[time-nuts] Tracor 527A and 10MHz reference input

paul swed paulswedb at gmail.com
Sun Jun 25 15:36:16 EDT 2017


Dave will guess you are sub sampling the 10 Mhz ref.
Yes it should be 4.7K. Not sure why but old military gear resistors were
like that. Circa 1942 at least in schematics I have seen.
Regards
Paul
WB8TSL

On Sun, Jun 25, 2017 at 2:25 PM, David C. Partridge <
david.partridge at perdrix.co.uk> wrote:

> Yes, does indeed look like it should be 4K7!
>
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of David C.
> Partridge
> Sent: 25 June 2017 18:50
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] Tracor 527A and 10MHz reference input
>
> A friend says his Tracor 527A works fine with a 10MHz Ref input even
> though it doesn't have the divide by 2 circuit from the addendum to the
> 527E manual applied.
>
> I'm puzzled by this - I can't quite see how the reference input circuit
> can produce a 5MHz output when fed with 10MHz (unless his reference source
> has a large 5MHz sub-harmonic).
>
> Am I missing something here?
>
> On a related note, the schematic for the divide by 2 circuit in the front
> of the 527E manual shows a 4R7 resistor from the base of the 2N3904 to
> ground - this just feels all wrong!!  Has anyone built this and did they
> change the resistor to (e.g. 47R or 4K7)?
>
> Thanks
> Dave
>
>
>
>
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