Author Topic: Hp 70911A option 005 (300MHz Amp)  (Read 744 times)

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Offline K9DTVTopic starter

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Hp 70911A option 005 (300MHz Amp)
« on: January 03, 2025, 08:47:50 pm »
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.
« Last Edit: January 03, 2025, 09:05:22 pm by K9DTV »
 

Offline MathWizard

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Re: Hp 70911A option 005 (300MHz Amp)
« Reply #1 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.
 

Online coppercone2

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Re: Hp 70911A option 005 (300MHz Amp)
« Reply #2 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?
« Last Edit: January 04, 2025, 06:16:10 am by coppercone2 »
 

Offline K9DTVTopic starter

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Re: Hp 70911A option 005 (300MHz Amp)
« Reply #3 on: January 04, 2025, 07:12:44 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?

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.
 

Offline K9DTVTopic starter

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Re: Hp 70911A option 005 (300MHz Amp)
« Reply #4 on: January 04, 2025, 07:15:26 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.

Sorry don't know HPAC.
 

Offline K9DTVTopic starter

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Re: Hp 70911A option 005 (300MHz Amp)
« Reply #5 on: January 05, 2025, 04:00:19 am »
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
« Last Edit: January 05, 2025, 04:06:22 am by K9DTV »
 

Offline K9DTVTopic starter

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Re: Hp 70911A option 005 (300MHz Amp)
« Reply #6 on: January 11, 2025, 11:13:40 pm »
Got the part in and the package was way to small, so I did some more digging.
Fist the input signal is split off and used else where and the output is also split off.

The transistor was a MSA01104 this crosses out to a MAV-11SM+ that is no longer made.
But they make a MAV-11BSM+, so I ordered some, I will let the board know if it works out or not.

Thanks for everyone's input.

Jim

Added link to a cross these type of RF transistors.
https://www.hb9afo.ch/articles/MMIC/mmics.pdf
« Last Edit: January 11, 2025, 11:16:55 pm by K9DTV »
 
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Offline K9DTVTopic starter

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Re: Hp 70911A option 005 (300MHz Amp)
« Reply #7 on: January 15, 2025, 05:13:45 pm »
Parts showed up and now installed, All is well and works as it should.

Jim
 
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