I HAVE A PHILCO 40-155 RADIO THAT PLAYS GOOD ON BROADCAST AND POLICE BAND BUT WHEN I SWITCH TO SHORT WAVE 6-18, IT BECOMES VERY NOISY AND WILL NOT PICK UP SIGNALS. WHEN I GROUND ANTENNA TERMINAL 3 TO THE CHASSIS (WHILE LOOP ANTENNA IS STILL CONNECTED) IT PICKS UP GREAT BUT THEN WHEN I SWITCH BACK TO BROADCAST THE SIGNALS ARE VERY WEAK. (THEN I HAVE TO REMOVE THE GROUND WIRE FOR IT TO PLAY AGAIN) SCHEMATICS CAN BE FOUND IN RIDER VOLUMN 10 & 12. ANY IDEAS ON WHAT TO DO WOULD BE APPRECIATED.
THANKS MINGRAM

Mingram - without seeing the schematic I might hazard a
couple of guesses and possible tips. The local oscillotor
may be trying to dropout at the higher frequencies or
you may have a dirty section(s) in the bandswitch. Try
substituting the osc/mixer tube and/or cleaning the bandswitch with
something like Deoxit. The other possible problem could
be loose connection or cold solder joint. Would be good
if you had a scope or signal tracer to "see" where the
signal is dropping out.

Good luck and good listening

Mingram - without seeing the schematic I might hazard a
couple of guesses and possible tips. The local oscillotor
may be trying to dropout at the higher frequencies or
you may have a dirty section(s) in the bandswitch. Try
substituting the osc/mixer tube and/or cleaning the bandswitch with
something like Deoxit. The other possible problem could
be loose connection or cold solder joint. Would be good
if you had a scope or signal tracer to "see" where the
signal is dropping out.

Good luck and good listening

Mingram - without seeing the schematic I might hazard a
couple of guesses and possible tips. The local oscillotor
may be trying to dropout at the higher frequencies or
you may have a dirty section(s) in the bandswitch. Try
substituting the osc/mixer tube and/or cleaning the bandswitch with
something like Deoxit. The other possible problem could
be loose connection or cold solder joint. Would be good
if you had a scope or signal tracer to "see" where the
signal is dropping out.

Good luck and good listening

: I HAVE A PHILCO 40-155 RADIO THAT PLAYS GOOD ON BROADCAST AND POLICE BAND BUT WHEN I SWITCH TO SHORT WAVE 6-18, IT BECOMES VERY NOISY AND WILL NOT PICK UP SIGNALS. WHEN I GROUND ANTENNA TERMINAL 3 TO THE CHASSIS (WHILE LOOP ANTENNA IS STILL CONNECTED) IT PICKS UP GREAT BUT THEN WHEN I SWITCH BACK TO BROADCAST THE SIGNALS ARE VERY WEAK. (THEN I HAVE TO REMOVE THE GROUND WIRE FOR IT TO PLAY AGAIN) SCHEMATICS CAN BE FOUND IN RIDER VOLUMN 10 & 12. ANY IDEAS ON WHAT TO DO WOULD BE APPRECIATED.
: THANKS MINGRAM

Hi Mingram,
I suggest that you measure all the coils in the aerial circuit to see if any are open circuit. Also the small capacitors could be leaky or have silver migration across the mica insulation. This can cause crackling and noise. If you find an open winding, they often corrode where the wire joins the terminal and can be repaired with care. You might have to extend the end of the wire with another piece of fine wire or you might be able to unwind one turn to get extra length. Good luck, Don.