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The CB Forum => CB Radio Repair Forum => Topic started by: KC4UMO on March 25, 2004, 09:03:30 AM

Title: Service monitor
Post by: KC4UMO on March 25, 2004, 09:03:30 AM

Since the early 80 I have thought about taking a cobra radio and converting it to a servive monitor. Not sure which cobra to use but any should work fine. I have looked at the B&K and they are too expensive for my taste.
Anyone have any thoughts on this:

Title: Service monitor
Post by: KC4UMO on October 12, 2004, 09:06:08 AM

Well, I am using a cobr radio to tune and lign other radios. Sort of crude but works. Now if I could just add some features

Title: Service Monitor
Post by: Invisible_2_no1 on October 28, 2004, 08:26:15 AM

I would like to se this modification. I dont think it would be hard to convert a cobra into a full serviice monitor.  You should be able to ass features like 400, 1000 hz tone to it also. You can also pull the 455kz straight to an output jack.

Just an idea.

Title: Re: Service monitor
Post by: The Radio Shop on February 05, 2012, 09:34:30 AM

Now this brings back memories

Title: Re: Service monitor
Post by: hackindave on February 06, 2012, 08:16:41 PM

The "monitor" system you are building in a computer case has had my head running ever since I saw it. I want to make something similar. I also want to add a 350 watt computer power supply to it. It should give me about a 30 amp supply. The good part about it, it will also give me a 5volt line, and I am going to pull a 12volt line and make a circuit to make it variable from about 3 volts up. I have about 4 29GTL classics that I am going to use in it. I can make a signal generator with it and put a line in for the 455 signal out of it. I will have a speaker hooked to the 29 so I can hear what ever radio I am working on.  I thought about putting a ssb radio in it so I can check ssb. I pulled my old Browning LTD out the other day, but really don't want to "trash" the LTD. Think I will head over to E-Bay and find a cheap 40 channel ssb radio I can put in it. Probably a Realistic as I don't have use for most of their radios...

When I get going on it, I will post some pictures

Title: Re: Service monitor
Post by: The Radio Shop on February 06, 2012, 09:32:58 PM

Hey that sounds great. A realistic should make a fine unit.  I have to get back on mine. Just so busy latley hard to do it. But makes me feel good knowing that others are following it.

I like the 5 volt line also. Thought about making it varible to supply voltage to nonworking stages of the unit under test. Another thing I want to design is an frequency error meter.  +/- 5 kc analog type. I have that in my expensive IRF and would love to have it in the homebrew rig.

Title: Re: Service monitor
Post by: hackindave on February 07, 2012, 03:10:51 PM

I got to thinking more about it last night. Some other things that could be added. I will have the 5 volt variable in it also, but I am also going to add a salt water dummy load to it. This way it can all be home brew and no oils to mess with. I think you could almost build just about everything you need inside a computer case, except a scope.

http://www.qsl.net/k5lxp/projects/SaltLoad/SaltLoad.html

Title: Re: Service monitor
Post by: The Radio Shop on February 27, 2012, 03:29:47 PM

tone generator

Title: Re: Service monitor
Post by: hackindave on March 05, 2012, 05:50:27 AM

Is this a stable tone?

Title: Re: Service monitor
Post by: 577-Jersey on March 05, 2012, 08:27:54 AM

Hopping aboard guys,,
 I have an empty puter chassis out in the shop and would like to build a nice service monitor out of it also.
 Great ideas here!!!

577

Title: Re: Service monitor
Post by: The Radio Shop on March 05, 2012, 09:05:29 AM

Good deal Tommy. Keep us posted on results :)

Dave. The 555 tone generator is stable, but nasty. So we have to clean it up a bit.