[time-nuts] Identify RFTGM-II-XO Part

Dan Kemppainen dan at irtelemetrics.com
Wed Jan 10 12:22:50 EST 2018


Patrick,

It's possible that's one of the integrated RF amps, and not just an RF 
transistor.

You should be able to tell by tracing out the circuit. The inputs and 
outputs will typically be capacitor coupled, with DC fed to the output 
through a chip inductor or similar choke and resistor. There are some 
other variations, but that's a pretty common style part.

Here's and example. Although I doubt this is exactly what you have.
https://www.minicircuits.com/pdfs/ERA-1+.pdf
If it's one of these style amp's, you may be able to find a compatible 
part if you know the rough gain required and frequency of operation.

It appears there is a mini circuits part close by, possibly tied into 
this amp. Can you tell what part of the circuit this board covers? GPS 
signal, etc?

Dan


On 1/10/2018 1:26 AM, time-nuts-request at febo.com wrote:
> Message: 3
> Date: Tue, 9 Jan 2018 23:33:33 -0600
> From: Patrick Murphy<fgdhrtey at gmail.com>
> To:time-nuts at febo.com
> Subject: [time-nuts] Identify RFTGM-II-XO Part
> Message-ID:
> 	<CAG1UqTg3dkjunSiOc=hrkxv7untygMKPT6XqSrfm9qMdwSD2DQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
> 
> My recently purchased RFTGm-II-XO threw a fault today. When I opened it,
> the unmistakable smell of something way too hot was released. I guess this
> is one bad aspect of the totally sealed enclosures these come in. Anyway,
> when I plugged it in while open, I found U105, the microwave transistor
> about centered in the attached photo was getting way too hot. It appears to
> be an unmarked microwave transistor, probably part of the 15MHz output
> circuit. VR101 - a 7815 on the far right is also getting pretty hot. I
> expect the two are connected.
> 
> Anyone have an idea of what the nomenclature for U105 is? Replacing it may
> be a pipe dream, but knowing its name will be a good first step.
> 
> Thanks for any assist.
> 
> -Pat
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