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From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <4BDDE8D5.2060106@g3ysx.org.uk>
Date: Sun, 2 May 2010 23:44:14 +0100
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Subject: LF: Re: CMAC 12MHz TCXO
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Hi Stewart I have a C-MAC catalogue but from somewhere around 2000 it has a
lot on frequency determining components but has no model numbers like to
describe

A quick look at the numbers suggests that you have a component manufactured
in October 1994. Interestingly if you visit the C-MAC site www.cmac.com they
dont list frequency components amonst their products at all. Which suggests
they sold that part off  sometime in the last few years. All the later TCXOs
in the cat have numbers like IQTCXO-250

This makes me wonder whther they were selling International Quartz products
or whether they sold the business to them ....I haveny looked but memory
suggests International Quartz was a bit crystal etc manufacturer in the
States.....I think they advertised in QST.

Not a lot of help but you may know where to look now.

I usually use an ohm-meter on unknowns. I have been quite successful at
deriving the pin-outs. It is easiest if one pin is connected to the case.
The output is probably o/c at DC (capacitively coupled) the supply pin shows
about a few kohms to ground and the EFC pin (if it has one is high
resistance 10s or even 100s K. If you find the supply pin start by putting
5v on that (its too early for 3.3v logic) see if you can detect any out put
then rack the level up to 12 volts watching the current draw and the output.
The most difficult where some old Cathodeon units which didnt have the case
grounded. But someone came up eventually with a pin out for those.

Best Wishes
Alan G3NYK


----- Original Message ----- 
From: "Stewart Bryant" <stewart@g3ysx.org.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, May 02, 2010 10:04 PM
Subject: LF: CMAC 12MHz TCXO


> Hi,
>
> I have a couple of 12MHz TCXOs that I think must have come from the LF
> community, probably they are ex Decca. I am trying to find the pinout
> and required supply voltage, and I am hoping that someone in the group
> might be able to help.
>
> The marking on the top side says
>
> CMAC
> TXCO4 B741
> Freq 12MHz
> 9441
>
> One the bottom I see
>
>
> GND             pin
>
>                  pin
>
> pin             pin
>
> The unit is something like 30mm x 20mm x 12mm (guess by eye)
>
> Thanks for any help
>
> 73
>
> Stewart/G3YSX
>
>
>