[Boatanchors] SB-303 Calibrator Part Needed

[MICHAEL TALLENT]

The MC724P was a Motorola RTL logic IC that ran on 3.6 volts, not like the 
TTL family of parts (7400 series) that ran on 5 volts.  You might be able to 
sub some 7400 series parts, but you would have to check the signal and 
loading requirements, not just the pin connections.

Mike Tallent  W6MXV
----- Original Message ----- 
From: "Walt - WB2VSJ" <wb2vsj at earthlink.net>
To: "'Boatanchor List'" <Boatanchors at mailman.qth.net>
Sent: Monday, February 15, 2010 9:44 PM
Subject: Re: [Boatanchors] SB-303 Calibrator Part Needed


> Of course NTE had to be different than TI (or vice-versa) and the other 
> DTL
> chip makers :) I'll never understand why NTE put Vcc on pin 11 and GND on
> pin 4...
>
> The NTE9924 is a quad 2 input NOR gate.  A 74LS02 or 7402 is the same in
> function but NOT in pinout.
>
> You can still find the NTE9924 on the web for $11-$15 each. Or you could
> make NTE9924 out of a 7402 by moving the pinouts around using an IC 
> socket.
> It wouldn't be pretty, but it *may* work. I do don't know about the 
> loading
> of a 7402 as compared to the NTE9924.
>
> Got an oscilloscope?  Check the signals going into and out of the NOR 
> gates
> on the 25KHz side & also check the voltages on Q602. Q602 is the 25KHz
> amplifier (I have a schematic if you need one).
>
> I'm guessing the 100KHz section works just fine?
>
> Good Luck,
>
> Walt - WB2VSJ
>
>
> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net
> [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Mark Johnson
> Sent: Monday, February 15, 2010 7:46 PM
> To: Boatanchor List
> Subject: [Boatanchors] SB-303 Calibrator Part Needed
>
> Team;
>
> I'm in need of IC-601 for the SB-303 Calibrator. This is Heath PN 443-8, 
> or
> a Motorola MC724P or NTE9924.
>
> The 25khz output is not working and I believe that my IC is shorted. 
> Anyone
> have one of these? I'll buy an entire BFO/Power Supply board from a scrap
> SB-303 if required.
>
> Thanks!
>
>
> Mark V Johnson VE3DJU/VE3DDI
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