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National Company S-Meters
Hello-
I have a small qty. of NOS National Company S-meters from an old CB shop. I can furnish a JPEG on request, should have a few extra to sell. Can someone help me in using these meters : The pointer resides at full scale, rather than at the low scale as most meters. I guess you would say the meter pointer is "backwards", however the meter scale is normal { not "backwards"}. How would you compensate for this in S-meter circuit? Thanks, Byron, WA5THJ |
Is it a NC57 Tuning Meter??? as shown at
http://www.io.com/~nielw/nat_list/SM57.HTM Lionel VK4NS Byron Tatum wrote: Hello- I have a small qty. of NOS National Company S-meters from an old CB shop. I can furnish a JPEG on request, should have a few extra to sell. Can someone help me in using these meters : The pointer resides at full scale, rather than at the low scale as most meters. I guess you would say the meter pointer is "backwards", however the meter scale is normal { not "backwards"}. How would you compensate for this in S-meter circuit? Thanks, Byron, WA5THJ |
Is it a NC57 Tuning Meter??? as shown at
http://www.io.com/~nielw/nat_list/SM57.HTM Lionel VK4NS Byron Tatum wrote: Hello- I have a small qty. of NOS National Company S-meters from an old CB shop. I can furnish a JPEG on request, should have a few extra to sell. Can someone help me in using these meters : The pointer resides at full scale, rather than at the low scale as most meters. I guess you would say the meter pointer is "backwards", however the meter scale is normal { not "backwards"}. How would you compensate for this in S-meter circuit? Thanks, Byron, WA5THJ |
The pointer resides at full scale, rather than at the low scale as most meters. I guess you would say the meter pointer is "backwards", however the meter scale is normal { not "backwards"}. How would you compensate for this in S-meter circuit? If the meter simply reads the plate current of an RF, mixer, or IF tube controlled by the AGC, then the stronger the signal, the less current, so the meter needle will move right as the signal increases. Almost every RX S-meter works off the tube current, but uses a resisotr bridge to make the meter see *more* current as the signal decreases the plate current. Just to muddy up the discussion, most classic Panasonic "canoe anchor" SW portables have their S-meters actually read backwards -- strong signal pushes the needle left! Whose idea that was, I'll never know, but the Japanese do drive on the wrong side of the road (so why don't Racal sets read backwards too :-) -- Mike K. Oscar loves trash, but hates Spam! Delete him to reply to me. |
The pointer resides at full scale, rather than at the low scale as most meters. I guess you would say the meter pointer is "backwards", however the meter scale is normal { not "backwards"}. How would you compensate for this in S-meter circuit? If the meter simply reads the plate current of an RF, mixer, or IF tube controlled by the AGC, then the stronger the signal, the less current, so the meter needle will move right as the signal increases. Almost every RX S-meter works off the tube current, but uses a resisotr bridge to make the meter see *more* current as the signal decreases the plate current. Just to muddy up the discussion, most classic Panasonic "canoe anchor" SW portables have their S-meters actually read backwards -- strong signal pushes the needle left! Whose idea that was, I'll never know, but the Japanese do drive on the wrong side of the road (so why don't Racal sets read backwards too :-) -- Mike K. Oscar loves trash, but hates Spam! Delete him to reply to me. |
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