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   Home   Help Search  
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Author Topic: VHF TEST: Post Your Tips and Lessons Learned here.  (Read 4483 times)

Posts: 5

« on: June 18, 2011, 05:06:14 AM »

1. A 4:1 or better pully system easily  raises a 35 ft Rohn tower/antennas, with two side guy ropes for stability, and four old guys doing the work.
2. Run pully ropes over a rooftop or through a 2nd floor window tied off to a 2x4x8' board with 3 ft span between  window frames for "leverage".
3. Hoisting light weight masts over about 20 ft long  is a lesson in futility, even with just a 4 el 6m yagi and light wt rotator on top. We   turned two of them into inverted L's!
4.  Preplanning, leadership and experience matter.
5. You never have enough tools:  socket wrenches, sledge hammers, rebars for anchors, the new fangled  portable drills/screwdrivers.
6.  Even rural sites have powerline noise QRM.  Contacting the local utility can get it corrected fairly quickly in some cases.
Listen on the operating frequencies and not just on a car's AM radio.
7. In any organization, the 90-10 rule applies.

Posts: 56

« Reply #1 on: June 18, 2011, 11:47:23 AM »

do not get involved in tower raising / aligning dish antennas / any multiworker task if everyone prent is not in agreement with:

One ship, One Captain
XXX is that Captain.

Posts: 5688

« Reply #2 on: June 26, 2011, 08:18:23 AM »

Tower first, beer afterwards...


Posts: 111

« Reply #3 on: July 05, 2011, 02:03:26 PM »

1- Headset is better than a boom mic
2- Boom mic is better than a desk mic
3- any thing is better than a hand mic.
4- when the band drops out, hunt for a beacon.  then keep your antenna pointed at the beacon and find a calling frequency.
5- have patience with weak signals, and control the pileups.  When pileups get out of hand (they can quickly), try running grid prefixes instead of call prefixes.  There may be twenty W6 stations calling, but maybe only one in CN, etc..
« Last Edit: July 12, 2011, 02:43:42 PM by N5XTR » Logged

Joel ~ N5XTR

Posts: 5

« Reply #4 on: July 06, 2011, 09:51:57 AM »

Good tips, XTR!  I found the grid square approach very wise, IF I can ever generate a pile up!

Posts: 2415

« Reply #5 on: July 06, 2011, 09:23:23 PM »

VHF/UHF tips:

HIGHER is better.  When house shopping, Buy or rent the place on TOP of the hill.  Install the antenna as HIGH as you can get it up.  Use only the very LOWEST loss coax feedline you can get. (On a real limited budget, Use some surplus cable TV trunkline "hardline" Usually available close to free)  Keep whatever feedline you use as SHORT as possible to keep loss to a minimum.

Use the highest GAIN antenna you can build or buy.

Only after the above has been done as best as you can, Should a higher power transmitter be considered.


Posts: 5

« Reply #6 on: July 14, 2011, 07:05:25 PM »

AND...Have a back up rig.  My  14 mo old IC7600 quietly stopped transmitting at around 3 pm Sunday. 

One other thing:  Have a  dual needle wattmeter on the output of your rig so you can spot   issues like loss of output,  changing swr, etc.  I usually set it on top of the rig right in front of me.  When the needles stop dancing, even I know Im in trouble.

Posts: 2218


« Reply #7 on: July 22, 2011, 09:25:49 PM »

Stacking two VHF beam antennas vertically is WAY better than a single beam.


Posts: 5

« Reply #8 on: July 23, 2011, 06:30:19 AM »

Thanks, Mike. 

One further Q......Ive heard so much how height is the single most important factor  for successul vhf antennas.  My 5 el yagi has been at 5 ft, then 10 ft and now 15 ft. 

Taking your vertically stacking  recommendation, would there be   similar differences between vertically stacked  yagis at a relatively low ht....say 15 and 23 ft, and  with vertically stacked yagis at much higher hts say perhaps 50-58 or 60-68 ft?
 I understand the higher ants will intercept  stronger sigs  at the resultant lower angles.  So I woner if its worth it to vertically stack yagis at  lower hts as well as higher hts?

Posts: 2218


« Reply #9 on: July 23, 2011, 07:08:48 AM »

Exactly how the ground (and objects on and near the ground) would affect things at low heights would have to be determined by modeling or tests.

