On Jul 4, 8:45 pm, wrote:
wrote:
I have installed a FAA approved NDBbeaconhere at our private
airport located in Manchester,TN .
TheBeaconis transmitting on 529 KHZ Carrier power is 50 watts the
facility Id is : LYQ
I have shunt feed a 120 foot high Rhon 25G tower. The tap wire (3/8
dia aluminum 'power line' cable) is at the 90 foot level runs down
the face of the tower with 24 inch spacing to the matching network.
I am using the 'Gamma' match network : the SWR is down to 1.2 or so.
The top of the tower has 4 ten foot radials
The base of the tower has 8 200 foot 3/ 8 inch aluminum cable
radials we plan to add more.
The tower has a 3/8 'power line' type cable from the top to the base
to ensure bonding of each section.
When I fly the Company's Jetstar from 1000 to 41,000 feet, I get
solid points on the RMI indicator:
when I pass right over thebeacontower the RMI needle swings to the
tail indicating positive station passage.
The problem is the range of the LYQ beaconit seems to work 10 miles
or less??? The airplane has dual ADF systems that work perfect.
As an aside, 10 miles away, is another ADFbeaconon 332 KHZ 25
watts! using the traditional three strand 'flat top' suspended
between two telephone poles. The vertical radiator for thisbeaconis
less than 60 feet high : I can track thebeaconout to 70 miles or so!
Is a shunt feed tower lossy??? poor radiator??? comments???
I am a Ham op WA4SZE : by the way, we will QSL thebeaconwhen we
get it commissioned.
Thanks!!

More radials certainly won't hurt, especially since at this freq 200
feet is short.

What's the ground around it like?

--
Jim Pennino

Remove .spam.sux to reply.

open land flat, somewhat damp covered with grass the radials lay on
top of the ground The beacon is on air right now going to leave it
on tonight for reception reports do you think a shunt feed tower is
not good?? I could jack up the tower and insulate from ground it
then series feed do you think that would be better??? lots of work
but might be worth the effort!

On Jul 4, 8:59 pm, wrote:
On Jul 4, 8:45 pm, wrote:



wrote:
I have installed a FAA approved NDBbeaconhere at our private
airport located in Manchester,TN .
TheBeaconis transmitting on 529 KHZ Carrier power is 50 watts the
facility Id is : LYQ
I have shunt feed a 120 foot high Rhon 25G tower. The tap wire (3/8
dia aluminum 'power line' cable) is at the 90 foot level runs down
the face of the tower with 24 inch spacing to the matching network.
I am using the 'Gamma' match network : the SWR is down to 1.2 or so.
The top of the tower has 4 ten foot radials
The base of the tower has 8 200 foot 3/ 8 inch aluminum cable
radials we plan to add more.
The tower has a 3/8 'power line' type cable from the top to the base
to ensure bonding of each section.
When I fly the Company's Jetstar from 1000 to 41,000 feet, I get
solid points on the RMI indicator:
when I pass right over thebeacontower the RMI needle swings to the
tail indicating positive station passage.
The problem is the range of the LYQ beaconit seems to work 10 miles
or less??? The airplane has dual ADF systems that work perfect.
As an aside, 10 miles away, is another ADFbeaconon 332 KHZ 25
watts! using the traditional three strand 'flat top' suspended
between two telephone poles. The vertical radiator for thisbeaconis
less than 60 feet high : I can track thebeaconout to 70 miles or so!
Is a shunt feed tower lossy??? poor radiator??? comments???
I am a Ham op WA4SZE : by the way, we will QSL thebeaconwhen we
get it commissioned.
Thanks!!

More radials certainly won't hurt, especially since at this freq 200
feet is short.

What's the ground around it like?

--
Jim Pennino

Remove .spam.sux to reply.

open land flat, somewhat damp covered with grass the radials lay on
top of the ground Thebeaconis on air right now going to leave it
on tonight for reception reports do you think a shunt feed tower is
not good?? I could jack up the tower and insulate from ground it
then series feed do you think that would be better??? lots of work
but might be worth the effort!

As an aside, I wonder if this is proof that a shunt feed tower is no
good??? I can SEE the tower (runway) over the nose of the airplane
at 15 miles out! yet the RMI indicator is wandering! The beacon
ID is in the noise!

I get a good match but the band width is NARROW! this indicates to
me that the Q is high just as it should be? the RF amp meter is
showing current thru the vertical run up the tower face if your
careless around the 2300 pf vac cap you get a nice RF burn.

By the way, I made a mistake, I am using an omega match the values of
the caps:

C-1 500 pf ( from 50 ohm coax center conductor to 2300 PF Vac Var
cap )

C-2 2300 pf vertical wire run thru C-2 2300 pf cap then ground


thanks!!!!

As an aside, I wonder if this is proof that a shunt feed tower is no
good??? I can SEE the tower (runway) over the nose of the airplane
at 15 miles out! yet the RMI indicator is wandering! The beacon
ID is in the noise!

I get a good match but the band width is NARROW! this indicates to
me that the Q is high just as it should be? the RF amp meter is
showing current thru the vertical run up the tower face if your
careless around the 2300 pf vac cap you get a nice RF burn.

By the way, I made a mistake, I am using an omega match the values of
the caps:

C-1 500 pf ( from 50 ohm coax center conductor to 2300 PF Vac Var
cap )

C-2 2300 pf vertical wire run thru C-2 2300 pf cap then ground


thanks!!!!

I have just run a preliminary NEC model. I am showing a gain of
-9 dBi at an elevation angle of 10 deg. at 530 kHz. Directly overhead the
gain is about -26 dBi. A typical matching network should
have a loss of about 4 dB, for a TRP of around 1 W or so.
The input impedance will be about 0.2+j176. You should have about
10 A RMS in the base of the gamma match vertical wire and, 1.7 kV RMS ,
assuming a 4 dB loss in the matching network.

My model needs some refinement, but should give a ball
park idea of what to expect. I did not understand exactly how you
are using two capacitors to match the antenna.

Regards,

Frank (VE6CB)