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General Radio 874 Connector, inner conductor "bendies"
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Hi All:
Apologies for taking so long to respond; but, I finally found my stash of GR connectors (and a couple 500/7000 plugins using them too)¡ so I could have a look at and 874... in "the flesh" so to speak. To explain the genesis of my original "bendies" post, I saw a picture of a Tek sampling head... I though I'd like to get... and there appeared to be something odd about its 874 (...the little "barbs", I thought I saw). But as someone posted... and I can confirm by examining my 874s... the barbs I thought I saw, in the picture, were indeed an artifact of the photography, and possibly my vision. (The same is true about the picture of the 874, on Tekwiki, for what I see there, at least.) I must say, I especially enjoyed the GR articles that Dennis posted the link to. There is an article on the 874, and this is followed by another article on Variac ratings. Although I have a few General Radio pieces... maybe 10 or so... I don't recall seeing any of them using the 874... probably because they are AF, or RF units? Additionally... at least up here in the technological wilderness of Canada... few people here seem to know about, and understand an 874. I've found most of the 974 pieces I have, in bins, headed straight for the trash. Roy |
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Certainly some other vendors used GR874 125ohm connectors because their intended use was to preserve bandwidth into a 519. I remember a TRG manufactured planar photodiode with a 125 ohm connector used for monitoring laser output. One of my early mistakes was to connect the TRG diode via a GR874-BNC adaptor into a 50 ohm terminated 454 and wonder why there was no signal. I had of course connected the 50 ohm side of the adaptor to the 125 ohm TRG diode and the centre conductors do not mate. Luckily there was no damage! I am sure there must have been similar fast rise X-ray detectors but I have never actually seen one.
Roger |
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Roy Morgan
The GR 1232A Tuned Amplifier and Null Detector has an 874 connector at the input. It receives audio signals from diode mixer/detectors used in RF measurement systems that mostly had 874 connectors.
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Roy sends. On Aug 17, 2019, at 11:56 AM, Dale H. Cook <bridgewaterma@...> wrote:On 8/17/2019 11:40 AM, Roy Thistle wrote:874 connectors were pretty much universally used on GR RF instruments manufactured after 1948. |
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While it probably isn't "news" IET Labs still sells GR874 connectors along
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with other GR equipment that they still manufacture. On Sat, Aug 17, 2019 at 11:28 AM Roy Morgan <k1lky68@...> wrote:
The GR 1232A Tuned Amplifier and Null Detector has an 874 connector at the |
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On Sat, Aug 17, 2019 at 08:56 AM, Dale H. Cook wrote:
I found a 1001A that I though had a BNC output connector; but, it was an 874 to BNC adapter, inserted into the front panel 874. I have some GR units, mostly older than 1950, mostly audio, 600 ohm stuff, I guess... mostly in wooden cabinets, so old I guess too... like a 546-C, with binding posts. (sometimes seen referred to 546-0, because of the front panel stenciling?). Anyway, even though I have, and have run across GR stuff... my introduction to the 874 was on Tek stuff (like pulse gens, sample heads, and 7000 plugins)¡ which I was not interested in, at the time... so just made a note of that odd looking connector, on the front panel. I guess that was just the peculiarity of my situation... which led me to think it was an old Tek connector, when it was really GR! Best regards and wishes all. Roy |
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The General Radio part of the IEC site has many old GR catalogs. They will help identify the connectors used and those available as parts. GR used a couple of variations of binding posts, mostly combined with banana plugs or jacks. I have not checked but think the 274 type dual banana plugs and jacks had the same spacing for decades making them compatible. On many GR instruments with 874 connectors there is a combination binding post mounted under the coaxial connector. These are ground connections but a 274 dual banana plug with fit between the center part of the 874 and the binding post. This is sometimes handy where one is dealing with audio or low frequency RF although it does not have the effective shielding of the 874 connector.
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GR made adapters going to nearly anything from the 874 and both GR and others, like Pomona, made adapters of all sorts for the 274. On 8/20/2019 11:16 PM, Roy Thistle wrote:
On Sat, Aug 17, 2019 at 08:56 AM, Dale H. Cook wrote:I found a 1001A that I though had a BNC output connector; but, it was an 874 to BNC adapter, inserted into the front panel 874. --
Richard Knoppow dickburk@... WB6KBL |
Dale H. Cook
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