Protect Your Amplifier Modules with RF Pre-Amp Protection

[dnyberg2]

I have these great Mini-Circuits amplifier modules (ZFL-1000LN+) I use all the time that keep getting blown by a nearby HAM radio operator. Can I protect the input to this module by soldering two anti-parallel fast switching diodes from the input connection to ground?

 

[Averagesupernova]

I doubt that you are frying this thing from a nearby ham. You realize that hams would use this sort of device on their own receivers which would have to take much more when it is next to the transmitter than in your situation. Unless you are the ham, you are not closer than that. It takes over 2 milliwatts to do it according to specs. You sure it isn't ESD or something? What's the application? Diodes right out on an antenna is a bad idea concerning generating more interference.

 

[berkeman]

I have these great Mini-Circuits amplifier modules (ZFL-1000LN+) I use all the time that keep getting blown by a nearby HAM radio operator. Can I protect the input to this module by soldering two anti-parallel fast switching diodes from the input connection to ground?

What frequencies are you using in your setup? What is connected to the input and output of your amp? Do you know what band the HAM is transmitting on, and what power they are transmitting?

 

[berkeman]

Also, minicircuits does have some limiting and protection circuits available, and also has a nice application note about protecting your preamp...

http://www.minicircuits.com/homepage/googlesearch_new.html?q=input+protection&x=0&y=0

 

[sophiecentaur]

You could always put a good RF choke in your power supply lead and/or your signal input.
Good decoupling on your power rails could also help.
I you know who he/she is, you could tell him he's almost certainly breaking the regs.

 

[Averagesupernova]

You could always put a good RF choke in your power supply lead and/or your signal input.
Good decoupling on your power rails could also help.
I you know who he/she is, you could tell him he's almost certainly breaking the regs.

By what evidence? All we know is there is a ham in the neighborhood, and some guy has mixers amplifiers failing.

 

[sophiecentaur]

That's a far too reasonable atitude! Why not sow a bit of discord when the opportunity arises?
Of course, the 'interference' would not be continuous from a Ham - just in bursts :"CQ DX CQ DX!" and the like.
A log of the times of interference would soon prove or disprove the theory.

 

[Averagesupernova]

That's a far too reasonable atitude! Why not sow a bit of discord when the opportunity arises?
Of course, the 'interference' would not be continuous from a Ham - just in bursts :"CQ DX CQ DX!" and the like.
A log of the times of interference would soon prove or disprove the theory.

Correct! We don't know what band this amp is working in nor do we know if there is any selectivity ahead of it. I.E., an antenna that is tuned to the proper band. Hard to believe front end overload would fry an amp with this spec.

 

[sophiecentaur]

If that happened to me, I'd put it down to 'cock up rather than conspiracy'.
'Frying' a component sounds like wiring it up wrong. That's always a possibility (with me, at least).