[WARC] Wabasha ATV email copy of 10/10/08

[jonmcpete at cpinternet.com]

This is a copy of email sent to Wabasha Hams 10-10-08:


QST from Wabasha County (and other hams who may be
interested in what's happening here):

A quick note about the ATV repeater going into service soon
(months):  

Will send out details at a later date (unless you would
rather not receive them in which case just respond to this
email with a "cease and desist" type message and I won't
bother ya no more.)  This has been sent to hams in Wabasha
County and some hams in neighboring counties who might be
interested in using/ knowing about/ being warned of the
repeater.  

To find out when testing is being done just check on the
Wabasha 2m. repeater 146.745- (136.5) and give a shout.  I
will be testing it off and on over the next few weeks
starting with just sending a video only test pattern/ID for
alignment and range checking purposes.  Will only be running
about 20 W. for now.  Will add the audio after I have the
exciter/amp combo properly adjusted.  For now am using
vertical polarization into part of a diamond 700 antenna at
about 140 feet on the tower above Reads Landing.  "Part"
meaning this is most of what was left after lightning took
of the top a couple years ago and we replaced it with the
new antenna.  Also, the 1/2" heliax is old and will be
upgraded when everything is done being tested.  This was
courtesy of Tony, W0IU, and is about the fourth repeater it
has done duty on.

For those not familiar with ATV, this is "regular TV", not
slow scan.  Real NTSC, 525 line, 30 frame per second, color
TV (sorry not hidef; not even stereo).

This will be an "in-band" repeater with receive and transmit
sites at first just separated by about 90 feet on the tower,
then as we go to higher power they will be on two towers
about two miles apart with the receive site on Roger's,
KI0F, tower.  Will use a link frequency between them on 900
or 1200 MHz as well as probably other in/out frequencies in
those bands as needs arise.

Repeater input frequency will be 420-426 MHz (video carrier
at 421.25) and output at 438-444MHz (video carrier at
439.25)(Yes, I know that sounds backwards from some other
states but it's right).  Again, the polarization will be
vertical unless we end up QRM-ing any 70. cm. FM repeaters
with their outputs in the 442-444 MHz portion of the band. 
The only close ones to here are:  Red Wing 442.25 and Waseca
442.30 which are not close to our color burst frequency of
about 442.83 and pretty far out from the main video carrier
at 439.25 so as to assure that our video signal is not
likely to carry much energy at that frfequency unless
photographing someone in a herring-bone suit.  The sound
subcarrier will be at about 443.740-443.760 (ya, kinda wide)
and this should not bother Austin voice at 443.50; Albert
Lea at 443.525; MAYBE Waseca though at 443.75; not other
Waseca at 443.825; nor Rochester nor Winona at higher yet
output voice frequencies.  Durand, WI is physically the
closest but at 443.40 should not be a problem.

PLEASE REPORT ANY POSSIBLE CONCERNS ABOUT QRM TO ME.  I
THINK I HAVE TAKEN INTO ACCOUNT ALL POSSIBLE FREQUENCY
PROBLEMS INCLUDING THIRD HARMONIC INTERACTIONS FROM TWO
METER MACHINES, SECOND AND HIGHER HARMONICS (KINDA "HIGHER
ORDER SIDEBANDS") OF OUR OWN COLOR BURST AND AUDIO
SUBCARRIERS ETC.  WASECA MIGHT BE THE ONLY PROBLEM AND WE
CAN ALWAYS CHANGE POLARITY OR USE A DIRECTIONAL PATTERN TO
OUR ANTENNA OR, HEAVEN FORBID, LOWER OUR TRANSMIT POWER.  I
SERIOUSLY DOUBT THAT WE WILL GET A SIGNAL THAT FAR ANYWAY
...BUT....IT MIGHT POSE A PROBLEM FOR SOMEONE IN SOMEPLACE
LIKE WANAMINGO WHO WANTS TO USE THAT 70.cm. MACHINE IN
WASECA WHO IS BEING QRMed BY OUR SOUND SUBCARRIER.  Then
again, what are the odds of those needs having to be met at
the same time???

I will keep a log of all test times/power levels and such to
help sort out interference issues.

For those of you (ALL OF YOU?) who do not have ATV receiving
equipment you CAN pick this signal up by using a
"cable-ready" TV tuned to CABLE CHANNEL 60 but hooking an
outside antenna to the TV antenna terminals.  My first few
experiments comparing a typical outdoor tv yagi (horizontal
pol.) with a simple vertical 440 MHz antenna showed the
vertical worked better.  You could always twist your yagi 90
degrees so the elements are vertical of course but I will
pass along some cheap solutions later.  Note that the tuners
for the "cable channels" in most tv's are not very sensitive
as they only need to receive a quite strong signal on the
cable and not a weak signal through the air so you do not
get very good reception this way.  More later on cheap
preamp.s and such.  By the way, you will be able to monitor
your neighbor ham working INTO the repeater on cable channel
57.  Our (ham's) signals could always get into the "CABLE
SYSTEM" and interfere with the programming they have on
"our" frequencies but I'm sure they will just take any of
that interference as a demonstration that they need to
upgrade their coax!

73, Jon
WA0UNB