|
New to Ham Radio?
My Profile
Community
Articles
Forums
News
Reviews
Friends Remembered
Speak Out
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
|
|
You can
write your own review of the Johnson KW Matchbox.
|
OE5OHO
|
Rating: 5/5
|
Aug 22, 2000 07:57
|
Send this review to a friend
|
|
Best Tuner ever built...
|
Time owned: more than 12 months
|
|
This little piece of craftsmanship is working perfectly for my innercity flat. I´m using about 30m of 240ohm old TV-cable to feed an indoor dipole. The cable passes all things it shouldn´t, like lightning conductors, metall roof parts. Despite this I can tune my dipol on every band from 80 to 10m (except 40m, where I guess some interaction with the house is happening). Worked a couple of DXpeditions with only 100W - and no TVI for all my neighbours... IF YOU see one at a ham fair - take it!
|
|
K7NA
|
Rating: 4/5
|
Sep 16, 1999 23:51
|
Send this review to a friend
|
|
One of the VERY Few Matching Networks that has a t
|
Time owned: unknown months
|
|
That's right, folks! Go ahead and use your unbalanced, singled ended output MFJ's and Ameritrons, with their built-in 4:1 baluns. But please do check to be sure you have true balanced output with equal currents in both sides of your tuned feeders on all bands! Chances are you don't! No wonder you are experiencing TVI, telephone interference, computer hash! Try using a link coupled, balanced output matching network. The Johnson does a fine job of providing equal currents on both sides of the feeder. It has a rather limited matching capability. There are modifications that can be made such as adding a small variable capacitor in series with the cold side of the link to ground, among others. Take a look at Richard Measures' (AG6K) article in the Feb. 1990 issue of QST for an explanation of why 4:1 baluns do not perform well over a wide variety of input loads. The Johnson Matchbox can often be found at swap meets and ham fests. Next time, take a closer look at this venerable but still serviceable matching network!
|
|
If you have any questions, problems, or suggestions about Reviews,
please email your Reviews Manager.
|
|
|
|
|
