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Nice job Bob. That is a cool and unique looking case. The tube layout on back cover is awfully similar in look to many I have seen on Airline sets by Wards, so who could have built this one? Wells Gardner?
Anyway she looks fine and as Gary indicated SW for another day, given what you may find on SW not a biggie in my book.
Paul
Tubetalk1
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Not quite done with this radio yet. I've read about folks adding an AUX input jack so you could plug in an MP3 player or a Bluetooth receiver and this radio seemed like a good one to learn on. I looked at powering a bluetooth board within the chassis but decided on an easier route for my initial go at this. I bought a cheap
bluetooth receiver, some 3.5mm stereo jacks and some small SPDT switches. The stereo jack went into the hole where the phono jack originally was and the switch into a small hole that was above the phono jack. The left and right stereo lines are combined with two 1k resistors and a 10k resistor as shown below. All in all it seemed to work out fine. AM in our area is terrible and this set will likely be sold locally so folks can hear something beyond talk radio if they so desire.
I think I could have used a switched jack to eliminate the SPDT switch but when first thinking about this I didn't realize that.
[Image:
https://www.dropbox.com/s/7x3z02r9vquvvg....jpg?raw=1]
Under the chassis the stereo jack and switch are in the lower right corner with the shielded line going to the high end of the volume pot.
[Image:
https://www.dropbox.com/s/jp81lr78r2hbaw....jpg?raw=1]
[Image:
https://www.dropbox.com/s/3sjs7bafdsuuer....jpg?raw=1]
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I think you are better off with the switch. This way, you can leave the MP3 connection in. The only thing I would do differently is not have the 10K resistor. This would allow a true (ceramic) Phono connection (which can still use the 3.5mm jack using the correct adaptor) or other input that is lower than the headphone output. Ensure that there is still a cap somewhere in the circuit between this input and the 1st AF Amp grid.
If the dropoff does not coincide with switching bands on the Radio, it could be an issue with the 1st RF or the Convertor Tubes. 6SK7s and 6SA7s were common RF Amps and Convertors for shortwave radios up to about 18MHz, but i am sure that their performance falls off. If you hae a shortwave that works well on that band, try swapping the tubes between the 2 radios. This will also be a good test for your Sig Genny
Best Regards,
John MrFixr55
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
(This post was last modified: 06-14-2022, 04:27 PM by
MrFixr55.)
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Thanks John,
Yes there is a 0.01uF cap on the wiper arm of the volume pot. Thanks also for the thoughts on the SW issues.