Part Identification for Amplifier Research 100W1000B

[RamEP]

Hello, I am currently working to fix a 100W1000B and I was able to isolate the problem down to the preamplifier/leveler unit (pictured).  RF signal is coming in from the right of the screen.    I used a RF probe and believe the unit circled in red may not be functioning.  I was wondering if someone knows the part it could be.   I believe its by Mini-Circut since U6 and U7 are by them.  The marking on the part is "08" and the diameter of the body is 0.07275".  Anyone have any idea what part it is?  Thanks

[CaptDon]

At first it appeared as a typical RF transistor, however looking at the
power connection on the output side through the RF chokes and no
apparent biasing on the input side I would say it is a hybrid RF amplifier.
This would also be evidenced by the 'U' marking and not a 'T' marking
on the circuit board. If you know the frequency range of the module
you could look through a mini-circuits catalog to find a match. I do
remember they made some similar looking devices for the radars I
used to work on. Does that 100W1000 have the insanely expensive
water cooled final amplifier tubes? An EMI test lab I deal with has a unit
with tubes you can hold in one hand that cost as much as a nice
used car!!! Apparently Eimac/CPI made only a few of those tubes
mostly for the military when 'cost was no object'!!! Eimac made a
4CX600 series for the military, a very nice tube, but triple the price
of the bigger 4CX800, 4CX1000, 4CX1500 series, which also seem
to be going extinct as the broadcast industry now has solid state devices
of the same power levels.

[RamEP]

>  would say it is a hybrid RF amplifier.
This would also be evidenced by the 'U' marking and not a 'T' marking
on the circuit board. If you know the frequency range of the module
you could look through a mini-circuits catalog to find a match.

Ah thanks for the recommendation, I'll do that.  I did Google search the mini-circuits site for searches similar to "marking 08" and can't seem to find it.  Maybe the part if obsolete and newer part has different marking.  The amp covers I think 1MHz to 1Ghz, so I'd assume the parts should be that range a min if not a bit more.

> Does that 100W1000 have the insanely expensive water cooled final amplifier tubes? 

It is not have a amplifier tube, its solidstate.

> An EMI test lab I deal with has a unit with tubes you can hold in one hand that cost as much as a nice used car!!!

Wow!  That's pretty nice.  I do have another Amplifier Research,  1500T2G8A which is  2.5GHz-7.5GHz which has 4x Teledyne TWT, I think one tube is dead however I've not gotten time start trying to figure that one out.  New ones are like $500K-$600K

Thanks for the help!

[graybeard]

It could be a GaAs part from RFMD (now Qorvo). 

[CaptDon]

The little hybrids we used in low power radar looked like the one
you have pictured. The ears on the side were ground and heatsinking
and the input side showed a 50 ohm impedance match with VSWR
of less than 1.5:1 across the design frequency. You would capacitor
couple to the input exactly the way your circuit looks and D.C. power
was fed to the output side through RF chokes exactly the way your board
layout indicates. Because there was D.C. on the output you also had
to capacitor couple to the input of the next stage. I guess check the
D.C. voltage to make sure the RF choke is not open and use a scope
to look at input signal vs output signal of that stage.

[CaptDon]

Use to be able to buy the HP traveling wave amplifiers (With a good TWT)
at the hamfests for $100 to $200. They were cold war Vietnam era surplus.
The EMI lab that we use has 3 they bought surplus. I think they were 1g-2g,
2g-4g, and 4g-8g. The replacement TWT tubes today (when you can find them)
sell for about 10 times the surplus cost of the whole amplifier!! All 3 units
have N connectors in and out and I think around 20 to 30db gain with a max
power output of maybe 5 to 10 watts.