Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- 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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Garey Barrell Verzonden: zondag 20 februari 2005 17:47 Aan: Mike Williams CC: Drakelist Onderwerp: Re: [drakelist] DR-7 Display
Garey Barrell <[EMAIL PROTECTED]> 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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