That's a pretty clean design there with the chassis setup! personally I would have mounted the transformer and tuning coil on the top to make it look more vintage, but nice job! I can pick up mine all over the house with a 3 foot wire antenna. your soldering looks excellent but i'd still check for cold solder joints, mine didn't work at all at first because I had a couple.
@coolbluelights Thanks. I thought about mounting the transformer on top but decided to make it as clean as possible. I broke down and bought an SSTRAN kit a while back and I'm very happy with that. I still fiddle with this one occasionally though. But the flaws stand out the more I play with this design. You need a fair amount input volume to get good modulation at the output and the modulation fights the oscillator.
I've got all the parts for that 6888 TX now so I'll have to try that sometime.
@outatime1955 Thanks. I've seen a version of this transmitter with a 12J5 pre-amp for the audio. Never anything for RF amplification though. One critical flaw with this design is that there's no matching network to the antenna. I think I'm going to end up building the 6888 design from the Antique Radio forum I mentioned in this video. It does have a matching network as well as crystal controlled carrier frequency and it seems to be the preferred design of all the tube radio guys.
Looks great - what fun. Do you get a lot of range from it? My guess is the signal will go as far as the antenna, so if you have a LONG antenna it could cover a pretty large area. We used to couple "carrier current" signals on the AM band into the telephone wires when I was in college, and it covered the whole campus very well!
@af4k Yeah, I've discovered the range is heavily dependent on the length of the antenna wire. Although with a sensitive radio, I can pick it up all over the house (with lots of static).
@MIKEPREAMP The tube is a 12SA7. It's normally used as the mixer/IF oscillator in a super heterodyne receiver but here we're using it to generate the carrier frequency and modulate the audio on to it.
@cleosimble For the antenna connector? I don't see why not. I chose the binding post just because I had it handy and I knew I was just going to use a simple long bare wire as the antenna.
That's a pretty clean design there with the chassis setup! personally I would have mounted the transformer and tuning coil on the top to make it look more vintage, but nice job! I can pick up mine all over the house with a 3 foot wire antenna. your soldering looks excellent but i'd still check for cold solder joints, mine didn't work at all at first because I had a couple.
coolbluelights 3 months ago
@coolbluelights Thanks. I thought about mounting the transformer on top but decided to make it as clean as possible. I broke down and bought an SSTRAN kit a while back and I'm very happy with that. I still fiddle with this one occasionally though. But the flaws stand out the more I play with this design. You need a fair amount input volume to get good modulation at the output and the modulation fights the oscillator.
I've got all the parts for that 6888 TX now so I'll have to try that sometime.
caiserECEguy 3 months ago
@outatime1955 Thanks. I've seen a version of this transmitter with a 12J5 pre-amp for the audio. Never anything for RF amplification though. One critical flaw with this design is that there's no matching network to the antenna. I think I'm going to end up building the 6888 design from the Antique Radio forum I mentioned in this video. It does have a matching network as well as crystal controlled carrier frequency and it seems to be the preferred design of all the tube radio guys.
caiserECEguy 6 months ago
I have ripped apart old PC power supplies like you have.
BUT, I nearly always use the case of the power supply as well as the fan and other parts.
The PC power supply takes AC and creates DC that is run into a toroid transformer at peak line current.
Take out the printed circuit board and add a small piece of perf board or carefully cut the PC board apart for the circuit wanted.
Add the tube and AC transformer, most if not all of the parts needed for the transmitter will come from the defunct PS
Arabhacks 10 months ago
Looks great - what fun. Do you get a lot of range from it? My guess is the signal will go as far as the antenna, so if you have a LONG antenna it could cover a pretty large area. We used to couple "carrier current" signals on the AM band into the telephone wires when I was in college, and it covered the whole campus very well!
af4k 1 year ago
@af4k Yeah, I've discovered the range is heavily dependent on the length of the antenna wire. Although with a sensitive radio, I can pick it up all over the house (with lots of static).
Pirate radio is the best kind.
caiserECEguy 1 year ago
nice clean job!!! -Al, KF7DMY
ObamaTaliban 1 year ago
What type of tube?
MIKEPREAMP 1 year ago
@MIKEPREAMP The tube is a 12SA7. It's normally used as the mixer/IF oscillator in a super heterodyne receiver but here we're using it to generate the carrier frequency and modulate the audio on to it.
caiserECEguy 1 year ago
could i use a PL 259 connector instead of what you said
cleosimble 1 year ago
@cleosimble For the antenna connector? I don't see why not. I chose the binding post just because I had it handy and I knew I was just going to use a simple long bare wire as the antenna.
caiserECEguy 1 year ago