On Thu, 14 Aug 2014 18:24:05 EDT, DrTeeth wrote:
Is it worth paying a high price for sa supposed quality plg or can
equally used the much cheaper ones?
Been QRT for over 25 years and should be on the air in a few weeks
with a FlexRadio 6300
Ummm... a Flexradio 6300 retails for $2500 and you're trying to be
cheap on coax connectors? That's 0.1% of the retail price for a
silver plated and PTFE connector. I'll play along, but your question
seems a bit absurd.
There are many things wrong with the PL259, few of which will have an
effect on your HF operation.
1. The PL259 is not 50 ohms and therefore produces an "impedance
bump" on the line. You can see it with a TDR (time domain
reflectometer). However, unless you're using it at microwave
frequencies, it won't have any effect on your operation.
2. The PL259 plating has an effect on PIM (passive intermodulation
distortion) where the non-linearities of some plating material, or the
insufficient thickness of the plating, can cause mixing. Also,
magnetic materials used in the connectors are a problem. Nickel
plating is the worst. White bronze or Nexcote are the best. Mixing
plating types is really bad. Unless you're running full duplex on HF
(unlikely), or listening for really weak signals at VHF/UHF and higher
frequencies, it's unlikely to be a problem.
3. The PL259 is a PITA to assemble correctly. You have a chance of
getting it right with a crimp connector, but the conventional PL259 is
an ugly mess to assemble. This is fairly accurate. Note the vise
grips and butane torch:
http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/SolderCoax.htm
Despite such methods I still see broken jumper cables with rotating
connectors. Even if it's done correctly, they still tend to fall
apart. Extra credit for nickel plating that is difficult to solder.
4. The necessary insulation comes in a variety of materials. Nylon
is the worst as it's hydroscope (absorbs moisture). Bakelite is
brittle, but deteriorates over time. Some kind of white stuff looks
ok for RF, but melts easily. PTFE (Teflon) is probably the best and
does well at high power levels.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558