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 Post subject: Knight-Kit KG-687 Sweep Generator
PostPosted: Aug Mon 09, 2004 10:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 342
Location: Fremont, CA, USA
I'm attempting a repair of the subject generator. Among other things, I have found a dead SPS-4103 transistor. I can't identify a replacement for it. It is the only transistor in the unit that isn't a SPS-3908, so something must be special about it. It looks like a Motorola marking on all the transistors. I'm guessing that the SPS-3908 is a special Motorola package of the 2N3908, which might make the SPS-4103 a 2N4103. I can't find any data on that number either.<P>Anybody have any experience with these sweepers? Is it worth fixing? I'm getting discouraged, and I'm about ready to toss it. The tuning capacitor plates are so closely spaced that the Marker capacitor was shorting, and it took a careful adjustment of the bearing to fix it, but I'm not encouraged that the fix is going to last. <P>Thanks<P>------------------<BR>


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 Post subject: Knight-Kit KG-687 Sweep Generator
PostPosted: Aug Mon 09, 2004 5:39 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 30701
Location: Livermore, CA
Hi Ken<P> SPS3908 is replaceable by ECG 123A.<P> ECG 123A listed as silicon, NPN, BVcbo = 75, BVceo = 40, Ic = .8 amps, Ft = 300MHz, hFE = 200 typ, TO-18 package. Nothing really unusual.<P>------------------<BR>Norm


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 Post subject: Knight-Kit KG-687 Sweep Generator
PostPosted: Aug Mon 09, 2004 7:18 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 342
Location: Fremont, CA, USA
Actually, I did find that reference for the SPS-3908, but it is the SPS-4103 that has me stumped. It may be the same as a 2N4103, and I'm tracking that down. I have conflicting information as to whether that is a transistor or an SCR. For some reason, they decided that the sps-3908 that they used for everything else, including the Marker VFO, was not good enough for the sweep oscillator. The spec for the SPS-4103 must be unique in some way. <P>------------------<BR>


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 Post subject: Re: Knight-Kit KG-687 Sweep Generator
PostPosted: Oct Sun 25, 2020 8:18 pm 
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Joined: Oct Sun 25, 2020 12:47 pm
Posts: 1
Hello,

I know this is an old thread but I was wondering if someone figured this out by any chance?
The transistor 'TR4' on the schematics of the Knight KG-684 sweep-marker generator and also in the service manual is marked as ' NPN (SPS-4103) '
The numbers written on the transistor are '0142' and 'M952' with M clearly the Motorola label.
The transistor is of the TO-92 type and for sure an NPN. At the backside a coloured striping is visible: gold-brown.
I'm interested in the specifications so I could figure out a replacement.
I checked all the old books I could find, but nowhere any reference to SPS-4103 or 0142 / M 952 ...

Kind Regards,

Jan


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