On 9/25/16 12:05 PM, Guy Olinger wrote:
On Sun, Sep 25, 2016 at 12:25 PM, Jim Brown <jim@audiosystemsgroup.com>
wrote:
On Sun,9/25/2016 6:49 AM, Steve London wrote:
What problem(s) are we attempting to solve with chokes on the 4-square
feedlines ?
Noise.
Noise, yes. Gotta give you that one, but the main reason for the 4 square
was TX gain, right? You do have listening antennas for 160 and 80? So we
have to worry about *loss*. Loss eats up gain from patterns. Loss eats up
amplifier output. Your *system* gain past your transceiver is antenna gain
+ amplifier gain *** minus LOSSES ***.
Diversion of power to miscellaneous conductor paths is almost universally
lossy and never in directions and modes desired in our attempts at
directional arrays.
So measure your output power at the system interface to the "antenna"..
put 1500 watts (total) into your 4 antennas: sum the powers at each
element (including if you have phased them so you have a negative
element). That's what commercial broadcasters do, isn't it?
The regulations don't say "amplifier output", they say
"PEP (peak envelope power). The average power supplied to the antenna
transmission line by a transmitter during one RF cycle at the crest of
the modulation envelope taken under normal operating conditions. "
"(b) No station may transmit with a transmitter power exceeding 1.5 kW
PEP. "
If I define my "antenna transmission line" reference plane at the
antenna feed points, I think that works.
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