Waveguide Repair

With no information on sizes and material it is difficult to say, Boss. So I'll set the ball rolling with a can opener and a pop rivet gun. Owzat?

Is there a prize for getting it right?

There is a prize Stenson. A genuine British prize bar.

Don't forget the gold plated waveduct tape.

Depending.on the frequency they are mostly not repairable.

Any scratched or warped.interal surfaces will degrade the performance. Reflected energy is not good.

They should be replaced.

It is unlikely that the waveguide itself is damaged beyond useful repair. Waveguide is nothing more than precision pipes. Often bad waveguide is replaced instead of repaired. If the internal cavities were exposed to smoke damage then careful internal cleaning to get any soot out of the cavity before it can be possibly reused. Once the waveguide path ways have been reconfigured there maybe a need to perform the RF black magic of dent tuning the waveguide.

Much more critical is when the waveguide was damaged, it could have taken out many very expensive, long lead time components:

• Power amplifiers (traveling wave or klystron tube amplifiers)
• Low noise amplifier
• Magic T
• RF power isolator
• Waveguide filters (both pass and time equalising)

I used to be around some rather interesting characters. One of them claimed to have done 120 GHz work before 120 GHz existed (wink). He claimed that he was provided with a huge tool box that was nothing more than calibrated ball bearings, calibrated magnets and a very wide assortment of calibrated hammers. He claimed he would tune up a system by dropping in a ball bearing and moving it around with a magnet on the outside of the wave guide tube. Based upon his knowledge of black magic he would then decide to either leave it in place, roll it out and replace it with a different size ball bearing or use a precision hammer to make a precision dent. He might do this for days before he was happy.

I suspect that everything was machined down to the thousandth's of an inch. Using a hammer to make the system work properly seemed so silly that it probably was true.

All this was done while wearing a pointed purple hat with big white dots on it. They wouldn't let him wave his wand around or sprinkle pixie dust.

Radio astronomy work in the 120 GHZ range was performed before 1984? Would you prefer a citation from 1974 instead.

Heat could warp the metal.

I have no idea what actually happened at the cite, so my response is simply for academic interest.

Whatever happened, the damage must be extensive. Might even involve phased array multiplexing and no wave guides.

Oh well. Weigh them in for scrap and get new ones. That is what is involved.

What is involved in repairing damage to waveguides?

Bringing them back to nominal print dimensions and performance qualifiers.

We are talking FAA here, it is very unlikely they used anything much above 20 - 25 ghz, likely much lower....what i would do is check the S-parameters before and after the repair, and decide if the degradation in performance due to the repair is acceptable compared to the cost of replacement.