[Elecraft] 1N4007 diode question?

Mon Apr 7 23:29:01 2003

I've used a great many silicon diodes as RF switches. That use goes way =
back
before PIN diodes. All one needs is sufficient bias to keep the diode =
either
conducting or not conducting, as you desire.=20

Isn't the unique feature of a PIN diode its ability to act as a variable
resistor to RF as the bias is varied, rather than rectifying he RF? That
capability isn't used in a simple T/R switch like, say, in the KPA100.=20

I just did a quick check and came up with the "CQ Antenna Roundup" book
published in 1963 (FORTY years ago!) in which Don Stoner, W6TNS and L.A.
Earnshaw, ZL1AAX describe the use of silicon diodes as RF switches with
examples in a variety of applications. They were using early silicon =
power
rectifiers in this application.

Ron AC7AC
K2 # 1289

-----Original Message-----
From: [email protected] =
[mailto:[email protected]]
On Behalf Of Don Brown

...My curiosity got me to thinking so an experiment was in order. I went =
out
and bread boarded a circuit. It looks like the entire family of 1n4000
exhibit the PIN characteristics. I tried the 1n4001, 1n4002 and 1n4007 =
at
different frequencies from 3 to 40 mHz at 5 volts Pk to Pk and they all =
work
the same with a switching current of about 8 ma. Just for grins I tried =
a
1n4148 and it does not work at all. It rectifies the RF as you would =
expect.
The 1n4007 passes the RF without distorting it at all.

There are several articles on the web that mention that the 1n4007 is =
the
only one in the series that will work as a PIN diode but my tests seem =
to
discount that. So will a 1n4005 diode work in place of the 1n4007 in the =
K2
possibly, but I would still go back and use the proper part if possible.

Don Brown
KD5NDB