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 Post subject: What are these testers?
PostPosted: May Tue 15, 2018 11:54 pm 
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Joined: Mar Sat 01, 2008 10:02 pm
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Location: Mission British Columbia
I got 2 similar testers among a trunk load of ham stuff. They look like home brews. Both have a 1.5 v battery as well as a 4x9v
= 36v battery supply installed.
What would these have tested. I took them to a ham swap meet and couldn't find anyone who knew either?

Frank


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 Post subject: Re: What are these testers?
PostPosted: May Wed 16, 2018 12:15 am 
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Can you post photos of the insides? They look kind of hand made, although pretty professionally done. I could take some wild guesses from the dials, but let's see the guts first

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 Post subject: Re: What are these testers?
PostPosted: May Wed 16, 2018 12:25 am 
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I see a couple of LH0052CH FET op amps. 2 boards in this set.
Frank


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 Post subject: Re: What are these testers?
PostPosted: May Wed 16, 2018 12:36 am 
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Thanks. Yes, those are home built devices. Pretty nice job of it too. Wild guess, without a lot of study, is that these were built by a Ham Radio operator as signal quality monitors. Hope that helps ... if your question was what are they worth? I'm afraid not much unless someone wants some of the parts in there.

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 Post subject: Re: What are these testers?
PostPosted: May Wed 16, 2018 2:50 am 
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Joined: Nov Mon 02, 2009 7:01 am
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Location: Lincoln City, OR
Greetings to fvan and the Forum:

We used similar gear in broadcasting. Commercially produced, of course. We called them "Modulation Monitors". The "% Deviation" and "FE" (Frequency Error) display how far off the assigned carrier frequency you are. The "Monitor" meters are recovered audio level meters.... and may be calibrated in % modulation. The red dots on the monitor meters probably represent the maximum permitted modulation for some particular system. For FM broadcast, this would be 75KHz peak deviation. For BTSC stereo in the NTSC system, it would be 25 KHz peak deviation. For really old FM communication systems, it would be 15 KHz peak deviation. For more modern systems, it would be 5 KHz peak deviation. And of course, for AM, it represents 100% modulation.

Regards,

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 Post subject: Re: What are these testers?
PostPosted: May Thu 17, 2018 12:00 pm 
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Location: Long Island
They appear to be home-made monitoring panels for frequency and deviation meters--perhaps from a test set-up that would have been used by a two-way radio shop. You'll note that there are only DC amplifiers and low frequency circuitry on the boards, and banana jacks on the panels. No RF components or connectors. So they must've been used with some other piece of equipment like an FM modulator or a communications monitor that processed the RF and provided the frequency reference. That other equipment may have been a commercial device or perhaps it was also "home-brew."

Parts value aside, there isn't a whole lot one can do with stuff like this, especially if the other equipment it was meant to be used with is no longer around.

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 Post subject: Re: What are these testers?
PostPosted: May Thu 17, 2018 1:09 pm 
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Sad in those type of estates when the equipment is in one place, and the paperwork/documentation etc. is in another and no one thinks to match any of it up. "Throw those old papers away!" So now you have a pile of parts, there. Meters, multiturn pots and dials, and switches and jacks maybe, worth saving. Rest is rubbish. Sad as it looks well made for whatever the purpose is.

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