Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Refurbishing my Cushcraft A3S  (Read 7143 times)
NU1O
Member

Posts: 2704




Ignore
« on: September 09, 2011, 08:16:29 AM »

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

Logged
WB2WIK
Member

Posts: 20613




Ignore
« Reply #1 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.

Logged
NU1O
Member

Posts: 2704




Ignore
« Reply #2 on: September 09, 2011, 12:06:07 PM »

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
Logged
W3LK
Member

Posts: 5639




Ignore
« Reply #3 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.

Logged

A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
NU1O
Member

Posts: 2704




Ignore
« Reply #4 on: September 09, 2011, 01:44:35 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.
Logged
WB2WIK
Member

Posts: 20613




Ignore
« Reply #5 on: September 09, 2011, 01:59:21 PM »

Yep, that's the stuff.  It is meant for scouring about anything that can be scoured. Wink

I note they make it in different colors like green and dark red.  I'm not even sure what the difference is, other than the color.  I've used both, and both work fine on aluminum.

I would not use "steel wool."
Logged
NU1O
Member

Posts: 2704




Ignore
« Reply #6 on: September 09, 2011, 02:27:56 PM »

I suspect the trap that failed in your case may have taken in some water over time, leading to the failure.

I suspect you are correct and no telling what organic creatures are in those traps. Also, the water drainage holes had shifted on some traps and were no longer facing directly downwards on a couple of them.  This antenna should've been maintained yearly but I was off the air for extended periods due to the stuff which always seems to interfere with hamming (work, relationships, etc., etc.)  BTW, the elements did not change length but they had shifted out of the same plane.

The trap which burnt out is on the driven element and I'm assuming (possibly not correctly)  that element sees all the power. I have all sorts of antenna books but I can't recall reading anything about how voltage and current change between a driven element and parasitic element(s).  Possibly because I never had a real reason to know.  At 1500 Watts PEP there should be about 270 Volts and 5.5 Amps. That maybe another explanation as to why a trap on the driven element broke down as opposed to a director or reflector element.

As I was writing this I got a call back from Cushcraft/HyGain and the fellow recommended steel wool to clean the elements. I told him about the ham in The Philippines who cleaned every bit of his elements and he said he may have been combating salt water which is something I did not think of.  I'm 100 miles from Long Island Sound and did not even consider salt water as a potential problem but the guy from Cushcraft (It sounded like Rob from MFJ) said I might want to paint the elements with non-conductive paint.  That sounded like overkill to me but just for the hell of it is there anybody near the ocean who paints their elements to protect from salt water? And how far are you from the sea? Maybe I'll call the local TV station between broadcasts and ask the weatherman just how much salinity is in our rain as compared to the shoreline.

73,

Chris/NU1O


« Last Edit: September 09, 2011, 03:02:22 PM by NU1O » Logged
NU1O
Member

Posts: 2704




Ignore
« Reply #7 on: September 09, 2011, 02:35:27 PM »


I would not use "steel wool."

Steve,

I posted my previous reply before I saw your response.  Steel Wool is exactly what the fellow from Cushcraft recommended and I would think it is too abrasive. He sounded exactly like the guy I spoke to when my linear and current in-rush protector had problems (MFJ & Ameritron Products) about a year ago so they may have the poor guy answering questions for all the subsidiaries now. He maybe overloaded with work and answering questions outside his areas of expertise.

Chris
« Last Edit: September 09, 2011, 02:57:58 PM by NU1O » Logged
WB2WIK
Member

Posts: 20613




Ignore
« Reply #8 on: September 09, 2011, 02:59:57 PM »

It's not the abrasion I'd worry about with steel wool, it's the steel. Wink

Tiny (almost microscopic) steel threads from the steel wool can embed themselves into the aluminum (steel's much harder than aluminum is), even without you seeing that happen.  Once it does happen, it's almost impossible to get it out.  Then, you have a built-in rust mechanism which will begin to rust almost immediately outdoors.

Just not worth it.  I wouldn't use steel wool to polish anything made of aluminum.
Logged
NU1O
Member

Posts: 2704




Ignore
« Reply #9 on: September 09, 2011, 03:33:11 PM »


Just not worth it.  I wouldn't use steel wool to polish anything made of aluminum.

I never gave it much thought but your explanation makes perfect sense.
Logged
K3GM
Member

Posts: 1819




Ignore
« Reply #10 on: September 10, 2011, 03:08:22 AM »

If you haven't disassembled it already, be sure to mark each trap location.  The 10 meter traps are the same and you can use them in any position.  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 as they visually look the same, but were not permanently marked.
« Last Edit: September 10, 2011, 03:10:53 AM by K3GM » Logged
AB4D
Member

Posts: 298


WWW

Ignore
« Reply #11 on: September 10, 2011, 03:42:02 AM »

The different colors of the Scotch-Brite pads designate the abrasiveness. I believe for the consumer line Scotch Brite, Blue is fine, Dark Green is medium, Red/Maroon is Coarse.  I would use the green to clean up aluminum tubing.

They also have industrial Scotch-Brite that you can purchase from most body shop supply house.  They probably will have a better grade of Scotch-Brite for your specific application.

