Refurbishing Antennas
 

My old Cushcraft A3 is more than likely due for a take down and
refurbish. Ive not really touched it in a long time and have never
opened the traps. 15m is suffering so I may have a bad trap.

So, I did a net search and not too many have posted how its done.
SOOOO, with that I come hat in hand for hints/tips etc from those that
have went there.


Scotty N7HJ

"Rick Scott" wrote in message
ps.com...
My old Cushcraft A3 is more than likely due for a take down and
refurbish. Ive not really touched it in a long time and have never
opened the traps. 15m is suffering so I may have a bad trap.

So, I did a net search and not too many have posted how its done.
SOOOO, with that I come hat in hand for hints/tips etc from those that
have went there.

Scotty N7HJ


Scotty -

The first step I would take is get replacement stainless steel hardware - IF
this was version before that usage.

These web pages may be helpful
http://www.iol.ie/~bravo/Troubleshooting%20Traps.htm

If you try to disassemble the driven element traps on the Cushcraft A3 - the
proper way to remove the trap covers is to slip the black trap caps off.
If the traps have been up in the weather for a while, it may be difficult to
remove them without breaking them.
You can order replacement caps from Cushcraft. they were around $1.30 apiece
in 2001. There are 24 caps on an A3S.

When your A3 was new, the traps had a paper sticker indicating which was
which. Why the traps weren't engraved or marked with a permanent sticker is
a mystery that only CC can answer. Taking them apart though is not one of
them though! Inside - the traps look the same.

1) Attach them using very short leads to a HP network analyzer and punch up
the Smith chart. Start around 18 Mhz , and crank the frequency up until
the readout on the display switches from inductance to capacitance. Note
that
frequency. You will find 2 whose frequency is about 150Kz higher than the
other 4.

2) Use a grid dip meter placed end to end on a non-conductive table to
determine which 2 resonate higher that the other 4. The network analyzer
is a better approach.

Cushcraft directions (via email on towertalk / contesting.com) for trap
disassembly:

The traps of the A3 and A3S can only be separated one way.
First of all, the 10 meter traps are the same and you can use them in any
position. Be sure the end with the contact screw for the body to element
junction is
nearest the boom.
The 15 meter traps can be identified by the fact that they are "swagged" to
a smaller tubing size on the outboard side. There are 2 different types of
15 meter traps. 4 of the traps are used in the reflector and driver
elements. There are two 15 meter traps that are used in the director and
they have a higher frequency of resonance. That is the only way to tell the
difference. Check the traps with a dip meter and that should tell you which
are which."

Cushcraft used to perform this service often for a nominal fee, but it looks
like that level of support has stopped.

gb wrote:

Outstanding information. Exactly what I needed. Thanks a ton

Scotty N7HJ

I dunno for sure but, this might work ...
has anyone out there tried putting traps into a food dehydrator for a few
days to dry out ?
then of course, you would seal it up with something like scotchkote or
urethane.

"Rick Scott" wrote in message
ps.com...
My old Cushcraft A3 is more than likely due for a take down and
refurbish. Ive not really touched it in a long time and have never
opened the traps. 15m is suffering so I may have a bad trap.

So, I did a net search and not too many have posted how its done.
SOOOO, with that I come hat in hand for hints/tips etc from those that
have went there.


Scotty N7HJ

Hal Rosser wrote:
I dunno for sure but, this might work ...
has anyone out there tried putting traps into a food dehydrator for a few
days to dry out ?

Nitrogen flushing always worked for me, at least for awhile.
--
73, Cecil http://www.qsl.net/w5dxp


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"Cecil Moore" wrote in message
...
Hal Rosser wrote:
I dunno for sure but, this might work ...
has anyone out there tried putting traps into a food dehydrator for a
few
days to dry out ?

Nitrogen flushing always worked for me, at least for awhile.
--
73, Cecil http://www.qsl.net/w5dxp


I guess the word is "Kool!"
our Wal-Mart ran out of nitrogen toilets, so nitrogen flushing may be a
second alternative.

Rick Scott wrote:

My old Cushcraft A3 is more than likely due for a take down and
refurbish. Ive not really touched it in a long time and have never
opened the traps. 15m is suffering so I may have a bad trap.

So, I did a net search and not too many have posted how its done.
SOOOO, with that I come hat in hand for hints/tips etc from those that
have went there.


Scotty N7HJ


And one other easy thing that definately helps on VHF/UHF, is cleaning
the aluminum elements. I use scotchbrite pads with aluminum cleaner.
As I remember Brasso maight be a substitute. Someone correct me if I'm
wrong there. If the cleaners aren't available, just the pads plus light
detergent followed by a good rinse will do a lot to clean up the skin of
the element.

Tom
K0TAR

Tom Ring wrote:
Rick Scott wrote:

My old Cushcraft A3 is more than likely due for a take down and
refurbish. Ive not really touched it in a long time and have never
opened the traps. 15m is suffering so I may have a bad trap.

So, I did a net search and not too many have posted how its done.
SOOOO, with that I come hat in hand for hints/tips etc from those that
have went there.


Scotty N7HJ


And one other easy thing that definately helps on VHF/UHF, is cleaning
the aluminum elements. I use scotchbrite pads with aluminum cleaner. As
I remember Brasso maight be a substitute. Someone correct me if I'm
wrong there. If the cleaners aren't available, just the pads plus light
detergent followed by a good rinse will do a lot to clean up the skin of
the element.

Tom
K0TAR

What do you do to protect them afterwords ?

Scotty N7HJ