From: "Dick Harms PA2DW" 
Subject: RE: [drakelist] DR-7 Display


"Dick Harms PA2DW"  made an utterence to
the drakelist gang
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Mike, I do think that the HEF series equals the motorola MC-line. In that
case a HEF-40138 should fit and these can be bought in many stores. If you
cannot find any, I dont mind to have a go here for you!

73, Dick/PA2DW

-----Oorspronkelijk bericht-----
Van: owner-drakelist{at}www.zerobeat.net
[mailto:owner-drakelist{at}www.zerobeat.net]Namens Garey Barrell
Verzonden: zondag 20 februari 2005 17:47
Aan: Mike Williams
CC: Drakelist
Onderwerp: Re: [drakelist] DR-7 Display



Garey Barrell  made an utterence to the drakelist gang
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Mike -

These are Motorola ECL IC's.  They have been considered obsolete for
years, and short of finding one in a junkbox somewhere, very difficult
to come by.   The "parts brokers" have thousands, but they only want to
_sell_  in thousands also!

You might try reflowing the solder, since sometimes a cracked
through-hole or solder joint will present this way.

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
http://hr99.home.mindspring.com/R-4C_Servicez/>



Mike Williams wrote:

> Thanks to all who offered advice on the digital display on my TR7
> which was ( is) going bonkers.  The problem was that after an hour of
> warm up the display would start to display random digits  very
> rapidly.  The radio was still on frequency.  To complicate matters, I
> tried the counter function with a wire in the back of
> the ext  counter connector and switch set to EXT. for the external
> counter function.  Sometime the counter display worked properly with a
> 144 MHz signal input and sometimes not.  Tested dc voltages and tried
> to signal trace but my scope's bandwidth prevented any solid
> measurements.  Finally isolated the problem down to U9013 on the DR7
> board by blasting it with freeze mist; repeated this test numerous
> times with the same results.  Looks like a thermal intermittent.  Here
> is the question;  anyone know where I  can find this chip?  MC 10138 P
> is stamped on the top of the case and the Drake parts list just calls
> it a 10138.  I have searched a few electronics sites with no avail.
>
>
> Thanks much,
>
> Mike W4DL

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On Behalf of "Dick Harms PA2DW" 
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