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Fw: LF: Re: IGBT in 136 KHz TX?

To: <[email protected]>
Subject: Fw: LF: Re: IGBT in 136 KHz TX?
From: "F6CWN" <[email protected]>
Date: Tue, 21 Jul 2009 13:14:07 -0000
Reply-to: [email protected]
Sender: [email protected]
Subject: Re: LF: Re: IGBT in 136 KHz TX?

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...
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


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