Help identifying mysterious component in RF power amp

Thread Starter


Joined Oct 24, 2016
Dear folks,

I have a broken 75watt Rf power amplifier and I can't figure out what these components are. I have marked them on red circles on the attached picture. It may be related with this circuit having a fast blanking feature (to stop any signal from being amplified). I also can't find any info on the component marked on pink, which has the reference ¨1f13aj fqb 27p06¨. In case it helps, the amplifier is a class AB meant for 1 MHz-100 MHz range.

I would appreciate any help identifying any of these components, as that could take me closer to understand how this thing works, either to fox it or to learn from it.



Joined Jan 27, 2019
The red circled components are resistors, as in this example circuit: tb250.pdf
I can't find a schematic from their examples that matches this one for the SR401 but you can search here maybe you'll have more luck.


Joined Mar 10, 2019
Agree those in red are non-inductive resistors. The pink thing may be a voltage regulator for bias supply, else some kind of transistor/MOSFET driver device. One would need the part number from that to be sure...

Thread Starter


Joined Oct 24, 2016
Thank you very much for the replies, wayneh, Yaakov and sagor. Low inductance resistors... I would have never guessed. Knowing that they are resistors will help me a lot trying to figure out the workings of this amp.

@Yaakov, your link to schematics from the manufacturer is very handy. I will go though them to see if there is any similar one.

I don't know why google gave me no results (literally zero results) on the pink component yesterday, because today I could find that the 'FQB27P06' is a MOSFET, as sagor was guessing.

Again, thank you very much folks!