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]   Go Down
  Print  
Author Topic: Roller Inductor noise  (Read 694 times)
W4CWA
Member

Posts: 1




Ignore
« on: October 10, 2001, 10:37:36 AM »

I have had a Vectronics 1500 antenna tuner for 4 years.  Recently I have noticed when I turn the inductor, noise/pops can be heard in the RX and the antenna analyzer indicates that the connection is intermittent.  When the inductor is not turned, the connection appears to be ok; although it can be tricky to find a spot on the inductor that make a clean connection.   I never run more than 150 watts through the tuner.

Is there something that can be done to the roller inductor to maintain a better connection when turning?

Are there some roller inductor tuners that do not have this issue?

Thanks for any help.
73,
Frank W4CWA

Logged
WB6BYU
Member

Posts: 13339




Ignore
« Reply #1 on: October 10, 2001, 11:09:32 AM »

Probably just dust or tarnish in the contacts.  A bit of elbow grease
and/or silver polish would probably clean it up.

I have often seen this problem with surplus ARC-5 roller coils.
Some roller inductors may provide more of a scraping contact which
tends to keep the contacts cleaner, but any moving contact in
any equipment will be prone to fouling over time.
Logged
WB2WIK
Member

Posts: 20611




Ignore
« Reply #2 on: October 10, 2001, 01:04:48 PM »

I've seen something similar in most every roller-inductor product (antenna tuners and amplifiers) I've ever used.  Unfortunately, it's very difficult to keep even, sufficient tension between the roller contact and the coil itself due to small dimensional variations in the coil, varying spring tension which occurs with age and use, etc.

I'd use a soft, clean cloth to wipe the inductor clean and check the tension on the coil element provided by the sliding or rolling contact.  If there's any way to increase tension, give this a try.

If you think what you're seeing is "interesting," you should see what happens when you have intermittant contact on a roller inductor in a 10 kW transmitter!  That can be quite spectacular, in terms of sparks, flames, smoke...

73 de Steve WB2WIK/6
Logged
AC5UP
Member

Posts: 3895




Ignore
« Reply #3 on: October 10, 2001, 11:56:39 PM »

Rub the moving parts down with a lint-free cloth wetted with WD-40, you might be surprised at how well it cleans up. I'm also becoming fond of using Valvoline semi-synthetic Dexron III transmission fluid as a lubricant/cleaner. About $3.00 a quart at your favorite auto parts store.
Logged

Never change a password on a Friday                
G4HZV
Member

Posts: 102




Ignore
« Reply #4 on: October 12, 2001, 01:53:55 PM »

Most of the ham tuners use roller inductors with wheel contacts. If anyone's building from scratch or can look inside before buying a boxed unit, then look for roller inductors with the rubbing block contact. These tend to be self cleaning and more reliable then the wheel contact units.
Logged
Pages: [1]   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!