[FoxHunt] PIN diodes anyone?

[Dale Hunt WB6BYU]

There is a section on the HomingIn website where Joe discusses PIN
diodes.  Try this:

http://www.homingin.com/Sources.html

and scroll down to PIN diodes.

You might also read his notes on the HANDI-finder set - it is very
similar in design to the DoubleDuckie.


Personally I'd just use 1N4148 switching diodes in the circuit,
even though I have a stash of PIN diodes around somewhere.
I'd focus on other changes instead: a 555 timer rather than the
567 PLL for the oscillator (just because they are more common)
and some sort of phase detector circuit so the box tells me
RIGHT/LEFT rather than trying to find a bi-directional null.
The circuitry is a bit more complicated, but not difficult.  There
are a number of circuits available on the web.  Here is one:

http://home.att.net/~jleggio/projects/rdf/tdoa1.htm

and I'm sure you can find many more with a search on "TDOA".

You'll find a huge increase in functionality between such a
device and the DDDF-type with bi-directional nulls.

Good luck!

- Dale WB6BYU



On 28 Jun 2008, at 06:59, Barry Fox wrote:

I am thinking of building a "Double-Duckie" as seen on page 14-17 of the
15th Edition (1988) of the ARRL Antenna Manual.  So far I have been
unable to find a source of the PIN diodes, HP #5082-3077.  Anyone out
there build one of these and have a couple of spares or know of a 
source?
Or at least a very good substitute?  The handbook seems to prefer the HP
over other choices in the article.  A search of the usual vendors 
yielded
no luck, no doubt since a lot of diodes have come and gone since 1988.

BTW, I hide a "foxbox" in the north central MA area most weekends, but
not this one as we are all involved in Field Day.  Anyone in the area
or passing through is welcome to seek it out and sign the log.
Go to:  http://home.comcast.net/~foxbw/  for latest info.  For the next
several weeks it will be hidden in various spots in the Cowdrey Nature
Preserve off Rte 2A in Lunenburg, MA.
Thanks for any help on the diodes,
73,
Barry - W1HFN
Sterling, MA














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