[Elecraft] OT - Twinlead and matching?

[George, W5YR]

I use 450-ohm ladderlin on three wire antennas here and use banana plugs
and jacks on each one to go into W2DU bead baluns for transition to coax
into the shack. I operate mostly at 5 watts and occasionally at 100 watts,
so there is no power problem for me. Idoubt that the "insertion loss" could
be measured at those power levels.

I would be concerned about using small banana connectors for a 1500+ watt
station, however. I think that a direct soldered connection would be the
most reliable. Depending upon the antenna, frequency and line length, a
high SWR on the 300 ohm line could place a current maximum at the line
feedpoint and really stress the connectors. Similarly a voltage maximum
could occur in which case the insulation becomes a consideration for
handling the voltage. For that reason I use RG-213 coax even at the 100
watt level since the SWR in the coax can become quite large on some bands,
and even with only 100 watts the voltage rating of smaller coax could be
challenged.

I prefer the 1:1 current or choke balun for the transition as I described
above. My three wires work well on all bands with no common-mode current
problems.

72/73/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771
Icom IC-756PRO #02121  Kachina #91900556  IC-765 #02437

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jakidz@pullman.com wrote:
> 
> Greetings:
> 
> With respect to insertion loss, are banana plugs the best way to connect
> sections of twinlead together for HF? Any better ways that are relatively easy
> to disconnect and reconnect?
> 
> Any suggestions on the most efficient means of making the transition from
> balanced 300 ohm to unbalanced 50 ohm?
> 
> Thanks.
> John, KD7OIU
> K2#1932