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Tricky Schematics

P

paws264

Active Member
Apr 6, 2005
646
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While attempting to help a guy out with his amp, I went to that Tricky CB site and looked up the electrical road map for the amp in question.

kenny1971 said:
SANY8110.jpg
Can someone help me with info on this part pointed out in the photo ?? Put too much into the amp and burned this part.
Click to expand...

I found this schematic:

cb.jpg


It is mistakenly drawn and cannot be used, it should be corrected. there are two mistakes on the drawing, one where the high voltage is ties to ground and another mistake where the tank coil for the driver section has been completely deleted. Compare this drawing to the re-drawn .PDF file.

tricky1.jpg


I wonder how many more drawings there are like this and, will they be corrected any time soon?

.
 
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It's a coil. And the rest of the amp looks a little old and nasty too. Any roaches come crawling out when you took the cover off?
2mpe5id.gif
 
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Are we talking about L6? It's a plate choke and not a very good one at that from the looks of it. Plate chokes are not critical as to value as long as they have enough inductance at the lowest freq of operation. Get a piece of ferrite bar from an old AM radio,cover it with some insulating tape, and wind it completely from end to end with small wire and the job is done.Tell him next time to take it easy on the input drive.
 
QRN said:
Are we talking about L6? It's a plate choke and not a very good one at that from the looks of it. Plate chokes are not critical as to value as long as they have enough inductance at the lowest freq of operation. Get a piece of ferrite bar from an old AM radio,cover it with some insulating tape, and wind it completely from end to end with small wire and the job is done.Tell him next time to take it easy on the input drive.
Click to expand...


All very good 'cept for one thing, in my experience, it has been good engineering practice to use Teflon or some other highly resistive material (Bakelite) as the form to wind your High Voltage Plate Choke on.

If, we look at the diagram, you will see that there are no dotted lines associated with the B+ Choke indicating that there is not a magnetic core involved.

If, you are constructing / repairing a Bifilar Cathode Choke for directly heated Triode tubes then, by all means, a ferrous core is required but not for the plate circuit.

.
 
hitman said:
Does anyone know what the choke on the bottom left hand side is in this pic.?
Click to expand...

22uH. It is a protection device for if C11, the .005 uF cap would happen to short there would be high voltage going to the antenna. With the choke being there it would short the high voltage power supply to ground and hopefully R11, the 2 ohm 10 W wirewound resistor would open up, killing the high voltage.
 

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