On Thu, 04 Mar 2004 19:47:59 GMT, Bruce in Alaska wrote:

In article ,
engsol wrote:

Question:

In the days of yore, did early marine radars ever use klystrons? We used them
in (very) early microwave communications systems. They were a bear to
keep on frequency, and didn't last long.

Maggies are interesting devices. If you've ever torn one apart, it mostly
looks like a machined hunk of steel, which in fact it is, and surprisingly
small.
The magnets account for most of the weight.

As to power, I recall that our airborne radar had a peak power output of
2 megaWatts, but the maggie current was only 18 - 20 milliamps. Of course
the
high voltage was 20 kV.

What kind of maggie power supply (voltage & current) is normally found in
small
marine radars these days?

Norm

Back before Gunn Diode LO's, all radars used Klystrons as Receiver LO's.
All the early Commercial Radars that came on the market after WWII used
Klystrons as receiver LO's. 2K25 comes to mind but don't hold me to
that.

Now days the radar receivers use LNA/MMIC's for FrontEnds with intergrile
solidstate LO's driving Double Balanced Active Mixers. This is why
Radars these days can see 48 and 72 miles with less than 6Kw Maggies.
Back in the bad old days it took 20 and sometimes 40Kw to see out 72
miles, because the receivers were KLystron feed Crystal Diode Mixers
with Sky High Noise Figures.

Receivers have become orders of Magnitude more sensitive than 2nd and 3rd
generation receivers of the 70's and 80's. Your Tax dollars at work.
(US MIlitary Electronics Development Dollars)

V and A for common Maggies are in the 2Kv- 3Kv range with peak currents
of an amp, and up to 2 amps PEAK. This all compes from the Pulse
Forming Network that is usually feed by a switching powersupply up in
the T/R Pan that runs on 10-40 VDC Ships Mains, or some such variation
of Power supply for the Radar. 9M502 and 9M503 come to mind for common
3-5 Kw maggies, with the old 2J42 for the 9 - 10 Kw versions. Haven't
kept up on the state of the art for the last 7 or so years, but the
basic's haven't changed all that much in the Tx side of the Antenna Pan.

Bruce in alaska
Thanks much Bruce...very helpful info. And I forgot about those diode mixers
in the rx front end. 1N34? Was that the one?
Norm