On 12/01/2015 01:41 PM, Ian Field wrote:
"Michael Black" wrote in message
xample.org...
On Mon, 30 Nov 2015, Ian Field wrote:
"mike" wrote in message
...
On 11/29/2015 6:03 PM, Michael Black wrote:
On Mon, 30 Nov 2015, Cursitor Doom wrote:
On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote:
Sorry, no recommendations as all my stuff is ancient.
So's a lot of my stuff. But there's nothing wrong with old gear
IMO it's
the quality of it and whether it's in calibration that counts. The
only
issues with GDOs IME are that they're not too bad for the lower
frequency
RF stuff, but hopeless for anything higher.
Huh? VHF and UHF is where they really worked well, because at lower
frequencies, a lot of the coils were shielded. There were GDOs that
worked well at VHF and UHF.
Michael
Best one I ever used was the tube version of the Millen.
I switched to the solid state version and regretted it.
Much less sensitive and more fiddly than the tube version.
Tunnel dipper was the worst for sensitivity.
A while back I acquired a small Tektronix component envelope
containing very tiny "top hat" style diodes that there's a faint
possibility they could be TDs.
Copying the Heathkit TD dipper had crossed my mind - now I probably
won't.
It seemed like the Tunnel Diode got a lot of press in the sixties in
the hobby magazines, but much of it wsa novelty. I can't remember
anything where some other device couldn't be used.
Back then there was a fanatical craze for FM bug transmitters - with a
tunnel diode, the circuitry was always smaller than the battery.
The problem was that TDs had such a lot of capacitance that it was only
the ones with the huge peak currents (200 mA!) that were really fast.
I have a bunch of 2 mA TDs with 200 pF of capacitance. Fast? Not so much.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net