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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 17th Dec 2014, 6:56 pm   #21
G6Tanuki
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Default Re: 1-500MHz frequency counter

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Originally Posted by Bazz4CQJ View Post
I did ask the question previously on the forum about affective ways of protecting the input but don't recall any exceptional suggestions. A pair of Schottkies side by side may be a basic approach. Something more elaborate would probably be nice in terms of keeping the input impedance high.
I've got somewhere a "Cirkit DFM7" [basically a prescaler hooked to a PCIM177 counter/LCD display] and back when I was using it to align Pye Westminsters/Olympics/Pegasi on 2Mand 4M I 'protected' it by fitting a 500Ohm carbon resistor (non-inductive) between the input terminal of the prescaler and the input-socket on the case, with a pair of 1N4001 clipper-diodes in opposite directions between the prescaler-input and earth.

Given that the prescaler as-designed had about a 10mV VHF sensitivity, the extra series-resistance didn't cause any problems.

This was good-enough protection that the prescaler survived having 15 Watts of RF shoved up it on rather more than one occasion.
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Old 17th Dec 2014, 6:57 pm   #22
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Default Re: 1-500MHz frequency counter

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BNC beats this over and over again, hands down.
I agree, but for a small PCB the SMA is better. And once you start making millions of the things any saving in materials (I guess the BNC takes 4 times the metal an SMA does) is significant, tons of metal.
 
Old 17th Dec 2014, 7:11 pm   #23
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Default Re: 1-500MHz frequency counter

BNC [or for preference N] for things on the outsides-of-instruments, but fitting a BNC or a N to a modern microscopic SMD PCB is a real pain. Using SMA on-board makes sense - a short flexible lead to your connector-of-choice on the actual case means you remove connect/disconnect stresses from the PCB.
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Old 17th Dec 2014, 8:18 pm   #24
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Default Re: 1-500MHz frequency counter

The advantage of BNC is that if you try a 50ohm one into a 75 socket, no damage unlike Ns.
 
Old 18th Dec 2014, 7:08 am   #25
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Default Re: 1-500MHz frequency counter

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Originally Posted by Stockden View Post
I think it's actually "Bayonet Neill–Concelman" - see here
Silly me. You're right. Thanks for correcting common lore...

Still, had I owned test equipment with SMA sockets I'd put a BNC-F->SMA-M adapter on it. Unless it's for microwave frequencies.

Tjerk, 9ZZ
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Old 15th Oct 2015, 11:56 pm   #26
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Default Re: 1-500MHz frequency counter

I’ve revived this thread as there’s been two other threads started by different people on the same subject, and this thread has the most appropriate thread title for anyone looking for information regarding these great little frequency counters.

I always think it’s a shame that different threads get started with unrelated titles on the same pieces of kit, although this is understandable. It would be a bit of a mammoth, or even impossible task for anyone to try to edit all three threads into one complete and informative thread, so I’m going to put a link to the most recent thread, which doesn’t have a related title at the time of typing this post, although has a link back to this one, but also a link to the other thread (which does have a related title) which is in the hidden section (until a high enough post count) of the forum – complicated?

Hopefully, anyone doing a ‘search’ for information on these counters will be able to find what they want to know a bit easier now as I feel that these cheap little units are a very useful piece of kit for the vintage radio enthusiast.

Link:-

https://www.vintage-radio.net/forum/...d.php?t=120297
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