Hello Laurence and all!
I use
a two turns rx antenna, it works quite good (more directivity). And it
are this type of aerial which has just given me the idea of trying a
large coil in TX.
Wires in parallel are a very good idea to reduce
losses.
The problem (I think) is the Q of this aerial. It
is necessary to build an automatic system (PID) to
compensate the drift because the aerien is very sensitive to the
environment variations. This is not easy because power is
high!
Two advantages: smaller aerial and bigger
directivity.
Disadvantage: More copper in air (heavy!), really
in case of problem more important fire hazard. Without counting that the
horizontal polarisation of the field is forgotten.
Conclusion: It is again necessary to
think...
VY 73: Jeff
(PS: Ferrites are N67 and not N87!)
----- Original Message -----
Sent: Tuesday, July 21, 2009 5:47
AM
Subject: RE: LF: Re: IGBT in 136 KHz
TX?
Jeff - The "turns" of the mains WD2XDW loop were just
distanced parallel loops running in roughly the same plane to reduce the RF
copper losses and open up the bandwidth a bit - . I did try a couple of
"turns" but never managed to get the ommppff field. Interesting given the
fact that some people use 2 turns on their K9AY's successfully -
All the loops ends up welded together on lugs and
attached to the tuner. Ive just overhauled the tuner ready to put on
line for WE2XPQ but it will be running lower power for a while as I dont
want to start a forest fire in Alaska!
Back home in KL7 on
August 14th again...just need time...
laurence
BY3A-KL1X
Tanggu China 34degC
We2XPQ/ x Wd2XDW Wasilla
AK
Subject: Re: LF:
Re: IGBT in 136 KHz TX?
Hello Markus and Rick!
I have only just acquainted myself with your
messages.
(Just going out from hospital, big blood pressure
problem...)
Thanks a lot for precious information, of
what make fun still!
I recovered some ferrites N87 types which
should work in 137 KHZ.
Another subject interests me, it is the
possibility of transmitting with a big spool of several turns (a bit as
WD2XDW). But EIRP is much weaker than with a vertical aerial, then it
is necessary to "push more" in power!
Thanks in advance!
- 73: Jeff / F6CWN
Windows Live™ SkyDrive™: Store, access, and share your photos. See how.
