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8625A (8753x) Source amplifier

Question asked by johnb on Jun 13, 2011
Latest reply on Nov 19, 2011 by DavidSudry
Hi Group,

I have an HP8625A Synthesized sweeper on my bench with a damaged source. I have been able to find very little information on the 8625A but I have realized that it is really the source section from an 8753x.
The symptoms that I have are:

1) Low ouput
2) Distorted Output
3) Lots of harmonics.

I have traced the problem to the four-stage amplifier in the source module. I confirmed this by swapping the amplifier hybrid with a known good one.

I am considering designing a replacement amplier on a small board using MMICs, rather than buying a spare from eBay.

I have deduced the following specifications:

I need 0.3 to 3GHz of bandwidth
I need around 20dBm  at the 1dB compression ( minimum)
I found an earlier post where some one had indicated a measured gain of around 40dB.

I have identified the three connections

It looks like there is a supply for stage 1 thru 3

A supply for the output stage

Maybe a bias supply for the output stage?

Does anybody know the voltages on these supplies?
Many thanks

John Barnes  

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