Hello All,

Just acquired a 1940 RCA T63. Works great on broadcast band, but no shortwave. Checked the obvious- osc. coils, antenna loops, caps off band switch. Any other ideas?

Hi Bill

Radio uses the same circuitry for broadcast and short wave. Short wave will require an antenna.

If you still don't receive stations try another 6SA7 tube. Or better yet use a 6SB7Y as replacement. This circuit is an oscillator and will fail first on higher frequencies like short wave.

http://www.nostalgiaair.org/PagesByModel/829/M0015829.pdf

Norm

:Hello All,
:
: Just acquired a 1940 RCA T63. Works great on broadcast band, but no shortwave. Checked the obvious- osc. coils, antenna loops, caps off band switch. Any other ideas?
:

:Hi Bill
:
: Radio uses the same circuitry for broadcast and short wave. Short wave will require an antenna.
:
: If you still don't receive stations try another 6SA7 tube. Or better yet use a 6SB7Y as replacement. This circuit is an oscillator and will fail first on higher frequencies like short wave.
:
:http://www.nostalgiaair.org/PagesByModel/829/M0015829.pdf
:
:
:Norm
:
::Hello All,
::
:: Just acquired a 1940 RCA T63. Works great on broadcast band, but no shortwave. Checked the obvious- osc. coils, antenna loops, caps off band switch. Any other ideas?
::
:
:

Could be a shorting C27 or a defective contact in the wafer switch. C band loop and/or associated primary may have a problem.
Johnnysan-

Hello All,

Thanks for the replies. Ran another aerial to connection (opened link) with no results. Also changed 6SA7 with no luck. Picking up static with and without external aerial. Any way to bypass the C loop and run external aerial right to the set for testing? I'm thinking along Johnnysan's line that the problem is in the loop antenna.

::Hi Bill
::
:: Radio uses the same circuitry for broadcast and short wave. Short wave will require an antenna.
::
:: If you still don't receive stations try another 6SA7 tube. Or better yet use a 6SB7Y as replacement. This circuit is an oscillator and will fail first on higher frequencies like short wave.
::
::http://www.nostalgiaair.org/PagesByModel/829/M0015829.pdf
::
::
::Norm
::
:::Hello All,
:::
::: Just acquired a 1940 RCA T63. Works great on broadcast band, but no shortwave. Checked the obvious- osc. coils, antenna loops, caps off band switch. Any other ideas?
:::
::
::
:
:
:Could be a shorting C27 or a defective contact in the wafer switch. C band loop and/or associated primary may have a problem.
:Johnnysan-
:
:
:
:

Hi Bill,

I just worked on one of these today with no shortwave reception while the broadcast band was functioning normally. Found an open 0.0056 microfarad capacitor in the oscillator circuit between the band switch and the oscillator coil. After replacement, the shortwave band worked normally.

Lou

:Hello All,
:
: Thanks for the replies. Ran another aerial to connection (opened link) with no results. Also changed 6SA7 with no luck. Picking up static with and without external aerial. Any way to bypass the C loop and run external aerial right to the set for testing? I'm thinking along Johnnysan's line that the problem is in the loop antenna.
:
:
:
:
:
:
:::Hi Bill
:::
::: Radio uses the same circuitry for broadcast and short wave. Short wave will require an antenna.
:::
::: If you still don't receive stations try another 6SA7 tube. Or better yet use a 6SB7Y as replacement. This circuit is an oscillator and will fail first on higher frequencies like short wave.
:::
:::http://www.nostalgiaair.org/PagesByModel/829/M0015829.pdf
:::
:::
:::Norm
:::
::::Hello All,
::::
:::: Just acquired a 1940 RCA T63. Works great on broadcast band, but no shortwave. Checked the obvious- osc. coils, antenna loops, caps off band switch. Any other ideas?
::::
:::
:::
::
::
::Could be a shorting C27 or a defective contact in the wafer switch. C band loop and/or associated primary may have a problem.
::Johnnysan-
::
::
::
::
:
:

You might try a little "brute force" just to get a little closer.
Set the band to SW at some frequency like 5 MHz or 10mhz.. whatever.
Then set your modulated signal generator to that same freq and place the output lead in very close proximity to the SW antenna lead. Then tune around a bit to find that strong signal. Or tune the generator one way or the other.
If you do hear the signal... it may be nearby but slightly off-freq .. but at least you know you've force it through... then reduce to generator output more and more.

Hi Bill,

Just worked on one of these today with no shortwave reception while the brroadcast band was functioning normally. Found an open 0.0056 microfarad capacitor in the oscillator circuit between the band switch and the oscillator coil. After replacement, the shortwave band worked normally.

Lou

:Hi Bill
:
: Radio uses the same circuitry for broadcast and short wave. Short wave will require an antenna.
:
: If you still don't receive stations try another 6SA7 tube. Or better yet use a 6SB7Y as replacement. This circuit is an oscillator and will fail first on higher frequencies like short wave.
:
:http://www.nostalgiaair.org/PagesByModel/829/M0015829.pdf
:
:
:Norm
:
::Hello All,
::
:: Just acquired a 1940 RCA T63. Works great on broadcast band, but no shortwave. Checked the obvious- osc. coils, antenna loops, caps off band switch. Any other ideas?
::
:
:

Hi lou,

thanks for the response. i replaced all caps a few days after the last post in Jan. and the short wave worked fine. Apparently this one capacitor was the problem here too.

:Hi Bill,
:
:Just worked on one of these today with no shortwave reception while the brroadcast band was functioning normally. Found an open 0.0056 microfarad capacitor in the oscillator circuit between the band switch and the oscillator coil. After replacement, the shortwave band worked normally.
:
:Lou
:
::Hi Bill
::
:: Radio uses the same circuitry for broadcast and short wave. Short wave will require an antenna.
::
:: If you still don't receive stations try another 6SA7 tube. Or better yet use a 6SB7Y as replacement. This circuit is an oscillator and will fail first on higher frequencies like short wave.
::
::http://www.nostalgiaair.org/PagesByModel/829/M0015829.pdf
::
::
::Norm
::
:::Hello All,
:::
::: Just acquired a 1940 RCA T63. Works great on broadcast band, but no shortwave. Checked the obvious- osc. coils, antenna loops, caps off band switch. Any other ideas?
:::
::
::
:
: