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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 2nd Feb 2021, 5:47 pm   #41
Radio Wrangler
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Default Re: 'Special installation for (Bristol) Blenheim aircraft' - lash-up of test oscillat

Maybe a little test detector, built tiny for low stray L, into a DC meter. Use a Schottky diode.

Proving flatness once you get up in frequency becomes, um, interesting.

I cheat. I have microwave power meters to 40GHz and a spectrum analyser to 22GHz, but that may be getting a lot more serious than you'd want to do for fun. (That analyser goes to 110 GHz with external mixers) proving these instruments and having a traceability path to national standards labs is also, um, interesting. Just rigging something up at home that will give a reasonable indication to a few hundred MHz takes you a fair way down the path.

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Old 2nd Feb 2021, 6:11 pm   #42
Al (astral highway)
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Default Re: 'Special installation for (Bristol) Blenheim aircraft' - lash-up of test oscillat

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Originally Posted by Radio Wrangler View Post
Maybe a little test detector, built tiny for low stray L, into a DC meter. Use a Schottky diode.
Hi David, I had a similar thought! I have a crystal diode pulled from a UHF+ mixer, so I could build it around that. It's gold-plated so perhaps I should offer it in the audiophoolery community?

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Proving flatness once you get up in frequency becomes, um, interesting.
As I'm finding out! It must be amazing to have the kit that you have and know how to operate it

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Originally Posted by Radio Wrangler View Post
Just rigging something up at home that will give a reasonable indication to a few hundred MHz takes you a fair way down the path.
That would be very handy. I'm up for some lecher line experiments at the frequencies higher than this little test oscillator and perhaps up to 1GHz if as a challenge. At the very least, I will learn more about test equipment.

In my last major project, that was the area where I had the most frustration and the most learning, pushing the boundaries of my test equipment, knowing when a reading was spurious and then deciding what else I could do about it.
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Old 2nd Feb 2021, 9:13 pm   #43
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Default Re: 'Special installation for (Bristol) Blenheim aircraft' - lash-up of test oscillat

The classic uni lab setup for teaching waveguide and lecher stuff used an AM'd oscillator as the RF source, and you used a diode detector into an audio millivoltmeter to compare levels in different places.

David
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