1N23E vs. Schottkey?? Question
 

This is on a 10 gig receive setup. There is no LNFE, just antenna
to mixer direct couple in a balanced waveguide mixer assembly.
The question is, if I remove the 1N23E/1N23ER pair, and go with a
balanced set of schottkey microwave diodes, this would allow me to
drop my local oscillator injection perhaps 6db. Will I see any
increased sensativity, or should I just keep the 1N23 setup?

I am not sure, but let me know if you need any of them. I've got a partial
reel of HP dual diodes in a SOT-23 package.
They are intended for use in your application.

Pete

"gudmundur" wrote in message
...
This is on a 10 gig receive setup. There is no LNFE, just antenna
to mixer direct couple in a balanced waveguide mixer assembly.
The question is, if I remove the 1N23E/1N23ER pair, and go with a
balanced set of schottkey microwave diodes, this would allow me to
drop my local oscillator injection perhaps 6db. Will I see any
increased sensativity, or should I just keep the 1N23 setup?

gudmundur wrote:
This is on a 10 gig receive setup. There is no LNFE, just antenna
to mixer direct couple in a balanced waveguide mixer assembly.
The question is, if I remove the 1N23E/1N23ER pair, and go with a
balanced set of schottkey microwave diodes, this would allow me to
drop my local oscillator injection perhaps 6db. Will I see any
increased sensativity, or should I just keep the 1N23 setup?


wow, those 1N21/23 diodes are stone age! They are Germanium diodes
and usually have to be biased for lowest noise, best conversion
figure. Also when used in cavities, the diode itself forms part
of the coupling network. The letter in the diode part is a measure
of noise figure, the higher up in the alphabet you go, the lower
the rated noise figure. BTW those diodes a dated from the
1940's!

On Mon, 07 Mar 2005 22:16:01 -0500, Ken Scharf
wrote:

wow, those 1N21/23 diodes are stone age!

BTW those diodes a dated from the
1940's!


So am I (1937 actually) but I still work fine!! Just 'coz it's old
doesn't mean it's had it! :-)

Peter, G3PHO

Youngster - 1936 here
vk4aok

Peter wrote:

On Mon, 07 Mar 2005 22:16:01 -0500, Ken Scharf
wrote:


wow, those 1N21/23 diodes are stone age!


BTW those diodes a dated from the
1940's!



So am I (1937 actually) but I still work fine!! Just 'coz it's old
doesn't mean it's had it! :-)

Peter, G3PHO

In article ,
says...

gudmundur wrote:
This is on a 10 gig receive setup. There is no LNFE, just antenna
to mixer direct couple in a balanced waveguide mixer assembly.
The question is, if I remove the 1N23E/1N23ER pair, and go with a
balanced set of schottkey microwave diodes, this would allow me to
drop my local oscillator injection perhaps 6db. Will I see any
increased sensativity, or should I just keep the 1N23 setup?


wow, those 1N21/23 diodes are stone age! They are Germanium diodes
and usually have to be biased for lowest noise, best conversion
figure. Also when used in cavities, the diode itself forms part
of the coupling network. The letter in the diode part is a measure
of noise figure, the higher up in the alphabet you go, the lower
the rated noise figure. BTW those diodes a dated from the
1940's!

Yes, they were used in WWII radars with 2K25 klystron locals,
and we call that generation 1, in the late 70's they quit using
ATR/TR tubes on the lower power stuff, and went with circulators
and diode limiters, but the 1N23E/R remained firmly rooted in these
gen 2 radars until the late eighties. Gen 3 brought about the LNFE/MMIC
front end with a double balanced mixer featuring I/Q phase rejection
in the mixer stage producing I.F. output only when the local osc is
above the incoming signal. These front ends have about 6db gain over
the broadband 1N23 setup, and are much quieter, giving about a 10db
better SNR overall. So now the little Gen3 2.2kw units see targets that
the old 4kw units never could!

Yes this is some older stuff I have, a mid eighties radar front end
with a 10gig hamband gunn local, now back to our regularly scheduled
question, Should I buy $70 worth of matched schottkey, or $40 worth
of 1N23EMR. I have to buy something, my old crystals are way shot!!

On Mon, 07 Mar 2005 22:16:01 -0500, Ken Scharf
wrote:

gudmundur wrote:
This is on a 10 gig receive setup. There is no LNFE, just antenna
to mixer direct couple in a balanced waveguide mixer assembly.
The question is, if I remove the 1N23E/1N23ER pair, and go with a
balanced set of schottkey microwave diodes, this would allow me to
drop my local oscillator injection perhaps 6db. Will I see any
increased sensativity, or should I just keep the 1N23 setup?


wow, those 1N21/23 diodes are stone age! They are Germanium diodes
and usually have to be biased for lowest noise, best conversion
figure. Also when used in cavities, the diode itself forms part
of the coupling network. The letter in the diode part is a measure
of noise figure, the higher up in the alphabet you go, the lower
the rated noise figure. BTW those diodes a dated from the
1940's!

when the devices were too old, they couldn't use them, and called them
1N451(?), and had modern diodes for another 50 years


---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm

Peter wrote:
On Mon, 07 Mar 2005 22:16:01 -0500, Ken Scharf
wrote:


wow, those 1N21/23 diodes are stone age!


BTW those diodes a dated from the
1940's!



So am I (1937 actually) but I still work fine!! Just 'coz it's old
doesn't mean it's had it! :-)

Peter, G3PHO
Never meant to infer that old stuff doesn't work (and sometimes well)
after all some of the guys on this NG also frequent the antique radio
NG. I wasn't aware that the 1n21/23 series diodes were considered
state of the art until the late 70's/early 80's though. Actually
in the 60's many hams used PAR-AMPS (which are a kind of MASER!)
in front of their diode mixers. (I remember an article in QST from
the 60's on a reflex klyston pumped par-amp using an early
varicap diode).

I'm the youngster -- 1938.

Seems that I'm in the right circle of 'Old Farts' to ask: Has anyone a
data sheet available on the 723A/B Reflex Klystron? These (along with
the 1N21 diodes) were used in the AN/APS-3 RADAR and since have found
use in physics demonstration devices, and to a limited extent ham radio
(with modifications). It is basically a 3-cm or 10-GHZ oscillator.

I have a pin-out, but not a full-blown data sheet. Can anyone help me
out on this?

Thanks in advance, and 73's.

Harry C.

p.s. Evidently a large number of 723A/Bs were produced by Raytheon, but
in spite of a 15-year employment with the Raytheon Company, I've never
been able to locate a data sheet. Evidently devices of this type were
heavily classified during WWII, and consequently most of the
documentation was classified and eventually, in accordance with
security instructions, destroyed.