Part Identification for Amplifier Research 100W1000B  - Page 1
Forum section: electronics / repair

author: RamEP
author_rank: Contributor
timestamp: May 02, 2020, 01:12:09 pm
content: 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

author: CaptDon
author_rank: Super Contributor
timestamp: May 02, 2020, 05:23:32 pm
content: At first it appeared as a typical RF transistor, however looking at thepower connection on the output side through the RF chokes and noapparent 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' markingon the circuit board. If you know the frequency range of the moduleyou could look through a mini-circuits catalog to find a match. I doremember they made some similar looking devices for the radars Iused to work on. Does that 100W1000 have the insanely expensivewater cooled final amplifier tubes? An EMI test lab I deal with has a unitwith tubes you can hold in one hand that cost as much as a niceused car!!! Apparently Eimac/CPI made only a few of those tubesmostly for the military when 'cost was no object'!!! Eimac made a4CX600 series for the military, a very nice tube, but triple the priceof the bigger 4CX800, 4CX1000, 4CX1500 series, which also seemto be going extinct as the broadcast industry now has solid state devicesof the same power levels.

author: RamEP
author_rank: Contributor
timestamp: May 02, 2020, 08:18:29 pm
content: > would say it is a hybrid RF amplifier.This would also be evidenced by the 'U' marking and not a 'T' markingon the circuit board. If you know the frequency range of the moduleyou 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-$600KThanks for the help!

author: graybeard
author_rank: Frequent Contributor
timestamp: May 03, 2020, 12:41:56 am
content: It could be a GaAs part from RFMD (now Qorvo).

author: CaptDon
author_rank: Super Contributor
timestamp: May 03, 2020, 02:47:00 am
content: The little hybrids we used in low power radar looked like the oneyou have pictured. The ears on the side were ground and heatsinkingand the input side showed a 50 ohm impedance match with VSWRof less than 1.5:1 across the design frequency. You would capacitorcouple to the input exactly the way your circuit looks and D.C. powerwas fed to the output side through RF chokes exactly the way your boardlayout indicates. Because there was D.C. on the output you also hadto capacitor couple to the input of the next stage. I guess check theD.C. voltage to make sure the RF choke is not open and use a scopeto look at input signal vs output signal of that stage.

author: CaptDon
author_rank: Super Contributor
timestamp: May 03, 2020, 02:54:11 am
content: 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 unitshave N connectors in and out and I think around 20 to 30db gain with a maxpower output of maybe 5 to 10 watts.