Hp 70911A option 005 (300MHz Amp)

[K9DTV]

My 70911A started reporting errors the other day and tracked it down to the option 005 FM board.

The 300MHz amp on the board takes in a 300 MHz signal at 0 DBm and outputs at 0 DBm. But mine is outputting at -20 DBm.
These boards use 4-pin RF transistors and I have no idea what the part number is, can anyone help?

Thanks

Jim

P.s. I say transistor but know it's an IC Amp something like a MAR-4+, but have no idea.

[MathWizard]

For something that old, I'd email HPAK and ask them if any details on it, and if they recommend any modern replacements. But who/what/where in HPAC would get you results, IDK.

[coppercone2]

I think it might be somewhat safe to put a amp in there so long you determine pinout and VCC



But are you saying the circuit is unity gain?

So that there is a unity gain MMIC in there, or there is a attenuator after it to bring it back to unity? Or typo?

[K9DTV]

I think it might be somewhat safe to put a amp in there so long you determine pinout and VCC



But are you saying the circuit is unity gain?

So that there is a unity gain MMIC in there, or there is a attenuator after it to bring it back to unity? Or typo?

The 300 Mhz is used else where so it would be at least 3dbm down, so the amp would have 3dbm gaain, but this is a guess as it could be going many places.

[K9DTV]

For something that old, I'd email HPAK and ask them if any details on it, and if they recommend any modern replacements. But who/what/where in HPAC would get you results, IDK.

Sorry don't know HPAC.

[K9DTV]

Got to thinking that they would use this part in other modules and I have the Clip to the 70900b. so I took a looked.
Sure enough found the follow part. 1826-1953 and said it was made by HP (28480) but more checking found it was made by Avantec inc and it's a msa-0335.
More checking shows that HP bought Avantec inc and this maybe a MAR-3SM.

http://www.hp.woodshot.com/hprfhelp/4_downld/products/rfics/msa0335.pdf