73

Jim

Logged
NU1O
Member

Posts: 2704




Ignore
« Reply #12 on: September 10, 2011, 05:10:35 AM »

K3GM, The traps are still attached and I'm aware of the different 15 meter traps. I also found a site with the resonant frequencies for all three traps and I have the grid dip adapter for my MFJ-259 antenna analyzer. There actually is some faded lettering which says TC on the trap which is damaged, but I will mark the traps clearly when they are taken off the respective elements.  Thanks for the tips.

AB4D, Mine are dark green and say Heavy Duty on the label.  I found some old Comet scouring powder and some aluminum cleaner, also. With some elbow grease these elements are likely to be cleaner than when they were first purchased.

The other day while rummaging through a shed I found all the expensive parts of my very first antenna as a ham: a Butternut HF-6V and I'm going to restore that after I'm finished with the A3S. It's only missing about 12 feet of the top three thin sections which should not be very costly to replace. The 30, 40, and 80 meter coils, along with the high voltage capacitors are all intact. With all the help I'm getting I should get pretty adept at this.

For my winter project I'm going to purchase EZNEC (I've never used modeling software) and see if the A3S can be modified to add 2 elements on 40 meters.  It should be a good learning experience even if my ideas don't pan out.

My sincere thanks to all who responded. These forums on eHam are full of very smart people with a wide breadth of expertise. It's a wonderful site!

73,

Chris/NU1O
« Last Edit: September 10, 2011, 05:16:56 AM by NU1O » Logged
NJ3U
Member

Posts: 125




Ignore
« Reply #13 on: September 11, 2011, 11:19:32 AM »

I'm working on a similar project involving a Mosley TA33jr.  I've been documenting it in the slideshow that lays out the entire antenna proejct.
http://s47.photobucket.com/albums/f190/dad250/Mosley%20Beam%20Antenna%20Project/?albumview=slideshow

I bought it used and the Ham that took it down did an excellent job of marking and bagging all the parts prior to shipping.  So first pointer is mark everything as it is broken down, use a marker to show tuning stops so it can go back together and work.
Scotch Bright and non conductive material brushes work great to get the spiders and bugs out of the traps.  Remember to clean and align the drain holes for proper operation.
I cleaned the slip joints with the ScotchBright pad and applied anti-ox lube to aid in reassembly and future disassembly.  Mosely sent a packet when I ordered replacement parts.
Cushcraft is now owned by MJF, so replacement parts should be available.  Check you end caps, insulators, standoffs for physical damage / cracking.
Remember to use never sieze on the stainless hardware and it's OK for reg steel as well.
Logged
NU1O
Member

Posts: 2704




Ignore
« Reply #14 on: September 11, 2011, 12:47:32 PM »

I'm working on a similar project involving a Mosley TA33jr.  I've been documenting it in the slideshow that lays out the entire antenna proejct.
http://s47.photobucket.com/albums/f190/dad250/Mosley%20Beam%20Antenna%20Project/?albumview=slideshow

I bought it used and the Ham that took it down did an excellent job of marking and bagging all the parts prior to shipping.  So first pointer is mark everything as it is broken down, use a marker to show tuning stops so it can go back together and work.
Scotch Bright and non conductive material brushes work great to get the spiders and bugs out of the traps.  Remember to clean and align the drain holes for proper operation.
I cleaned the slip joints with the ScotchBright pad and applied anti-ox lube to aid in reassembly and future disassembly.  Mosely sent a packet when I ordered replacement parts.
Cushcraft is now owned by MJF, so replacement parts should be available.  Check you end caps, insulators, standoffs for physical damage / cracking.
Remember to use never sieze on the stainless hardware and it's OK for reg steel as well.

I will take a look at your photos later. I'm watching my Red Sox blow what was once a 9 game wild card lead about a week ago.

All of the end caps on my traps were worn due to weatherization so I ordered 2 new ones for each trap. I don't recall using any anti-seize, what product are you using?

Here is a story I just have to tell because it is so bizarre.  Let me first preface by saying without MFJ there would be many fewer amateur products at reasonable prices. I neither love nor hate MFJ; they are just a company, and I have owned some of their products over the years just like many thousands of hams.  

Anyway I ordered a current in-rush protector for a linear earlier in the year and after a few weeks it was making an ugly buzzing sound. I called Ameritron and I was given an address in MS to mail the thing back to. They said it should be fixed in a few weeks. After about 6 weeks I called to find out what happened.  The tech asked me where I'd mailed it to as he had never seen it. I gave him the address where he was at and he was suddenly quiet for a bit. He finally said did you ship it back in a tube box? I said I have no idea what box I shipped it back in but I think I bought the box at UPS. He then said he had found it but it was in a tube box. I reply so what, it has your company's address on it and my return address and it is sealed, it is obviously a package which was mailed to Ameritron. He says it's in a tube box.  Are you telling me it's been sitting there for over a month but the box was never opened because it was in a tube box?  "It is in a tube box."  I said what the hell difference would it matter if I sent it back in a hat box, or a tube box? I already knew this circle was never going to end so I said let's forget the box it is in, when can I expect to get it back fixed? He said it would be the very next thing he would fix once he finished his current job. I got it back in about 3 or 4 days so he was a man of his word. It had to be one of the oddest conversations I ever had with any representative of any company.

What ever you do, do not said anything back to that conglomerate in a tube box - not even if it is a tube!

73

Chris/NU1O
« Last Edit: September 11, 2011, 03:37:19 PM by NU1O » Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!