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48-475 signal injection
Patrick
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#6

09-29-2015, 08:54 PM
(09-29-2015, 07:53 PM)Raleigh Wrote:  Are you injecting your signal through a .1 uF cap?  If not capacitively isolated, any DC on your Sig Gen lead could change the grid bias.

But don't ask me why the same thing doesn't happen at point "D".  It's a mystery to me.

Everything I've found on line says that the 7C5 is an acceptable substitute for the 7B5 & the specs look similar enough.

Yes, I'm using a .1 uf cap.

Here's the troubleshooting sheet I'm using. All voltages are good. C201 and C203 are both new. R202 is within tolerance. There is also no audio output when injecting a signal at test point "A" either. 

Even though the voltages checked out O.K. on pin 2 and pin 3 of the 7C5, could there be a problem with it? I should have just stuck in another tube. 

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Messages In This Thread
48-475 signal injection - by Patrick - 09-27-2015, 02:34 PM
RE: 48-475 signal injection - by Patrick - 09-29-2015, 02:47 PM
RE: 48-475 signal injection - by Radioroslyn - 09-29-2015, 06:11 PM
RE: 48-475 signal injection - by Patrick - 09-29-2015, 06:41 PM
RE: 48-475 signal injection - by Raleigh - 09-29-2015, 07:53 PM
RE: 48-475 signal injection - by Patrick - 09-29-2015, 08:54 PM
RE: 48-475 signal injection - by Raleigh - 10-02-2015, 10:27 PM
RE: 48-475 signal injection - by Patrick - 10-04-2015, 01:00 AM
RE: 48-475 signal injection - by Patrick - 10-09-2015, 02:44 PM
RE: 48-475 signal injection - by Patrick - 10-09-2015, 01:23 PM



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