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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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3rd Aug 2021, 9:28 am | #1 |
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AWA 38a Australian radio volume fault !
I have just rebuilt this radio, having painted the chassis, and it works which is always a relief, but it had this problem before, the volume is flat out, by bridging the 500k R12,with a 56k resistor I get it to a reasonable level and it's controllable. I read somewhere this is a reflex circuit. I can't get my head round the circuit and how it works.
Mick. Last edited by vinrads; 3rd Aug 2021 at 9:41 am. |
3rd Aug 2021, 10:15 am | #2 | |
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Re: AWA 38a Australian radio volume fault !
Quote:
If that's any help. Lawrence. Last edited by ms660; 3rd Aug 2021 at 10:27 am. Reason: extra info and correcting an editing error |
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3rd Aug 2021, 1:20 pm | #3 |
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Re: AWA 38a Australian radio volume fault !
Thanks Lawrence I have just re drawn the diagram , with your description it is making a bit more sense now ,I still don't understand why I have max volume , having said that it has been worked on before I think I need to go through the component layout , Cheers Mick.
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6th Aug 2021, 10:31 am | #4 |
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Re: AWA 38a Australian radio volume fault !
Having been round and round in circles ,chasing the odd fault I ordered a detector valve a 6b7 ,It arrived yesterday fitted it guess what didn't cure it ,still full volume and the control did next to nothing!, so in desperation I decided to do a re alignment 460 kc/s the third i.f tx was quite a way off , to my surprise it cured the fault , I guess something to do with the reflex cct I notice there is an gain switch at the front end which also now works , I never did like reflex circuits.
I will be doing a full write /up on restoring the chassis and cabinet on this radio . Mick. Last edited by vinrads; 6th Aug 2021 at 10:36 am. |
6th Aug 2021, 11:13 am | #5 |
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Location: Mareeba, North Queensland, Australia
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Re: AWA 38a Australian radio volume fault !
ALL Australian radios used 455 kHz IF frequencies. I have never seen 460kHz here. JUST an observation.
Joe P.S. Communications sets here had a variety of oscillator / IF frequencies, some above 30 MHz, some around 1.8 kHz, followed by the standard 455 kHz. j.b. |
6th Aug 2021, 11:32 am | #6 | |
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Re: AWA 38a Australian radio volume fault !
Quote:
https://www.kevinchant.com/uploads/7...8231/38_41.pdf Lawrence. |
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