Spectrum Analyzer suitability for CB radios

[okrobie]

sorry, I didn't tell you what the picture is. It was using the sampler I described through the antenna coax switch into a BNC scope probe, with the mic button pushed and no modulation or tones.

[Bobcat]

Okay, I have one more question about your attempt to get a display......

If you look at the 2nd analyzer display that I sent you.... the one with the "bump" showing...
If you look above and to the right you see a little display window with "14.5" showing in it.
THAT was my Center setting for the analyzer. That setting tells the SA what frequency I want to "center" on
so IT makes the center-most vertical line on the screen be (in my case) 14.5 Mhz. I was actually somewhere in the 14.2 Mhz area... so I was a little to the left of it...but it DID show up on the screen.

Now to YOUR picture....

I see a box in the upper right that appears to say Center Frequency but all I can see in it is a "-" and a "0".

Did you indeed have your "center frequency" set on the SA?
For instance, if you were going to try on Channel 19... you would want your center frequency set for as close
to 27.185 Mhz as you can get it. That way the screen will "zero in" on the content in that area of the spectrum.
If that is not set right.... all you may see is harmonic "hash" of some kind...and that is what that display looks like.

SO I am double checking.... did you have "center frequency" set somewhere NEAR the channel you were using to test?

Thanks!
Bob

[okrobie]

Hey Bob, sorry I haven’t been able to text for a minute. I decided that my Avcom wasn’t working so I exercised my opinion to return it to the seller. But by coincidence there was another SA on Facebook Marketplace here locally. It is a Tektronix 491. I took a freq meter and an RF sig gen with me to make sure it was working. It wasn’t. I couldn’t get the signal to show on the screen so I made the guy a $50 as-is offer and he took it. There is much more technical support out there for this model than the Avcom so I should be able to fix it. (I hope). I’ll get it on the bench soon and keep you updated as I progress. 73, Jim

[okrobie]

BTW, I’m taking the gamble that it has a blown front end and that I’ll be able to fix it.

[Bobcat]

Okrobie, you can tell me to shut up ANY time you want!!!!!!

I just went out and found a Maintenance Manual on the Tek 491 made by Tektronix for the US Army.
I tried to attach it... but the limit is just a hair over 9Mb for a PDF file upload.

If you need it.... maybe I can email it to you or something....

[okrobie]

Hey Bob, I’ll never tell you to shut up. We’re brothers of a different mother.😎

Where did you find this manual? Maybe I could download it directly from the same site you did.

It sure sounds like what I need.

73

[Bobcat]

Here is the link I got it from . Up at the top is a GREEN Download button.... start there....

I am not sure how full it is...but there seems to be a lot in it. I hope it does you some good.

Bob

https://www.manualslib.com/manual/48...ronix-491.html

[okrobie]

Thanks Bob, that's quite a manual. If I can't fix it with that, it can't be fixed, Thanks, Jim

[Bobcat]

You are welcome! I hope that it helps you get to a fully functional Spectrum Analyzer!

[okrobie]

Manual or no manual. The first thing I’m going to do is open it up and look for smoke. I’m as sure as I can be that someone has hooked this thing up to an 80 meter 5KW flame thrower and I’ll see a smoky mass on the other side of the BNC input connector. Wish me well.😎