I have come by a Tonna 9 element yagi for 430MHz to 440MHz. The driven
element is a folded dipole and has an n-type connector attached. SWR looks
correct and it works but there is a slight skew to the radiation pattern.
The n-type connector is potted in a plastic or epoxy and looks too small to
have any sort of balanced to unbalanced device in it. I intend putting a
ferrite choke on the feed cable to help. Tonna antennas have a good
reputation and I am surprised at the apparent feed method. Does anyone know
if I have missed something?
Dick G4BBH

"Richard Ferryman" wrote in message
...
I have come by a Tonna 9 element yagi for 430MHz to 440MHz. The driven
element is a folded dipole and has an n-type connector attached. SWR looks
correct and it works but there is a slight skew to the radiation pattern.
The n-type connector is potted in a plastic or epoxy and looks too small to
have any sort of balanced to unbalanced device in it. I intend putting a
ferrite choke on the feed cable to help. Tonna antennas have a good
reputation and I am surprised at the apparent feed method. Does anyone
know if I have missed something?
Dick G4BBH
Hi
As far as I remember F9FT ,designer of those antennas, was not
convinced of the usefullness of balancing devices for long yagis .
He said that the slight skew was the only real drawback of not using
any .
I believe you are on your own to prove he was wrong :-)



--- news://freenews.netfront.net/ - complaints: ---

First you cannot check antenna resonance with a SWR meter, that only tells the story of the feed line.
You need a dip meter or a antenna analyzer.

Second - you can use a loop, or a 1:1 Balun inline or beads..

My question is - what frequency do you want it for and what do you want to do with it =- transmit or receive?

430 - 440 is not within the parameters of amateur radio for repeaters....
You could talk simplex or work slow scan television and CW / Digital modes and that is about it.

Channel Jumper wrote:
430 - 440 is not within the parameters of amateur radio for
repeaters....
You could talk simplex or work slow scan television and CW / Digital
modes and that is about it.

Only in your limited mind.

In UK we have 430MHz to 440MHz. I checked the 'SWR' by measuring return
loss at 1MHz steps from 420MHz to 450MHz.. The radiation pattern was
measured outdoors above a snow covered field (the nearest thing I have to
laboratory conditions!) at 435MHz and polar plot made automatically. I
also ran the test with two ferrite blocks on the cable next to the antenna
connector. These were of unknown type but supposed to be similar to type
67. The blocks eliminated the skew with no measurable change in return
loss. The initial skew was really quite small compared with the 3dB
beamwidth but was recognisable on the plot, particularly on the sharper rear
lobes. Curiously there is no skew shown on the plot in the manufacturers
datasheet 220909e.pdf but their photo does show a black 'lump' just to the
rear of the connector. Perhaps they did have a ferrite on there after all!
Dick G4BBH


"Channel Jumper" wrote in message
...

Richard Ferryman;800950 Wrote:
I have come by a Tonna 9 element yagi for 430MHz to 440MHz. The driven

element is a folded dipole and has an n-type connector attached. SWR
looks
correct and it works but there is a slight skew to the radiation
pattern.
The n-type connector is potted in a plastic or epoxy and looks too small
to
have any sort of balanced to unbalanced device in it. I intend putting
a
ferrite choke on the feed cable to help. Tonna antennas have a good
reputation and I am surprised at the apparent feed method. Does anyone
know
if I have missed something?
Dick G4BBH

First you cannot check antenna resonance with a SWR meter, that only
tells the story of the feed line.
You need a dip meter or a antenna analyzer.

Second - you can use a loop, or a 1:1 Balun inline or beads..

My question is - what frequency do you want it for and what do you want
to do with it =- transmit or receive?

430 - 440 is not within the parameters of amateur radio for
repeaters....
You could talk simplex or work slow scan television and CW / Digital
modes and that is about it.




--
Channel Jumper

Yep - many modes, simplex or duplex. SSB, CW, AM, FM, all the digital
modes, DATV which is becoming popular on the band in Europe. Almost any
mode that exists on the other HF or VHF bands. Unfortunately 13.1 dBi is
not quite up to EME standards :-)
I use a pair of home made yagis fed as circular polarisation on this band
for satellite operation with great success.
The Tonna will be used for monitoring beacons and also for monitoring
meteor pings. The beamwidth is ideal for this.
It's all there - if you try!
Dick G4BBH


"Rob" wrote in message
...
Channel Jumper wrote:
430 - 440 is not within the parameters of amateur radio for
repeaters....
You could talk simplex or work slow scan television and CW / Digital
modes and that is about it.

Only in your limited mind.

