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RE: A couple more Tonna Questions



Hi Joe

> 1. How is the antenna connected to a crossboom or mast?  (Would it be
> easy to attach it in an X pattern or only in a + pattern?)

I have only ever attached them in a + pattern. I will have to double check
to see if the clamps allow X as well - it's been a few years since I last
looked. I have a vague recollection that the mast clamp did have a groove
for this.

> 2. The elements appear to be insulated from the boom.  Is this correct?

Good question. They use plastic clips screwed to the boom that hold the
elements to the boom, metal on metal, but whether physical connection occurs
is moot due to the oxidation of the alumin(i)um.

> 3. Has anyone tried phasing 2 of the "satellite special" antennas 20899
> (19el on 435 MHz + 9 el on 145 MHz) for circular polarization?

Yes: I never got this working too well. Primarily this was because I never
managed to get great even moderately good 50 ohm matching.

> 4. The web site says the 2 x 19 element 435 MHz antenna 20938 has 'N'
> connectors, is this a recent change as some users reported it had lugs?

The 2m crossed has bazooka/sleeve baluns on each plane and N type sockets.
The 70 cm version has only lugs and no balun, unless something has changed
recently. The non crossed 70 cm versions have a balun.

> 5. Does Tonna provide a phasing harness for the 70cm 2 x 19 (20938) and
> 2 meter 2 x 9 (20818) satellite antennas?

They do (or at least did), but there's nothing special to them. Building
your own is certainly an option. The elements are not offset by 1/4 lambda,
so you need odd feed lengths after the power splitter. Again, watch for the
matching: it's questionable about the benefits of any attempt at CP phasing
if the matching's up the swanny (Suwanee??).

I have had two pairs of these antennas over the past six years or so, and
personally I never got on with them. Others may have different stories. I
would be interested to know if the crossed polarised version of the 70cm
antenna now has baluns and 'proper' feeds or not. These days I have the
right test equipment (an Anritsu Sitemaster handheld VNA is a wonderful
device!), but time is not on my side. I would love to give them another
shot.

73, Howard G6LVB
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