacent stations can be a issue but I think you may have a tuning problem... I have a local on 1010 and could easily cover the house on the antenna hanging on the curtain rod...

If you have a scope, connecting the probe to the antenna insulation works nicely, just adj for max deflection... Or you can use a radio with tuning eye to do same... If max is with the tuning cap at max or minimum then some tweaking is going to be necessary... Max is easy, add 47-68pf across the tuning cap and try the tuning again... Max signal at minimum cap setting usually requires a coil with less inductance be used...

Tom

I believe I get the best signal when i turn the screw on my variable cap countercloskwise which I think would indicate that i need a smaller coil on the antenna right ? Right now I have a 680uH so I will try with a 470uH which is all i have to try with

Bill Hamre has also agreed to graciously send me a 1228 KHZ coil to try as well. I cant say enough good things about Bill Hamre, he has supplied me with all the parts and then some !!

If anyone wants to build this antenna circuit I highly recommend you send Bill Hamre a note and order the kit from him, honestly folks I have seldomly found a person more willing to help than he is.

THANKS AGAIN BILL !!

Carlos

Carlos

Are you using the 680uh coil from Mouser???

Tom

Yes i am using the 680uH from Mouser the one that costs about a dollar something. part number 807-1025-88K

I also have some of the 434-23-681J on hand.
Carlos