Date: Mon, 04 Oct 2010 11:53:10 -0400
From: Chuck Harris
Subject: Re: [time-nuts] 60kHz Loop antenna
The coil with 50T and 5 foot diameter is 11.5mH. It would take about
220pf of self capacitance to make it resonate at 100KHz.
Anyway, if the capacitance is too much, it's all in the wa
Understood. I have gotten better with the loops over the years.
Someone mentioned 1000 strand phone cable.
On Mon, Oct 4, 2010 at 12:52 PM, J. Forster wrote:
> 220 pF is about 8' of coax.
>
> -John
>
> =
>
> > The coil with 50T and 5 foot diameter is 11.5mH. It would take about
> >
220 pF is about 8' of coax.
-John
=
> The coil with 50T and 5 foot diameter is 11.5mH. It would take about
> 220pf
> of self capacitance to make it resonate at 100KHz.
>
> Anyway, if the capacitance is too much, it's all in the way you splice the
> ends together in the conduit box.
The coil with 50T and 5 foot diameter is 11.5mH. It would take about 220pf
of self capacitance to make it resonate at 100KHz.
Anyway, if the capacitance is too much, it's all in the way you splice the
ends together in the conduit box. If you want, you can make the loop a single
turn with 50 par
I have used 25 pair telco cable.
The issue that can happen is the inter pair and strand capacitance can
exceed the resonance frequency of the loop. Or resonates below 60 KC. Just a
heads up.
Using a 3 foot loop was not a problem.
Regards
On Mon, Oct 4, 2010 at 9:51 AM, Chuck Harris wrote:
> Aust
In message <61314.12.6.201.2.1286146064.squir...@popaccts.quikus.com>, "J. Fors
ter" writes:
>Before I got the cannonical antenna for my Austron LORAN Rx, I used a
>roughly 30" square of 3/4" Cu tubing threaded with a bunch of #18
>insulated hookup wire. The slick glop electricians use helped a lo
Austron uses an 8 conductor piece of ribbon type antenna rotor cable. They
connected all 8 strands together so the loop was a single turn. They used
a pot core transformer to help match impedance.
When I made my general purpose loop, I made an octagon shaped loop out of
3/4 inch copper pipe, an
When I designed mine maybe 20 years ago, I did consider using something
like phone cable and ribbon cable, but there was a good performance reason
for using the heavier wire. Sadly I can't recall why right now.
FWIW,
-John
===
> In message <61314.12.6.201.2.1286146064.squir...@popac
sion of precise time and frequency measurement
> Subject: Re: [time-nuts] 60kHz Loop antenna
>
>
> I observed a diurnal phase shift with my 117A system. I never investigated
> whether this was due to loop phase shifts with temperature or propagation,
> but it was like
with 'twisted pairs'?
Joe
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of J. Forster
Sent: Sunday, October 03, 2010 1:48 PM
To: b Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 60kHz Loop antenna
I observed a diurnal phase shift with my 117A system. I never investigated
whether this was due to loop phase shifts with temperature or propagation,
but it was likely a combination.
These phase shifts matter less if you are doing long term (multi-day)
measurements, but, to be valid, your system h
John,-"My concern with tuning the loop is that as the tuned circuit drifts with
temperature, or other things, an extraneous phase shift will be intoduced
to the received signal. Remember, the phase of a complex pole pair tuned
circuit goes from +90 to -90 degrees as you sweepo through resonance. T
The air core loop may well be suggested because the incremental
permeability of the ferrite, hence the inductance, varies with
temperature.
-John
=
[snip]
Interestingly a lot of the modern LF and
> VLF
> Off-air Standards use ferrite rod antennas and there are known problems
> with
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of J. Forster
> Sent: Sunday, October 03, 2010 11:29 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 60kHz Loop antenna
>
There are some interesting VLF antenna/amplifier designs on vlf.it
I used one of them as inspiration and built my own AD797 based
indoor loop antenna: http://phk.freebsd.dk/loran-c/Antenna/
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
F
VLF
Off-air Standards use ferrite rod antennas and there are known problems with
those, Quartzlock advise a air loop for critical requirements.
Alan G3NYK
- Original Message -
From: "Arthur Dent"
To:
Sent: Sunday, October 03, 2010 5:09 PM
Subject: [time-nuts] 60kHz Loop antenn
John-…”HP's loop for the 117A is not tuned, as I rember, but it
is followed with a narrow band amp.“
Both the nuvistor and FET versions of the loop show capacitors across the loop
winding to tune it.
http://www.leapsecond.com/museum/10509a/
-Arthur
___
...@febo.com] On
Behalf Of J. Forster
Sent: Sunday, October 03, 2010 11:29 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 60kHz Loop antenna
Since WWVB is a phase tracking system, I'm not convnced a high-Q loop is
such a good idea. HP's loop for the 1
ding
> doesnt
> always provide much at these frequencies and can reduce the Q of the loop.
>
> Best Wishes
> Alan G3NYK
>
> - Original Message -
> From: "Dick Moore"
> To:
> Sent: Sunday, October 03, 2010 6:56 AM
> Subject: Re: [time-nuts] 60kHz Loop
On 10/03/2010 03:33 PM, Arthur Dent wrote:
Years ago I built a modification of the double shielded WWVB loop
antenna described by Don Lancaster in a 1973 magazine.
http://www.swtpc.com/mholley/RadioElectronics/Aug1973/RE_Aug1973.htm
I have been using that same antenna ever since with good resul
Years ago I built a modification of the double shielded WWVB loop
antenna described by Don Lancaster in a 1973 magazine.
http://www.swtpc.com/mholley/RadioElectronics/Aug1973/RE_Aug1973.htm
I have been using that same antenna ever since with good results in NH
where the signal is pretty weak an
AM
Subject: Re: [time-nuts] 60kHz Loop antenna
On 10/03/2010 11:03 AM, Alan Melia wrote:
Thanks Dick, Ok with interference that close it would help. Shielding
doesnt
always provide much at these frequencies and can reduce the Q of the
loop.
I would be careful not to close the shield int
Yes Magnus, a break to avoid the shorted turn effect
Alan
- Original Message -
From: "Magnus Danielson"
To:
Sent: Sunday, October 03, 2010 10:36 AM
Subject: Re: [time-nuts] 60kHz Loop antenna
> On 10/03/2010 11:03 AM, Alan Melia wrote:
> > Thanks Dick, Ok with inte
On 10/03/2010 11:03 AM, Alan Melia wrote:
Thanks Dick, Ok with interference that close it would help. Shielding doesnt
always provide much at these frequencies and can reduce the Q of the loop.
I would be careful not to close the shield into a loop, so it only acts
on E-field and not H-field.
[time-nuts] 60kHz Loop antenna
> Alan, I did try a real half-a$$ed pile of wire and a tuning cap. My shop
has fluorescent lights and I got a lot of noise. Once I built the shielded
loop and got it lined up with east and a little south (I'm in Washington
State), WWVB came in gang-busters. This
Alan, I did try a real half-a$$ed pile of wire and a tuning cap. My shop has
fluorescent lights and I got a lot of noise. Once I built the shielded loop and
got it lined up with east and a little south (I'm in Washington State), WWVB
came in gang-busters. This was before I built a GPSDO or two a
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