With the replacement of the Schottky diodes out of the way I have been working on the LED assembly to replace the mercury cells. I've got an assembly that looks like it will work (produces 1.4-1.5 V

Now beef up the speedup capacitor and you’ll be like new. 220pF added should do. Dave Wise Sent: Wednesday, September 22, 2021 1:31 PM To: TekScopes@groups.io Subject: Re: [TekScopes] Tek 547 B

Hi there thanks for your help, Q373 was the cause , a 2n2207 had turned into two diodes according to my tester, probably a whisker inside. I replaced it with a BC556 and it worked

Roger, adjusting R2291 now brings the readout onto the crt screen. However, I had to set R2291 to an end stop. I guess I should check out possible out of spec resistors etc. It is possible that the

Yes, I plan to include that when I rebuild the circuit. Thanks, Barry - N4BUQ

Perhaps the later on added R4426 2k between Q4420 collector and GND is intended to prevent this. Albert

I have confirmed that Tek still sells these and they are in production. They are $14.95 Each board will need 5x. Part number is 131-1003-00 Zen

Barry, CR4419 is a clamp. Voltage at the emitter and one end of the 33 and 5600 ohm resistors can go lower than 15,6-15,7V, not higher. It also sets the common base voltage and current limit for the

Okay, Mark. Will do. BTW, can you explain the function of CR4419? I don't find the part of the circuit surrounding Q4420 outlined in the Circuit Description section of the manual for the Vertical

Barry, I was wrong about the 2N2222A being a sub. The original is a PNP. My mistake. The voltages would be best checked with the transistor and resistors replaced. Testing the output IC from the

Neat! Well, if it's not visible, it won't do any harm. I'd guess most is hidden in the trace blanking time anyway. Try and find a TG501 and don't forget to terminate into 50 Ohm or you'll think it

Hi Raymond, I had some of the round two fin tophat style sinks and after filing flats on a side of each can fit pairs onto the outputs. I also was concerned about possible capacitive coupling

Hi Mark, Okay on the parts. Apparently I was searching for a 2N4152 for CR4419 instead of a 1N4152 (which is readily available). Is it acceptable to check the voltages at the IC without Q4420

In this video I saw a quick glimpse of a 567 with a 6R1 built right into a PDP-4 computer. https://youtu.be/sPU8-fkaRWc?t=530 That's pretty cool.

Would it not be more informative to say: 3 photos uploaded relative to a tek 5A20N ? Thanks larry

I bought Chinese ones when I restored my scope. They compensate fine. It seems there is only one big manufacturer and a million people selling the same thing. At the price they ask you can buy 2 or 3

Hello Ron, thank you for your kind words. I have curve-traced the JFETs for their standard output characteristics, i.e. Id vs. Vds, and best similarity of the ohmic, say the linear region and best

Tektronix sell the Peltola connectors. David

Magnus, Great work, thanks for sharing. Which parameters were used to match the JFETs? How close were the parameter readings to get an OK match? Regards, Ron -

S/N B0303xx 492BP The production date seems to be around 1989 or so, can someone confirm that? I am looking to buy one but it would be nice to know if there were no surface mount caps in it.