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

[Matt Krick]

I do have some MC1596s So I'm playing with the idea of making a card for
the spare card slot in the back to double and then divide by 2 with a
transistor flip flop similar to the other cards in the unit do.

On Tue, Feb 28, 2023, 15:21 paul swed <paulswedb at gmail.com> wrote:

> Great to hear on the vlf117 Matt.
> I have 2 of the units that I had to repair also. Fortunately no leaking
> caps.
> The urge is to add new tubes and then tweak the coils. Don't. They are
> fragile.
> However the fact that you need -80 dbm does seem a bit low.
> Assuming the preamp in the antenna is about 10 db or so.
> Believe there were 2 antenna versions. One used 2 X nuvistors and as I
> recall the other 2 X transistors.
> Coax sends 30 VDC.
> The antenna is a loop antenna and does look like a piece of conduit. But
> there is a break in the conduit so it
> does not form a shorted turn. Typically the loop is a piece of 25 pair
> phone cable. The ends solder together turn by turn to make 1 wire.
> Then a resonating cap for 60 KHz.
>
> Now the bad news.
> Even if you get the vlf117 working. It can no longer track the wwvb
> carrier because phase shift keying was introduced some 10 years ago. This
> obsoletes all of the old tracking receivers. You need some adapter to get
> rid of the keying.
> Several have been made. One thats been very effective is the d-psk-r.
> Search time nuts archives. But these adapters are a whole additional layer
> of complexity.
> Without them you have a nice heater.
> Good luck Matt.
> Paul
> WB8TSL
>
>
>
> On Tue, Feb 28, 2023 at 5:48 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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>