I'm interested in how the signal tracer works? I've tinkered with the eico 145 on a Philco radio before but noticed in the earlier tube stages I hear a buzzing noise,when checking different points(plate) on the tubes then when testing tubes closer to the speaker I could hear the actual radio station (music),So my question is whats the signal suppose sound like in the earlier tubes?Thanks,Mike

If you are checking prior to the detector stage, you may only get buzzing. You will need to use a detector probe prior to the detector stage in the radio. I hope this helps.

MRO

:I'm interested in how the signal tracer works? I've tinkered with the eico 145 on a Philco radio before but noticed in the earlier tube stages I hear a buzzing noise,when checking different points(plate) on the tubes then when testing tubes closer to the speaker I could hear the actual radio station (music),So my question is whats the signal suppose sound like in the earlier tubes?Thanks,Mike

There is a very good Signal Tracing tutorial right on this site...

http://www.nostalgiaair.org/References/Articles/post/index.htm

Mike, one of the short comings of a signal tracer, in order to trace a signal you need a know signal. Usually you input a modulated RF signal (RF signal with a 400kc AF rider). The hum you will hear is the 400kc. Now you apply the signal say to the antenna of the set under test and work your way to the speaker. If the radio is working and you have a distorted signal that you want to isolate you can work back from speaker to find where distortion begins, but there you have the signal to trace. Without a known signal being put in, you are hearing hum from anything that in the air near your probe. PL

:There is a very good Signal Tracing tutorial right on this site...
:
:http://www.nostalgiaair.org/References/Articles/post/index.htm

PL,
Shouldn't that be RF plus 400Hz AF rider
(AM modulation) vs 400kc AF rider.

marv

: Mike, one of the short comings of a signal tracer, in order to trace a signal you need a know signal. Usually you input a modulated RF signal (RF signal with a 400kc AF rider). The hum you will hear is the 400kc. Now you apply the signal say to the antenna of the set under test and work your way to the speaker. If the radio is working and you have a distorted signal that you want to isolate you can work back from speaker to find where distortion begins, but there you have the signal to trace. Without a known signal being put in, you are hearing hum from anything that in the air near your probe. PL
:
:
::There is a very good Signal Tracing tutorial right on this site...
::
::http://www.nostalgiaair.org/References/Articles/post/index.htm

Marv, yes, I stand corrected.

:PL,
:Shouldn't that be RF plus 400Hz AF rider
:(AM modulation) vs 400kc AF rider.
:
:marv
:
:: Mike, one of the short comings of a signal tracer, in order to trace a signal you need a know signal. Usually you input a modulated RF signal (RF signal with a 400kc AF rider). The hum you will hear is the 400kc. Now you apply the signal say to the antenna of the set under test and work your way to the speaker. If the radio is working and you have a distorted signal that you want to isolate you can work back from speaker to find where distortion begins, but there you have the signal to trace. Without a known signal being put in, you are hearing hum from anything that in the air near your probe. PL
::
::
:::There is a very good Signal Tracing tutorial right on this site...
:::
:::http://www.nostalgiaair.org/References/Articles/post/index.htm

Thanks,for everybody's help and I've checked out the article on this site its really helpful,so my next question is to do a signal input is that done with a signal generator? Sorry,I've been been doing the replacing caps,resistors & tubes in old radios the basic stuff, so I've been picking up test equipment lately to advance my knowledge more,so I'm not very electronic educated but learning as I go.