Electronics > Repair
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:
--- Quote from: coppercone2 on January 04, 2025, 05:53:54 am ---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?
--- End quote ---
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:
--- Quote from: MathWizard on January 04, 2025, 05:44:25 am ---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.
--- End quote ---
Sorry don't know HPAC.
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