Hickok 660
 

I just won a Hickok 660 on Ebay for $50 shipped, which I felt was a decent price.

http://www.ebay.com/itm/Hickok-660-W...vip=true&rt=nc

But I can tell by the photos that it's missing the 2 crystals it's supposed to come with, any chance someone out there has the correct ones? They are 315 kc and 3.57954 mc (normal 3.58mc subcarrier minus one horizontal line=3.563795mc).

Also hoping to win a 656XC, not sure why I'm collecting pattern gens lately. Probably a natural extension of collecting vintage color sets, I suppose. :thmbsp:

Got the manual, still need the crystals. Any help?

Pic included for reference.

http://www.videokarma.org/attachment...6&d=1393090614

Found the 315kc crystal in the other gen had broken internally, but I think I have it repaired now.

So what's the secret with these things, are they just more finicky than other brands? It's completely recapped now, and no matter what I do I can't get it working. I have the 315kc/15,750 oscillators working and sync'd up, but the closest I can get is horizontal lines only. No matter what I do, it will not display a crosshatch. Any ideas?

I NEED AN ADULT!

OK, I have a feeling the problems lie in the first crystal controlled oscillator. As a test, I clipped one lead of capacitor C6 which should isolate the 315khz crystal controlled oscillator from its accompanying 315khz blocking oscillator. But for some reason, pot R12 still varies the frequency of the crystal controlled oscillator! WTF?!? I really don't understand this, they aren't even connected to each other at this point and it's still not working correctly. I'm completely lost... :thumbsdn:

http://videokarma.org/attachment.php...8&d=1394321051

I may be off base, but here's my guess:

The crystal oscillator is 315kHz (20 times Horizontal) but the blocking oscillator is 31.5 kHz (2 x horizontal). Is that correct?

I don't see how R12 can affect the crystal oscillator, so did you have your probe on the wrong pin?

Yes, I think so. I may have made a typo earlier, the crystal one is 315khz the blocking oscillator is 31.5khz. Probe is on the correct pins, only thing I can think of is the tube is getting internal interference from one side to the other. Perhaps I should disconnect the plate supply from the 31.5 blocking oscillator and test the theory?

Weird. Does the oscillation cease when the crystal is removed?

Ditto on this question. If the oscillator can be pulled, maybe it means the crystal is dead, so take it out to see if it's doing anything.

That's the thing, the crystal wasn't having much effect at all in or out. I just remembered that my RCA WR-64B has a 189khz crystal in it, so I swapped it in and the thing came alive! Wrong frequency albeit, but it does appear that the crystal was bad after all. Now has a nice sine output from the crystal oscillator, so I still need an unobtanium 315khz crystal...

How about installing a CMOS 555 timer to drive the grid, so the first stage becomes just an amplifier? You could run it off a battery, or maybe even from a little current bled from a convenient cathode somewhere, or a large resistor and a zener off B+. You would need a trim pot to get the exact frequency, though. A more accurate option would be a higher frequency crystal and frequency divider.

Just throwing out ideas because it's easy for me to say!

Check with International Crystal Manufacturing Company in Oklahoma City. 1-800-322-9426. They might make you a crystal if you have a circuit schematic or a good part number.

Try this site, he has lots of crystals listed, I didn't see a 315KHz in his listings but he might have something in his stock.

AF4K.com

Also Surplus Sales of Nebraska has a 3.15MHz crystal for $4 and you could add a CD4017 divide by "N" IC connected for divide by 10 and get your 315KHz.

Chuck

Sent an email to AF4K, let's see what happens.

Like Old_TV_Nut said: "I'm just throwing out ideas because it's easy for me to say"...

Mouser lists a 153.6 KHz crystal (520-ECS-153-12.5-13X) for $0.76. In that circuit, which really wants very badly to oscillate already, it'll probably run fine at the 2nd harmonic (307.2 KHz). If the current doesn't kill the crystal (it's one of those little wrist-watch crystals, never tried one in a tube circuit.)

But, you'd have to figure out a way to "pull" it closer to 315 KHz (maybe buy a few and see if any are "close enough").

Hey, if it doesn't work, you're only out a couple bucks and think of all the fun you're having!

On the off chance it does work, you could disassemble the bad crystal and install the mini crystal in it's housing for a "factory" appearance.

Easy for me to say! LOL.

More irresponsible speculation: I might disassemble the bad crystal first and see if it can be repaired. Sometimes the connection between the "fingers" and the "slab" (like those terms? I just made 'em up) just needs some attention.