On 1/21/2013 4:32 PM, Richard Ferryman wrote:
In UK we have 430MHz to 440MHz. I checked the 'SWR' by measuring return
loss at 1MHz steps from 420MHz to 450MHz.. The radiation pattern was
measured outdoors above a snow covered field (the nearest thing I have to
laboratory conditions!) at 435MHz and polar plot made automatically. I
also ran the test with two ferrite blocks on the cable next to the antenna
connector. These were of unknown type but supposed to be similar to type
67. The blocks eliminated the skew with no measurable change in return
loss. The initial skew was really quite small compared with the 3dB
beamwidth but was recognisable on the plot, particularly on the sharper rear
lobes. Curiously there is no skew shown on the plot in the manufacturers
datasheet 220909e.pdf but their photo does show a black 'lump' just to the
rear of the connector. Perhaps they did have a ferrite on there after all!
Dick G4BBH

What did you use to do the plot? I notice you said "automatically". I
saw some software around a few years ago but haven't looked lately. We
do fairly decent gain measurements at NLRS Aurora (nlrs.org) and Central
States, but it's far far from automatic and not also the pattern.

tom
K0TAR

I use PolarPlot version 3.2.7 which can use the PC soundcard to make
received signal measurements or a wattmeter available in kit form from Fox
Delta. The software is freeware and runs under most Windows versions Win
2000, XP, Vista and Win 7. I don't know about Win 8. www.g4hfq.co.uk I
think the PM3A-USB kit is currently about $68. The help file 'Getting
Started' page is very helpful. Rotation of the antenna can use any rotator
once you calibrate the time of rotation. A single pulse starts the process.
I use a stepper motor drive which steps in 0.1 degree steps and is
switchable for 60, 180, 360 or 720 seconds for 360 degrees rotation.
Dick G4BBH

"tom" wrote in message
. ..
On 1/21/2013 4:32 PM, Richard Ferryman wrote:
In UK we have 430MHz to 440MHz. I checked the 'SWR' by measuring return
loss at 1MHz steps from 420MHz to 450MHz.. The radiation pattern was
measured outdoors above a snow covered field (the nearest thing I have to
laboratory conditions!) at 435MHz and polar plot made automatically. I
also ran the test with two ferrite blocks on the cable next to the
antenna
connector. These were of unknown type but supposed to be similar to type
67. The blocks eliminated the skew with no measurable change in return
loss. The initial skew was really quite small compared with the 3dB
beamwidth but was recognisable on the plot, particularly on the sharper
rear
lobes. Curiously there is no skew shown on the plot in the
manufacturers
datasheet 220909e.pdf but their photo does show a black 'lump' just to
the
rear of the connector. Perhaps they did have a ferrite on there after
all!
Dick G4BBH

What did you use to do the plot? I notice you said "automatically". I
saw some software around a few years ago but haven't looked lately. We do
fairly decent gain measurements at NLRS Aurora (nlrs.org) and Central
States, but it's far far from automatic and not also the pattern.

tom
K0TAR

On 1/21/2013 7:00 PM, Richard Ferryman wrote:
I use PolarPlot version 3.2.7 which can use the PC soundcard to make
received signal measurements or a wattmeter available in kit form from Fox
Delta. The software is freeware and runs under most Windows versions Win
2000, XP, Vista and Win 7. I don't know about Win 8. www.g4hfq.co.uk I
think the PM3A-USB kit is currently about $68. The help file 'Getting
Started' page is very helpful. Rotation of the antenna can use any rotator
once you calibrate the time of rotation. A single pulse starts the process.
I use a stepper motor drive which steps in 0.1 degree steps and is
switchable for 60, 180, 360 or 720 seconds for 360 degrees rotation.
Dick G4BBH


Thanks. I am pretty sure that was the one I saw a few years ago. And I
have some of G4HFQ's other software. Good stuff.

tom
K0TAR

I am looking to cut an antenna for 70cm. I have seen lot of designs for the
dual band like Slim Jim or J Pole or Ladder Line. Lots online but they are
dual banders.

Anyone have a good recommendation for a single band 70cm antenna? I have
ladder line (450ohm) and I have RG8u coax with bnc connector on one end
(about 25ft.)

Any ideas for a single band 70cm? Can someone post a good link or good
dimension? I don't have a "Dip meter or antenna analyser".

Thanks

73s





"Channel Jumper" wrote in message
...

Richard Ferryman;800950 Wrote:
I have come by a Tonna 9 element yagi for 430MHz to 440MHz. The driven

element is a folded dipole and has an n-type connector attached. SWR
looks
correct and it works but there is a slight skew to the radiation
pattern.
The n-type connector is potted in a plastic or epoxy and looks too small
to
have any sort of balanced to unbalanced device in it. I intend putting
a
ferrite choke on the feed cable to help. Tonna antennas have a good
reputation and I am surprised at the apparent feed method. Does anyone
know
if I have missed something?
Dick G4BBH

First you cannot check antenna resonance with a SWR meter, that only
tells the story of the feed line.
You need a dip meter or a antenna analyzer.

Second - you can use a loop, or a 1:1 Balun inline or beads..

My question is - what frequency do you want it for and what do you want
to do with it =- transmit or receive?

430 - 440 is not within the parameters of amateur radio for
repeaters....
You could talk simplex or work slow scan television and CW / Digital
modes and that is about it.




--
Channel Jumper