Setting 54 MHz Slug/TVI trap

[Low_Boy]

I can't figure this out , I can't even seem to find a good 54 MHz signal.
So how would someone set up a spectrum analyzer to adjust a TVI trap that has been fooled with?
Question for the more experienced.

 

[Robb]

What are you using to see the 54mhz signal - to begin with.

Don't really need to be an expert to figure this one out. If just one coil in that 54mh filter circuit has been spread; then that whole 54mhz filter circuit has gone out of tune and therefore it will leak the 54mhz harmonics thru to the radio's output.

You can use a RTL-SDR dongle and your computer to see the 54mhz 2nd harmonic. If you test the radio on - say ch 20 (which is 27.205mhz); then the second harmonic will always be found at twice that same freq. IOW - 54.410mhz, since 2 x 27.205 = 54.410 (just do the simple math). You don't need to be a rocket scientist to figure out that much - lol.

So all we need to do is to restore that filter circuit back to stock and it will filter as it should. Some radios are built with fixed trap circuits and some are adjustable. But you will need to set your radio on 27.205mhz and your RTL-SDR/computer freq to 54.410mhz to see the 2nd harmonic spike when you hit the TX key. Lowering that 54mhz spike will mean that you are making the trap circuit more effective and filtering out more goo.

The trap circuit will let ALL of the 27.205mhz signal pass thru completely intact - despite what some golden screwdriver will try to tell you. It is tuned for the 54mhz range - and nothing more. If adjusted correctly, you will see less watts coming out of the radio. This is good, since you just filtered out all of the 54mhz harmonic crap you didn't want/need anyway.

If a coil has been spread; then push it back together to its original shape. If the core of the 54mhz adjustment coil has been removed; then replace it and retune it for max filtering.

Fair place to start . . .
Be interested in what the techs will add/subtract.

 

[Low_Boy]

Thanks Robb. I still can't seem to find 54MHz on the spectrum analyzer.

 

[Captain Kilowatt]

Thanks Robb. I still can't seem to find 54MHz on the spectrum analyzer.

Where 54 MHz appears on the screen is completely relative. It depends how you have the spectrum analyzer set up. Sounds like it's time to RTFM.