RCA Q-103 tube ? - Printable Version
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+--- Thread: RCA Q-103 tube ? (/showthread.php?tid=14543)
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RE: RCA Q-103 tube ? - Eric - 05-19-2016
(05-17-2016, 04:33 PM)Radioroslyn Wrote: Well You could try tuning the bcb oscillator by monitoring it's signal in a well calibrated receiver. Use C-6 to set the osc signal heard in the well calibrated receiver at 1755kc (1300+455kc) with the dial set at 1300kc on the RCA. Same thing for the low end of the band. Use L-9 to set the osc heard in the well calibrated receiver at 1055kc (600+455kc) with the RCA dial set at 600kc. It's not uncommon to have so interaction between these two adjustment so you may have to adjust these a few times to get it on the nose. If you can't get the osc to tune from 1055 to 1755kc and your bandswitch is good and clean them I'd replace C-8 and C-11.Set the radios up like you said the signal was picked up at 1755 and peaked using C6 and 1055 using L9 I would say it is a little better but still need to hook up my garage antenna to really get anything.
The other thing that comes to mind is interference from other electrical devices like cell phone/lap top chargers or computers. They use switching mode power supply and generate a lot of rf noise which can be very strong.
Terry
RE: RCA Q-103 tube ? - Radioroslyn - 05-19-2016
Good! Now we know that the oscillator is working and is working at the proper tuning range. This will assure that the stations received will be on there proper places on the dial.
Part 2
With your antenna connected tune in a local station near 600kc then adjust L2 for loudest signal from the spkr. Find a local station near 1300kc and C1 for loudest from the spkr.
Just for grins tune your generator to 455kc. Connect the output to the antenna post of your Hammerlund and listen for it's signal @ 910kc (that would be the generator's 2nd harmonic 455x2=910) to see if your generator is on frequency @455kc. If your not hearing a signal at 910kc then retune the generator till you do then re adjust the IF transformers in your RCA noting that all of the adjusts (4) do make some difference when adjusted. If not there is a problem with the IF transformer.
Just to be clear your set doesn't have a built in loop ant it does require an external ant to hear much of anything. With that being said it should be able to pick stations with 10-15' of wire hooked up to it. I would think that WSB should knock your sock off as I can get it up here near Phila.
Sorry we have to have done this sort of basacwards but I want to be sure there wasn't a problem with the osc. It's doing it's thing! This set going to make you a pro at fixin'
Terry
RE: RCA Q-103 tube ? - Eric - 05-20-2016
(05-19-2016, 06:16 PM)Radioroslyn Wrote: Good! Now we know that the oscillator is working and is working at the proper tuning range. This will assure that the stations received will be on there proper places on the dial.Everything came in great, picked up the 910 on the Hammerlund as close to perfect as you can get on the scale of the signal gen for 455. I think this RCA set is very sensitive and the adjustments are very touchy compound this by my not having a long enough antenna at the start of this (about 8-12") right now I have a 6' wire attached which I attache my garage ant about 20. Since the instruction doesn't give a length for the antenna what would be good 10'?
Part 2
With your antenna connected tune in a local station near 600kc then adjust L2 for loudest signal from the spkr. Find a local station near 1300kc and C1 for loudest from the spkr.
Just for grins tune your generator to 455kc. Connect the output to the antenna post of your Hammerlund and listen for it's signal @ 910kc (that would be the generator's 2nd harmonic 455x2=910) to see if your generator is on frequency @455kc. If your not hearing a signal at 910kc then retune the generator till you do then re adjust the IF transformers in your RCA noting that all of the adjusts (4) do make some difference when adjusted. If not there is a problem with the IF transformer.
Just to be clear your set doesn't have a built in loop ant it does require an external ant to hear much of anything. With that being said it should be able to pick stations with 10-15' of wire hooked up to it. I would think that WSB should knock your sock off as I can get it up here near Phila.
Sorry we have to have done this sort of basacwards but I want to be sure there wasn't a problem with the osc. It's doing it's thing! This set going to make you a pro at fixin'
Terry
Thanks for the help!
Eric
RE: RCA Q-103 tube ? - Radioroslyn - 05-20-2016
Your welcome!
The 19 minute answer to your question can be found here https://www.youtube.com/watch?v=PGijDgDFfgg
The am bc band covers 500 to 200 meters that's in wave length. So to have a resonant ant at the bcb you are looking at about 1500 feet at 6ookc. Not many folks have that kind of real estate so most ant back in the day where erected on poles at the ends of the roof of your house maybe 60' long and up in the air 35'.
Then you have the feed wire running from ant down to the set maybe another 50' or so. On average about 100'.
Terry