Caution re: Collins gear and relay racks

Discussion in 'Amplitude Modulation' started by K4KYV, Oct 3, 2019.

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  1. K4KYV

    K4KYV Premium Subscriber QRZ Page

    A repurposed steel rack panel removed from a 1940-era Gates studio line amplifier holds the power supply to my push-pull mic pre-amp. It's the standard height about 3 ½ inches tall, but the vertical spacing of the screw holes doesn't exactly match that of a standard relay rack. I used a chain saw file to slightly ream out the bottom two holes, elongating them about half the diameter of the screws, to let the screws fit. It's barely visible from the front, a small gap under the screw head/washer assembly, that only someone who knows it's there would likely notice.

    I incorporated my selectable 3400~ and 6000~ passive low-pass audio filters into the line amp, which required a taller panel, liberating the original for the other purpose.

    As I recall, pre-WWII steel relay racks tend to be threaded for 10-24 screws, while later ones nearly always take 10-32s.
    N2EY likes this.
  2. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Short "desktop" 19" racks are getting to be rarer than hens' teeth...and they are SO handy. I picked up a couple dozen of these back in the 70s, that came from a pipeline control center. I quickly sold or gave away all of them to fellow hams. Wish I had kept a couple.
  3. K4KYV

    K4KYV Premium Subscriber QRZ Page

    Isn't about any long-standard item that isn't "digital" and doesn't use SMT, now getting to be rarer than hens' teeth?
    N2EY likes this.
  4. KL7AJ

    KL7AJ XML Subscriber QRZ Page

  5. KM1H

    KM1H Ham Member QRZ Page

    I use rails for all my rack mounted gear ( No 75A1) and dont bother with mounting screws.....push in; pull out.
    The rails were used on 72" high double door cabinets for early 70's era word processing gear, I got them gratis in the 80's when it was all going to scrap still wrapped up. Real heavy duty, the PS alone weighed about 75#

    Those in this area might remember the Sanders Associates 810 system which were shipped all over the US.

  6. W8KHK

    W8KHK Ham Member QRZ Page

    Yes, I recall using the Sanders Associates 700 series display terminal back circa 1975 in Miami. You triggered a few memories. The service rep often traveled to NH for training, etc. He did not much like the travel, he called it Nausea instead of Nashua. That terminal had VERY strange architecture - it did not have any display memory or character generator chip. Memory for 24x80 display was a coil of coax stuffed in the pedestal, serving as a delay line. When the data comes out, shove it back in with updates. Another thing unusual about that terminal was the method of character display. They called it a "racetrack" where the beam was deflected through all the possible 11 character segments in each character position, while the intensity was switched on and off. Similar to a 7-segment display, but with four diagonals added to create alphabetic look-alikes. We used them as a programming terminal connected to an IBM 360/50.
  7. KM1H

    KM1H Ham Member QRZ Page

    That is what we natives called it since it was such a boring city.
    I worked on the 600, 700, and 800 series starting as a tech in Chicago, advancing to district and regional support, then back to Nausea for national and international support and then into the parent company when Sanders Data Systems was sold to Harris and I told them what they could do with Dallas and TX in general:D:eek:

    Got pretty good with the IBM 360 and early 370 operators console since the 810 interfaced thru the Sanders 731 right into the Bus & Tag architecture and wrote my own diagnostics that showed up a few IBM flaws they tried to hide:p:rolleyes: Sanders lawyers sued and won a nice settlement.

    I still had my USN TS Crypto clearance in the Reserves so got involved in the Tempest program with Sanders military and special systems group and got a real education on ferrites to control Common Mode and other signal leakage issues. This was for the CIA in particular and some for the DoD. Some real interesting traveling was involved!

    This was several years before hams discovered it and I was using Fair-Rite 43 mix large beads on RG-213 and RG-11, and 75 mix large toroids on power and control leads.

    Then Sanders stumbled again and I continued RF and Tempest work for another 6 years at Wang Labs before they crashed. The old Sanders is now BAE after a few other owners and a major Nausea and NH employer.

  8. K5UJ

    K5UJ Ham Member QRZ Page

    I guess we can add filament transformers made to withstand h.v. on the secondary for gas and vacuum rectifiers to the list.
  9. WB2GCR

    WB2GCR Ham Member QRZ Page

    Go solid state for the modern version, rectification? (add slow start relay + circuit?)
  10. K5UJ

    K5UJ Ham Member QRZ Page

    Here you go:
    That's certainly an option and most fellows do that, but there's something to be said for gas rectifiers such as the xenons and I sure like the looks of the mercs. I'm going to try running 866As in my TR1 the way it was made to be run. I've always believed mercury rectifiers will work okay if a ham knows how to handle them. In some of the RCA tube manuals there are around 2 1/2 pages on how to use them. Probably the two most important points are to always keep them upright and let the filament vaporize the mercury for a good hour or so before first applying h.v. If I find a pair that have been in all sorts of positions, I let them stand upright for a long time, like a few years. The later mercs had far less mercury in them and therefore may be safer. You can see the difference between the 1940s 866As and the ones made in the 1970s. The 1940s ones are loaded. My 3-400 rig has a FWB of 3B28s. Works fine; see no reason to change.
    K4KYV and WZ5Q like this.

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