[time-nuts] HP-117A and MSF ?

paul swed paulswedb at gmail.com
Wed May 13 21:20:05 UTC 2015


Iain
The 117 would have worked for msf at 60 KHz and lucky you to have
operational loran still.
MSF as far as I know is not using any bpsk signals and i think at the top
of the minute there was a carrier drop. Not off but a reduction. So that
can cause the 117 an issue in tracking. But yes I used to use the 117 on
msf and wwvb. On the east coast of the US at night funny things would
happen between the 2 signals.

The 30 V you reference was intended for a nuvistor preamp at the antenna.
This is easily replaced with 2n3904 transistors as an example. Or the real
loop antenna if you actually have it.

Now the fact that you have LORAN timing receivers perhaps is a real benefit
as the phase changes you see from the 117 will represent the propagation
behaviors. That used to be fun to watch. But we messed all that up in the
US.
Regards
Paul
WB8TSL


On Wed, May 13, 2015 at 2:40 PM, Iain Young <iain at g7iii.net> wrote:

> Hi All,
>
> Has anyone considered using (or even used) a HP 117A for receiving and/
> or measuring MSF ? I had one of those mad idea evenings last night after
> comparing MSF to the Greenwich Time Signal for a few days (More info on
> my next post...)
>
> But back to the mad idea, I thought I might use a 117A to:
>
>    o compare MSF against my three LORAN boxes (Yes the 1Meg would need to
> be divided down...)
>    o Use the Signal Level 1/4" stereo phone jack and a resistor to feed
> a time decoder, for yet another clock, just to help justify having the
> 117 [and to compare my SDR decoders to of course...] :)
>
> The potential issues I thought of (so far) are:
>
>    o 50Hz vs 60Hz power. Not really a big issue, I can get converters
> to solve this one.
>
>    o Being a TRF receiver, and with me only having an LF whip with
> pre-amp, I'd need to add filtering, but again not the end of the world.
>
>    o 30V on the antenna line. Seems that I may be able to use the test
> connector. Alternatively, a Bias Tee, or just cutting the DC supply to
> the antenna connector should suffice, I can't believe it would be that
> hard
>
>   o MSF off time. Now this might be a bit more of a problem for phase
> measurements, MSF doesn't just reduce the carrier like WWVB and DCF, but
> drops it entirely.
>
>     Anyone know if this would "just" give me interruptions to the
> comparisons, during the 100-300 msec off times, or would it entirely
> mess up the comparison with the "house standard" ?
>
>     I'm guessing it would depend on if MSF just cuts the carrier from
> the output stages or if they stop the actual carrier generation...
>
> Any other issues I might run into other than the usual aging issues and
> so forth ?
>
>
> Iain
>
>
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