Sent: Thursday, April 15, 2004 7:09 AM
Subject: Topband: Polarity and Phase
It requires a time delay of about 1ms to take two 500hz. tones from being
in phase to being out of phase. I can see no way that adding 180 degrees of
feedline to one of the recievers input (added delay about 3us) will cause a
noticeable change of phase in the output of two recievers.
John K9DX
>>
You've almost answered your own question here, John. Adding 3us delay to the
audio signal causes no significant phase shift, hence, no phase change. But
Tom was adding this delay to one of two RF signals, and achieved his null.
Likewise, reversing the phase of one of the detected audio signals will
cause an audio frequency null. Both are 180 degree phase shifts; one at rf
frequency, one at audio frequency; both result in output nulls.
The gentleman who achieved his 180 degree phase shift by reversing the
antenna feed leads with a relay is right on the money. This not only gives a
180 degree phase shift independent of frequency, but saves a lot of coax &
losses on TopBand! I use the relay to achieve simple in/out of phase drive
for my two transmit verticals.
Brian K8BHZ
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|