For successful VHF / UHF tropo work, it cannot be overemphasized that height is everything.

My vertically stacked Quagis on 2M were at 70' and 78' (not that high, really). What I could work with only 2W on SSB was just amazing.


Posts: 1543

« Reply #10 on: July 23, 2011, 08:34:21 AM »

VHF height..

First if your below the trees, trees absorb VHF and up signals:
      Try to get above them.
      If you cannot, put up as much gain as possible

If you are above the trees:
      You want HAAT that is height above average terrain.
      Antenna gain is always good as that height came with long coax.

Always use the lowest loss coax you can for the situation.  If your
portable that may mean compromise bur for weak signal ops when
your projected coax loss is 2db or greater, make improvements.

Power, always useful but only to the point of enough is when you
can hear them they can hear you.  If you use more than that you
become an alligator (all mouth no ears) as you cannot hear them.
At VHF power is the offset for the other guys weak antenna or
at best a balance against his antenna and power.  You still have
to hear him first.

Other 'test items: 
  Overdriving the radio and amp for an extra few watts makes you
  wider not louder.  Last test, there were a few 20overS9 Es guys that
  were 40-50khz wide with splatter.  Contact power is not 104% of max.
  Thanks for the QRM. 

  There were people in that 40khz chunk that could not work each other
  because of that QRM.  Get a few guys spread out doing that and the band
  is largely unusable in that direction.

  Stations roving or on battery, lower your power as the battery
  goes down.  Most solid state amps(and radios) cannot produce full
  power at 12V, their full power rating is at 13.8V at the radio/amp
  power connector so even losses due to wire counts.  Also if the
  distortion gets high enough, heard but not copyable, happens.
  I had a few like that, they were so overdriven just getting the call
  was a challenge and they were S9, I got one guy (hill topper) to
  turn it down and was then able to copy him very well.   Also
  most radios when you get under 11V start to get unstable with
  FMing on voice peaks or wooping on keying.  Test for that beforehand
  into a dummy load.  Failure to do this puts you in the same group
  as the overdrive QRMers.  I run battery solar from the QTH (power
  supply for the bigger amp) and nominal power is usually 40-80% of
  the amps capability.  If I push for full power I find I have to watch the
  battery voltage or argument it with a power supply or I start getting
  early signs of FM, clipping, and splatter.  FYI: the batteries here are
  150AH wet NiCds and those are both big and flat discharge compared
  to Lead acid/SLA with a float voltage of 13.9V and near dead of 11.4V.
  Suggested Item for battery users (rovers, Portables, Solar/wind/battery)
  is an expanded scale voltmeter (analog) so you can see small changes
  and when your nearing the cutoff voltage for your battery or radio.
  You may be able to use a LCD dpigital panel meter but most sample
  2 to 5 times a second so they will not see battery droop on modulation.
  I'd still use that if you have nothing else.

  Headset boom mic combos are great, turn down the mic gain so
  that the guy next to you, amp fan, and/or the room echo are not
  part of your muddied signal.  Excessive base boost or narrow tinny
  audio buys nothing.  Not loud enough with the gain down try getting
  the mic near your mouth.

  If you have QRM from line noise fix it.  There were a few I worked
  on short line of sight paths that were loud but when I finally worked
  them they admitted they could barely hear.  I cranked the power to
  make i happen but it would have been far easier if they didn't complain
  of S9 local noise.  I gave up on one that was lout to me but never
  heard callers.    Fix the noise.

  Calling frequencies.  Call and move please.


Posts: 5

« Reply #11 on: August 08, 2011, 10:43:04 AM »

Share your successful ways to  increase participation at  finding more ops and loggers

Posts: 810

« Reply #12 on: August 10, 2011, 02:03:45 PM »

If you need wide area coverage for nets etc. consider stacking 2    4 to 6 elements beams to get gain with wider pattern response especially in contesting.
Saves a lot of rotor wear and missed calls.
On 2M my 12E is too sharp for net use and even longer coverage during high traffic times when you need to hear the NC station.
Unless you have the rotor direction zeroed in to use grid squares off QRZ accurately, the rotor takes a beating.
« Last Edit: August 10, 2011, 02:10:56 PM by KM3F » Logged
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