Refurbishing my Cushcraft A3S

(1/5) > >>

:
Hi all,

My A3S is 10 years old and it has exceeded my expectations. I can't compare it to antennas I haven't used but it helped me work 300 countries in about 5 years of "air time". However, time and the elements have taken their toll. The various element spacings are out of alignment due to a decade of New England wind and ice storms. This has caused the SWR to climb to unacceptable levels on 10 and 15 meters. Also, I recently added an Alpha 8410 to my station ( I had a Heathkit SB-1000 for all the other prior years I owned the A3S so it's not like the traps have never seen high power) and I believe the extra output power has damaged one of the "TC" traps despite them being rated at 1.5 Kw. I can see changes to my SWR readings on 20 meters once the power is raised above 100 watts. At about 500 watts the SWR jumps to a very high level where I can't get a reading and my Alpha proceeds to have a "SWR Fault".  Also, I can physically see that the "TC" trap is damaged severely as the black internal coil sealant has oozed out and molded with the trap cap.  I ordered 22 end cap replacements for all 11 traps I'll be reusing ( 2 for each trap) as they are all worn out due to weatherization and I ordered a new "TC" trap to replace the damaged one. While I'm waiting for the parts to come in I planned on disassembling the beam and putting it back together so all the various spacings are per specification for the center of the bands.. A Ham in the Phillipines has a detailed website showing how he dismantled the traps and cleaned all the aluminum so it looks like new. Do any of you really think cleaning ALL the aluminum is necessary?  I am going to clean the areas where the elements meet and apply some Penetrox.  Can anybody think of anything I should be doing but which I'm not planning to do?  I live about 100 miles from the ocean so salt water is not a problem here in Western Mass.

As an afterthought what is best solution to use to clean aluminum? I take it the Penetrox is used to make a better electrical connection but does not clean aluminum.

73,

Chris/NU1O

Steve Katz:
I just use 3M "Scotchbrite" cleaning pads to clean the aluminum where the tubing sections overlap and then add "NoAlOx" compound to them (thin film) before putting them back together.

Sounds like a good "rebuild" job.

I had an A4S (very similar, slightly longer, one more 10m single band reflector element, but I believe the traps are identical) for 20 years and never had any problems with it at all, even at 1500W.  I suspect the trap that failed in your case may have taken in some water over time, leading to the failure.

:
Quote from: WB2WIK on September 09, 2011, 10:27:00 AM

I just use 3M "Scotchbrite" cleaning pads to clean the aluminum where the tubing sections overlap and then add "NoAlOx" compound to them (thin film) before putting them back together.

Sounds like a good "rebuild" job.

I had an A4S (very similar, slightly longer, one more 10m single band reflector element, but I believe the traps are identical) for 20 years and never had any problems with it at all, even at 1500W.  I suspect the trap that failed in your case may have taken in some water over time, leading to the failure.




Steve,

I am not familiar with "Scotchbrite" and my Goggle search turned up many types.  Do they make one for aluminum?  Since you only clean the connection joints I am going to assume you think the guy in the Philippines who cleaned every bit of aluminum did some unnecessary work. All hams think their antennas are beautiful but I'm not into cleaning for cleaning's sake.

WOW. My antenna's are all down but I saw saw the K Index at DXSummit and it is at 6! For sure there will be stories all over the NET that the world is about to end.

73,

Chris/NU1O

Lon Kinley:
ScotchBright is a very mildly abrasive fiber pad and you can find them at just about any hardware, grocery, big box or similar store. They are not made specifically for any metal, but are actually made for scouring the inside of cooking pots and pans.

:
Quote from: W3LK on September 09, 2011, 12:54:05 PM

ScotchBright is a very mildly abrasive fiber pad and you can find them at just about any hardware, grocery, big box or similar store. They are not made specifically for any metal, but are actually made for scouring the inside of cooking pots and pans.




Thanks, I found it at the local grocery store.

Navigation

[0] Message Index

[#] Next page