[600MRG] How Much Better Today?

[John Langridge]

This will be a nice exercise for someone.  I have a logbook full of CW Q's
over 500 miles with most being in excess of 1300 miles with many of the
usual suspect, XJM leading the pack, if that data would be useful in
someone's analysis.

My first thoughts are the fantastic improvements in RX technology and the
fact that they continue to get better everyday.  I imagine a K3 or Ensemble
II LF adjacent to a Regen would show the modern stuff beats the pants off
the Regen, even with good quality RX antennas.  I think XJM actually tested
this since he built a regen so he may be able to comment with some real
data for someone doing the analysis.

XJM also pointed out at our hamcom discussion forum that rx antennas have
improved greatly and gotten smaller, referencing antennas like the K9AY
loop and other small, close spaced vertical arrays.. Beverages are not
necessary and perhaps not even as good in many respects due to the required
lengths at these freqs for a reasonable pattern.  I do think the smaller RX
antenna possibilities compared to the past are significant.  Along similar
lines, the good news is that there seems to be a lot of interest in the
topband community where good weak signals stations are already in existence
and only need to be outfitted to transmit.


SO I look forward to seeing this develop.

73!

John KB5NJD / WG2XIQ..


On Fri, Jul 3, 2015 at 8:06 AM, Frank Lotito <k3dz at live.com> wrote:

>
> I would like to propose an academic exercise that is beyond my present
> capabilities, unless I want to risk a cerebral incident.  Maybe one or more
> of the readers can "quantitatively" demonstrate that indeed in the last 90
> to 100 years significant progress has been made in "2-way communication" at
> wavelengths "greater than 600 meters."  The exercise: Can long path
> (greater than 500 miles) communications be reliably accomplished between
> today's "amateurs and Part 5 licensees, with their ERP and typical antenna
> constraints" in comparison to long path communications from 90 to 100 years
> ago as practiced by radio services of that era, be they amateur,
> government, military and commercial radio-telegraph?  This could be done by
> constructing a "model" of all the key factors (blocks) in the transmit /
> receive communications path with each block in the model characterized with
> a quantitatively determined range of of its transfer function, S sub 21.
>
> I would suggest that initially the analysis exclude QRSs, JT-9 and WSPR
> modes. After the "communications path model" is developed, we can then
> insert the more advanced communications modes to demonstrate how a poor to
> marginal current era station might be elevated to an effective (but
> painfully slow w.r.t baud rate) communications station.  The model could be
> used by present and future 600 / 630 and 220 meter participants to
> determine which updates to their present / proposed station  would get them
> the best bang for the buck.
>
> Using a similar approach around some 9 years ago, WB8YYY and WN3F (now
> W2VDX) co-authored a 2-part article that appeared in the Antique Wireless
> Association's "The AWA Journal", January 2006, pages 26-28, and April 2006,
> pages 40-42.  They tried to "quantitatively" demonstrate trans-Atlantic
> communications of the initial Marconi transmissions between the (now)
> Canadian Maritime provinces and Ireland.  The co-authors attempted to put
> performance numbers to items such as antenna efficiency, path loss,
> detector sensitivity, information band-width, transmitter power, etc.
> Using an on-line Excel Spread Sheet, the reader could use the authors'
> performance numbers, or change one or more performance numbers to see what
> would happen.  I would assume that the EME amateurs have done similar
> analysis (plural) over the years.
>
> For this particular exercise, I would submit we do know with reasonable
> reliability reliably the "black box" S-Factor transfer function S sub 21 of
> each block of each block (stage) of a modern transmit and receiving 2-way
> path.  For 90-100 year old equipment educated guesses may be the best than
> can be done for the "communications path model."
>
> Last, you may ask why spend the time modeling a 90-100 year old transmit /
> receive station.  The old vs new comparison reaffirming the advantages of
> using technology to overcome obstacles that could only be breached in the
> past with brute force.  The old vs new modeling may also attract to the
> ranks of Lowfers the amateur who's interests lie with the historical
> aspects of communication, including the plethora of rather simple
> "hollow-stage designs," alla pre-WW2 designs.  This past winter we saw an
> example of a historical 630 meter CW transmitter built by NO3M / WG2XJM.
>
> 73 Frank K3DZ / WH2XHA
>
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