From: Garey Barrell 
Subject: Re: [drakelist] DR-7 Display


Garey Barrell  made an utterence to the drakelist gang
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Dick -

I hope I'm wrong, but it looks like the HEF4xxx series is the equivalent 
to the MC4xxx series CMOS, not the ECL line.

I can't find any data on a HEF 40138, but if you can, see if it is a 
"Bi-quinary Counter" or three RS flip-flops.  I suspect it's
something else.

73, Garey - K4OAH
Atlanta

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



Dick Harms PA2DW wrote:

>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
>----------------------------------------------------------------------
>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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