[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Cushcraft 738XB



Desiccant is designed to absorb moisture, not keep it
out. Once it is saturated it no longer works but does
hold the moisture and if there is no for the moisture
to go is stays put. I would suggest you not try to
seal the box, provide a place where mositure can get
out and the box can breathe.(weather resistant vs
weather proof) Also, be carfull in your choice of
silicon. Most silicon caulks contain acetic acid which
will corrode your circuit board and/or connections in
a short time.

73

Denny  WB8K

--- "Malcolm M. Preston" <np2l@worldnet.att.net>
wrote:
> My KLM 2 m antenna has a circuit board relay switch
> - basically unprotected.
> The foil connection totally coroded itself out.  I
> solved it by hard wiring
> the connections on the board - it' a very simple
> circuit.  Then I slopped
> silicone over the whole thing.  The 440 switch is in
> a box and has given me
> no trouble.
> 
> Mal, NP2L
> St. John, USVI
> ----- Original Message -----
> From: <jbblack@mindspring.com>
> To: AMSAT-BB <amsat-bb@AMSAT.Org>
> Sent: Sunday, January 16, 2000 9:50 AM
> Subject: [amsat-bb] Cushcraft 738XB
> 
> 
> > Am wondering if anyone else on the reflector has
> this particular 70cm
> > antenna.  I hadn't been on the satellites in a
> while when, on Christmas, I
> > noticed that the FO birds and AO-27 were hard to
> receive.  I kept noticing
> > this phenomenon hoping it would get better. 
> Granted, I've got lots of
> > trees, but even in the summer, I could hear well. 
> Now, all of a sudden,
> my
> > operation has gone to 0 due to the fact that I
> cannot hear.
> >
> > Yesterday, I climbed my short tower (23') and
> removed the switchbox on the
> > antenna.  I had sealed it with silicon to keep
> water out.  While I was
> > taking the screws out, however, I noticed that
> there was a proliferation
> of
> > rust on the screws themselves.  Once I got the box
> apart, I noticed a
> white
> > powdery substance all over the circuit board.  I
> am wondering if this came
> > from the dessicant packages I placed in there to
> keep moisture out or if
> the
> > dessicant packages failed and water got in there
> and corroded some
> circuits.
> >
> > I haven't fully taken the switchbox apart yet
> waiting for Tuesday when I
> can
> > get it on the bench and de-solder the RF and DC
> connections on the board
> and
> > spray all of it with contact cleaner.
> >
> > I wonder if it just wouldn't be better to
> circumvent the box and feed RF
> > directly to the driven elements.  Any suggestions?
> >
> > Thanks es 73,
> > Joel
> >
>
-----------------------------------------------------------------------
> > OM:  Joel B. Black, K2SAT     XYL:  Kristie H.
> Black, KF4CHN
> > Eutaw, AL...............EM62      
> kahblack@mindspring.com
> > AMSAT member #32589
> > AMSAT Local Area Coordinator
> > www.mindspring.com/~jbblack
> > jbblack@mindspring.com
> > k2sat@amsat.org
> > AO-10, AO-27, FO-20, FO-29
> > UO-22, KO-25
> >
> >
> >
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG
> courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to
> Majordomo@amsat.org
> >
> 
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy
> of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to
> Majordomo@amsat.org
> 
__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com
----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home