ARLA/CLUSTER: Antena vertical Cushcraft MA6VA

[Carlos Pinheiro]

Caros colegas,

Comprei uma destas antenas já há algum tempo, por ser bastante
discreta(condemónios...), leve, cobrir 6 bandas(6m/10/12/15/17 e 20m) e não
necessitar de radias. Nunca a "afinei". Limitei-me a ajustá-la para as
medidas indicadas pelo fabricante para as diversas bandas e nos 6, 10 e 20m
até ficou razoável, de modo que só há poucos dias resolvi "descê-la" do
telhado e afiná-la e aí constatei que em duas bandas, 17 e 24 Mhz, o "deep"
está fora da banda! mesmo puxando o tubo de afinação todo para fora,
continua "curta", ou seja, ressonante lá para os 19/20 Mhz na banda dos
17m...
Entretanto vi no "eham/review" algo de mt semelhante q aconteceu a um
colega americano:

I bought the MA5V antenna because I needed a stealth like antenna in my
restricted Florida neighborhood and because Cushcraft has (or had) a good
name... until it was bought by MFJ. Antenna arrived and would only tune to
20 meters, all of the four other bands, 10, 15, 12 and 17 had no SWR dip.
Called MFJ and they sent new elements for these bands. Same result... no
dips. Packaged it up ready to send back and have them return my money when
I decided to take off the liquid tape where the coils connected to the
elements to see if the connections were good. It took a lot of scraping and
fussing with an exacto knife to do this. I was surprised to find that they
used enameled wire in the coils and did not scrape the ends of the wires!
What's more the wires were inserted into wire clips on the elements, but
none of them were soldered! I had to scrape off the liquid tape from 20
connections (did the 20 meter coils too), clean off the enamel and solder
all of them. Then, I got the dips and could tune the antenna. Called MFJ
again to tell them how I fixed their antenna... their response, was...
"I'll walk back there and talk to them." Once the connections were fixed,
the antenna worked nicely although its bandwidth is quite narrow on most
bands. The antenna fit the bill as a very small profile stealth antenna
that works, but the experience of getting it working was frustrating, to
say the least. Beware of quality control.

Infelizmente este OM não tem o email no QRZ.com, senão ter-me-ia dirigido
ao mesmo. No entanto acho estranho a falta de contacto referida pois tenho
continuidade(0.1 ou 0.2 Ohm) nas extremidades dos traps(bobinas) Nos tubos
imediatamente antes e depois das bobinas(ou terá algum condensador lá
metido, em paralelo e é aí o mau contacto?).

Peço desculpa pelo "cambão", mas talvez alguém tenha uma ideia antes de
começar a "rebentar" com o lindo isolante esmaltado dos "traps"...

73 de CT1PT

-- 
Carlos Pinheiro
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