[amsat-bb] Moxon on top a Baofeng UV-5R for 70cm experiment
Saguaroastro at cox.net
Tue Mar 17 00:37:21 UTC 2015
Here is a link to a program as m called MOXGEN. It will calculate the dimensions for a moxon given the frequency &wire size. Once done it'll generate an EZ-NEC model for the antenna.
The model should give you a good idea of the gain, beamwidth & front to back
I'd be interested I what it tells you.
On March 16, 2015, at 17:05, Pavel Milanes Costa <co7wt at frcuba.co.cu> wrote:
Hi to all.
Yesterday I was evaluating the construction of a small antenna for
portable use on top of the Baofeng UV-5R... at the end I finished with
two choices CJU vs moxon for 70cm handheld
After some modeling I choose the moxon over the CJU because:
- Less wire
- Less weight
- Less stress for the connector
- Just ~0.6 dB down vs the CJU
- By far better F/B ratio
After completion of the first "prototype"...
I successfully heard the CW beacon of Jugnu, CO-57, CO-58, PRISM and others.
The fire test will be tonight on SO-50, I know now I will copy ok, but
the challenge is eliminate the desense of having two yaguis on a cross boom.
I will test the moxon handheld on RX (UHF) and a Jpole for the 2m uplink
with 5W of a handheld.
I have not measured the SWR of the moxon, but with the simulation the
measures are not "that critical" for getting a less than 1:2 of SWR over
the entire 70cm band (1:3 bandwidth is about 16 Mhz)
The moxon "experiment" is just ~25 cm width and ~15 cm height (may be
smaller also, the minimal height is ~10cm + connector) over the Baofeng
UV-5R, there is no much stress on the connector.
I used a SMA to BNC adapter (the kind with a rim to fit tight to the
radio body) and then a clamp on BNC (male) with a bronze tube as coaxial
shield/boom of the antenna.
Wish me luck with the desense problem...
M.Sc. Pavel Milanes Costa, CO7WT
SYSOP Nodo Gateway CO9JAZ
Ciudad de Camagüey, Camagüey, Cuba.
Cell: (+53) 53-847819
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