Quote:
Originally Posted by benman94
I'm currently considering a deal for a set that used a 7GP4 CRT originally, but now has a 7JP4 replacement in it. This particular model set can only produce about 3 kV EHT. Is there any issue using a 7JP4 as a substitute for a 7GP4? Has anyone here ever done this with good results?
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Hi,
The 7GP4 was really the forerunner of the new and improved 7JP4. The 7GP4 maximum anode voltage was only 4000 volts. They used this tube in some late 40's Sylvannia Oscilloscopes.
Substituting a 7JP4 for a 7GP4 should be no problem. Just don't go the other
way around, the voltages would be too high.
If you make changes to a set designed for 3 to 4 KV you may have to increase the working voltage of the high voltage capacitors. You may also have to add more resistance to the high voltage bleeder string.
Here's the data on a 7GP4:
http://frank.pocnet.net/sheets/049/7/7GP4.pdf
Ed