¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
Re: Tektronix 494P 1st LO and Frequency failure(s)
P.s. test tne above with rbw well over 200kHz. That cuts out the inner yig loop which is 2/3 of the first if hw, making debugging easier.
By Edward Prest · #209620 ·
Re: Tektronix 494P 1st LO and Frequency failure(s)
no if 1st if osc...I would do in this order the following..Check... Power supplies, good, not close but right on the money. See john miles notes. Check there is any yig output , i.e.1st IF is on front
By Edward Prest · #209619 ·
Re: Tektronix 494P 1st LO and Frequency failure(s)
(Un)fortunately enough, the frequency control section is one area that I've seldom/never had to work on, myself. Since you (Federico) have extender boards, I think I'd try applying a combination of
By John Miles · #209618 ·
Re: Want : Tek576 collector knob (366-1007-00/-01) set screw hole height
Probably 0.4inch. "Common Design Parts Catalog MECHANICAL Catalog 2" helps a lot. Even the dimensions of the knob flutes are accurately described.
By Takuya Ohara · #209617 ·
Re: Tektronix 494P 1st LO and Frequency failure(s)
While it may not matter for this application, the inductance of film resistors may be different depending on type, value and trimming method both from one resistor to another as well as to carbon
By Ed Marciniak · #209616 ·
Re: Tektronix 494P 1st LO and Frequency failure(s)
Carbon composition resistors have their place where where short duration, high energy pulses are involved. Film resistors just open up. Carbon composition resistors increase in value with age,
By Glenn Little · #209615 ·
Re: Tektronix 494P 1st LO and Frequency failure(s)
FWIW Allen-Bradley carbon composition resistors are identical with Ohmite.? For some reason AB marketed through Ohmite. Same with AB and Ohmite pots.They are about the best of the carbon comp
By Richard Knoppow · #209614 ·
Re: Tektronix 494P 1st LO and Frequency failure(s)
I have repaired a 494 as well as a 2756. Apart from what KE5FX writes in his document there are a few other things to look out for. On several PCB's there are High Ohm carbon mass resistors made by
By Ulf Kylenfall · #209613 ·
Re: TEK 2465A Rebuild
Thank you! larry
By Lawrance A. Schneider · #209612 ·
Re: Tek 576 CRT specifications, design, x-rays, ... alternatives
This subject has been discussed many times over the years. A short answer is that the technical aspects of the CRT are quite modest in terms of speed (and therefore operating voltages), and the only
By ed breya · #209611 ·
Re: Tektronix 494P 1st LO and Frequency failure(s)
Hi Federico If you search the forum messages for 'John Miles' you may find some relevant information. Ciao Federico, se cerchi "John Miles" nei messaggi di questo forum, magari trovi qualche
By Roy Thistle · #209610 ·
Tektronix 494P 1st LO and Frequency failure(s)
Hi all, I'm new to this group, I'm italian, apologies for language errors ;-) I have a Tek 494P (fantastic!), but as you well know it is a ¡°time bomb¡±. I have repaired it many times, but now I am
By fedevirgo@... · #209609 ·
Re: I got a working 2465B, looking for some advice.
I didn't want to mention any particular vendor/manufacturer. Nothing? ... at least nothing inexpensive... beats the tunnel diode pulse generator, for low level, very fast, very sharp pulses. Tekwiki
By Roy Thistle · #209608 ·
Re: I got a working 2465B, looking for some advice.
If you can get the model, you can get it 3-D printed, very cheaply... maybe even free shipping. Unless you find someone locally, with a parts mule... getting the 3-print might be cheaper than shipping
By Roy Thistle · #209607 ·
Re: Want : Tek576 collector knob (366-1007-00/-01) set screw hole height
From your picture I note that we have different knob styles. I only read 366-1124-00 in the manuals 070-0905-00/01 but "Tek_RPR_366-_Knobs_and_Pushbuttons" lists both 366-1007-00/01 and 366-1124-00
By Albert Otten · #209606 ·
Re: Want : Tek576 collector knob (366-1007-00/-01) set screw hole height
Can confirm 10.16 mm (=0.4 inch) on mine /H?kan
By zenith5106 · #209605 ·
Re: Tek 576 CRT specifications, design, x-rays, ... alternatives
Another option is to increase the CRT filament voltage. The easy way is to set the mains voltage selector to LOW. Since the CRT filament is powered directly from the main power supply transformer,
By Bob Koller · #209604 ·
Re: Want : Tek576 collector knob (366-1007-00/-01) set screw hole height
at 6.8mm, I think it is too low. https://i.imgur.com/N5YSwEU.png left is the expected 10.16 mm.
By Takuya Ohara · #209603 ·
Re: Want : Tek576 collector knob (366-1007-00/-01) set screw hole height
I measured about 6.8 mm, more precise is difficult (for me). Albert
By Albert Otten · #209602 ·
Re: 7A13 overshoot
Hi Max, That was my first thought as well, having a 7A26 last year that was cursed with half a dozen bad ceramic trimmers, and last month a 492P with a bad one in the VR module. I replaced C187 with
By Adam R. Maxwell · #209601 ·