On Mon, 30 Nov 2015 19:05:02 -0500, Michael Black
wrote:
It seemed like the Tunnel Diode got a lot of press in the sixties in the
hobby magazines, but much of it wsa novelty.
For good reason. Tunnel diodes flew in most of the early satellites
up to about 1990 because it was the only reliable microwave device
available at the time.
I can't remember anything
where some other device couldn't be used. I suppose when the Heathkit GDO
came out, the Tunnel Diode might have had better bandwidth, though I don't
remember that GDO has having great VHF and UHF coverage. But while neat
things were shown, that tunnel diode FM broadcast receiver was more unique
becuase of the low IF and pulse counting detector than that it used a
tunnel diode as a mixer/oscillator down to that low IF.
I believe you're referring to the HW-10 GDO:
http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/
http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/HM-10A.gif
No pulse counting detector but rather a simple half wave RF rectifier
followed by 3 stages of DC amplification. As I vaguely recall, I had
difficulties getting a clean dip because the tunnel diode was probably
oscillating on multiple frequencies at the same time.
I may have an HW-10 GDO somewhere in my junk pile. I dropped it from
about 60ft up during an antenna raising party. It landed in some
bushes and did not appear to be damaged, but failed to function
afterwards. I also have a few new TEK tunnel diodes.
There were uses for tunnel diodes that hobbyists generally didn't see, and
those at least took advantage of the device at the time, but the time
passed pretty fast before other things didn't do most of what a tunnel
diode could do.
Tektronix also used tunnel diodes in their oscilloscope trigger
circuitry:
http://w140.com/tekwiki/wiki/Tunnel_diodes
I use one testing scope rise time:
https://richardsears.wordpress.com/2013/04/27/tunnel-diode-pulser/
GE Tunnel Diode Manual (1961):
http://w140.com/Ge1961TunnelDiodeManual.pdf
Today, Aeroflex/Cobham/Metelics currently sell tunnel diode detectors
and use them in their instruments:
http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MTD.cfm
http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MBD.cfm
Sorry, but tunnel diodes are not quite dead and obsolete.
So I think the Heathkit tunnel diode dipper was mostly for novelty sake.
Nope. During the 1960's, the big draw for Heathkit was that kits were
much cheaper than labor intensive assembled products. Heathkit had to
do something to keep the price down on their products. Cheap was the
order of the day and tunnel diodes were CHEEEEEEP.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558