In article ,
Jeff Liebermann wrote:

Now working on an MFJ-259A, which looks like the usual blown diode
problem:
http://802.11junk.com/jeffl/MFJ-269-repair/

"Of course, when I got it back together (for the 2nd time), I found
the reading to be erratic and intermittent. It took a while to
discover that the owner had somehow spread the gold center contact
leafs in the type-N connector and my adapter wasn't making
contact."

My repeater cohort and I have seen quite a few N connectors which were
damaged in precisely this fashion.

One cause: some N-connector adapters floating around out there have
center pins which are either too large in diameter, improperly
tapered, or which protrude too far "forwards". I suspect that male N
connectors, if improperly installed, can have the same problem (the
pin is pushed too far into the connector).

In either case, (over)tightening such an N-male connector onto an
N-female will cause it to make excellent contact... once... as the pin
splays the female connector's contacts outwards. Subsequent
connection attempts with a properly-configured N male won't make good
contact.

In a pinch, you can try pinching the contact fingers back in, but it's
nigh-on impossible to restore them properly. Better to remove the
damaged female connector and replace it. Then, check all of your male
N connectors to make sure the center pin has the proper taper and is
in the proper position. A center pin with a rounded blunt end (rather
than a properly-tapered point) is Trouble.

This turned out to be all that was wrong with a defective TK-981 I
picked up at the De Anza ham flea market last year. Cut off the N
connector, solder-and-crimp a new one onto the pigtail, and it checks
out fine.