[amsat-bb] Re: Cushcraft A432-20T
domenico.i8cvs at tin.it
Fri Sep 18 13:09:58 PDT 2009
Hi Luc, VE2DWE
Standing behind the reflector connect first one reflector element Vertical
with the U bolt attachement to your left side Then mount a drive element
Vertical with the U bolt attachement to your left side.The driving element
must be mounted with the gamma match arm looking upword and the N
connector looking in your direction i.e. the back of the antenna.
The rest is automatic and straigforward because the Horizontal driving
element will be mounted after the Vertical one closer to the satellite with
the gamma match arm appearing on your right side with the N connector
looking on the back and the U bolt mounted in the lower part of the boom .
Since the driven element is 50 ohm as adjusted in the factory connect a 1/4
electrical wavelength of 75 ohm coax cable to each driven element and
connect it in parallel to a T connector to get an impedance transformation
of about 50 ohm
For RHCP connect to the Horizontal driven element a 1/4 electrical
wavelenght of 50 ohm coax delay line using a double female barrel.
If you add the delay line to the vertical harm then you get LHCP
The A432-20T is a very BAD antenna and because of too many connectors
(one T and one double female ) you will experience very high losses in 70 cm
In a separate email I have sent to you the schematic diagram for the phasing
harness and while it is for the A144-20T the concept is the same
----- Original Message -----
From: "Luc Leblanc" <lucleblanc6 at videotron.ca>
To: <amsat-bb at amsat.org>
Cc: <eu-amsat at yahoogroups.com>
Sent: Friday, September 18, 2009 6:21 PM
Subject: [amsat-bb] Cushcraft A432-20T
> I just get a Cushcraft A432-20T at a recent Hamfest. As per the theory if
the longest matching line is connected to the horizontal element
> and the shortest to the vertical one i should have a RHCP but if i reverse
the connections should i have LHCP? If i rotate the antenna by
> 90 degress how i can determine the horizontal versus the vertical
elements? The only one reference i have is the U bolt attachment to
> determine the horizontal elements or one driven elements is the closest to
the reflector (further away behind the other driven element).
> There is no marking on the beam only the driven elements caps are both
marked with 1/2 SC? This model was not made with a switching device
> and as i don'r have the specs sheet i'm in the blind to configure it to
RHCP as it seems it is the actual UHF standard on the circular
> LEO's fleet?
> Thank's for your help
> Luc Leblanc VE2DWE
> Skype VE2DWE
> DSTAR urcall VE2DWE
> WAC BASIC CW PHONE SATELLITE
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