[time-nuts] Re: HP 10509A antenna specifications?

[Bob Camp]

Hi

The antenna was a loop antenna. Designing one is non-trivial, but there is a lot
of info out on the internet. The one thing you do *not* want is a chunk of conduit
around the outside of the antenna. 

How many turns, what resonating capacitor, what sort of preamp in the antenna …..
very much a “that depends” sort of thing. (… the original antenna had a preamp in it …).

The bigger issue is the basic fact they have changed the WWVB signal format. 
The new “phase modulation” approach plays havoc with the traditional test gear.
It pretty much makes it un-usable. 

Bob

> On Feb 28, 2023, at 3:40 PM, Matt Krick via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> I am refurbishing a HP117A VLF comparator and would like to recreate the
> outdoor antenna.
> 
> I've cleaned up the A1 module where all of the 4.0uF at 60V caps leaked
> electrolyte damaging the wiring and ate holes in the ground plane on the
> PCB.
> 
> I've also made most of the updates to bring the unit up to serial prefix
> 832 from a 512. Can't seem to find a human part number for the 1853-0009
> transistors though.
> 
> I've also got new Nuvistors coming for module A1.
> 
> So far my ferrite stick antenna doesn't have enough signal strength to make
> the meter twitch. But using a function generator it takes about a -80dBm to
> get the signal strength meter to come to the 10 mark.
> 
> For the antenna It looks like the outer structure is just conduit and a
> couple of junction boxes but I would like to know if anyone has more
> detailed specifications of the loops inside the conduit. Such as number of
> turns and gauge of wire that was used in the original.
> 
> Thank you!
> --Matt
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