Re: [IRCA] TWO DX-ERS AND THE ECLIPSE

[Neil Kazaross <neilkaz58@xxxxxxxxx>]

Yes, of course, Mark. Certainly you don't want phasing errors to mess up
that great array pattern.  73 KAZ

On Sun, Jul 16, 2017 at 11:07 AM, Mark Mobile <Mark4@xxxxxxxxxxxxxxx> wrote:

> A friend reminded me that we probably should specify oxygen-depleted
> copper for the Cat 5.  We think oxygen-depleted copper is necessary for a
> uniform velocity factor in pair 3 of a copper wire cable.''
>
>
> Cheers!
>
> Mark Durenberger, mobile
>
>
> -----Original Message----- From: Neil Kazaross
> Sent: Sunday, July 16, 2017 10:20 AM
> To: Mailing list for the International Radio Club of America
> Subject: Re: [IRCA] TWO DX-ERS AND THE ECLIPSE
>
>
> No joke here, Walt. Mark got a really great deal on surplus CAT 5 in bulk
> and I've spent three weeks doing almost nothing but modelling the setup in
> EZNEC.  73 KAZ
>
> On Sat, Jul 15, 2017 at 3:13 PM, Volodya S <canswl@xxxxxxxxx> wrote:
>
> Surely this is a joke.  it's not even April.  A 2k km CAT 5 line between
>> your SDRs, and it's a mighty large Terabyte storage you have!   ;-)   Walt
>>
>> On Sat, Jul 15, 2017 at 12:02 PM, Mark Mobile <Mark4@xxxxxxxxxxxxxxx>
>> wrote:
>>
>> > There's been a lot of chatter in the Ham newsletters and the scientific
>> > community about RF-signal measurements during the August 21st eclipse.
>> But
>> > not much has appeared in the âDXâ newsletters.  In the hope of
>> stimulating
>> > an exchange about proposed listening methodologies, we want to share the
>> > eclipse-monitoring plan of two DX-ers...Nick Hall-Patch and myself.
>> >
>> > We plan to take advantage of a technology that wasn't available during
>> the
>> > last major eclipse: the Software-Defined Radio (SDR).  To give all
>> signals
>> > an equal chance, the Medium-Wave antennas used will be high-gain
>> > omni-directional.  The SDR listening posts at Nick's Victoria British
>> > Columbia home and my cabin in North-Central Minnesota will be connected
>> by
>> > a balanced wire-pair, with the separated antennas forming a
>> > Very-Long-Baseline Eclipse-Catcher Array ("VLBECA").  RF measurements
>> will
>> > be taken from 9.01 kHz through 66.666 MHz in 1.1-Hz increments.
>> >
>> > For connectivity between us to form the VLBECA, we will use pair 3
>> > (green/white) of special Cat-5 cable with pink jacketing.  (From our
>> recent
>> > desert DXPedition we found the pink outer jacket to be the best color >
>> for
>> > optimal velocity factor in the Cat-5, and we were already aware that an
>> > odd-numbered pair would maintain better polarity.)
>> >
>> > The exact distance between our two locations is 1,359.37 miles (or
>> > 2187.69395328 kilometers if you're Canadian).  Since there are a lot >
>> less
>> > miles than kilometers along the VLBECA, we chose to save money by buying
>> > the connecting cable by the mile rather than the kilometer, and that
>> meant
>> > purchasing our Cat-5 in the United States.
>> >
>> > Further input on velocity factor from the National Bureau of Standards
>> > (NBS) led us to choose stranded rather than solid wire for the Cat-5.
>> This
>> > created some contention between Nick and myself, since stranded copper
>> > is
>> > more expensive.  However, when we realized the Cat-5 route took us
>> through
>> > the Bakken Oil Fields of North Dakota, we knew the superior mechanical
>> > performance of stranded wire would provide additional integrity against
>> > rough handling.
>> >
>> > For Cat-5 pair 3 termination consistency on the two ends, we asked for
>> > bids for a pair of 2.2:1 matching transformers that would match the
>> Cat-5âs
>> > native 110-ohm impedance to the 50-ohm input of the 273 dB-gain RF
>> > amplifier.  However no one could meet our specifications.  So we ended
>> > up
>> > using the Western Electric 111C ârepeat coilâ since this device is known
>> to
>> > significantly reduce Group Delay https://www.jmu.edu/wmra-eng/
>> > archive/repeatcoil.pdf
>> >
>> > To guard against inaccuracies in the eclipse schedule, we agreed to >
>> begin
>> > recording at both monitoring stations at 0301 UTC July 27th, and to
>> > conclude at 1921 UTC, September 31st.  For the SDRs, 5600 Terabyte
>> storage
>> > devices were acquired from Best Buy.
>> >
>> > Since we will be measuring signals expected to be at the very limits of
>> > receiver noise performance, we spent a good deal of time thinking about
>> > continuous battery power since, because of possible eclipse-schedule
>> > inaccuracies, we donât want to stop the recordings during the above
>> period,
>> > lest we miss something.  Fortunately we were able to negotiate access to
>> > the battery rooms of the phone companies at our respective locations.
>> For
>> > Nick, thatâs BC Telus (formerly BC Tel; formerly the Victoria & >
>> Esquimalt
>> > Telephone Company and the New Westminster & Burrard Inlet Telephone
>> > Company) and, for me, the Upsala MN Telephone Company (formerly the
>> Upsala
>> > MN Telephone Company).  Connectivity to these battery rooms will use
>> > fabric-covered lamp cord acquired from Mark Connelly.  We believe the
>> color
>> > of the lamp cord fabric will not impact the Group Delay.
>> >
>> > Once the recordings have been made (assuming there really IS an eclipse)
>> > Nick and I will meet in Salt Lake City Saturday October 7th late >
>> afteroon
>> > to review all the recordings, and we plan to publish our results here >
>> and
>> > in QEX on Sunday October 8th.
>> >
>> > Please let us know if you think weâve missed anything in our planning.
>> > Nick and I are both âelderlyâ and we want to get this eclipse right so
>> > we
>> > donât have to wait for the next one.
>> >
>> >
>> > Cheers!
>> >
>> > Mark Durenberger, mobile
>> >
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