Re: A technique to use wirewound resistors in a dummy load at HF


David Cutter
 

The CCW inverted U, particularly when the 2 ground connections are connected by a direct wire is more of a terminated loop like many others that have been around for many years, eg a Beverage or a flag.  The difference with the CCW version is that it is made for transmitting by way of a big resistor and a big matching matching transformer that will take full power. 

I read G8JNJ's article when it first came out in RADCOM and it looks quite different to me.

David G3UNA 


On 19 June 2018 at 19:02 "WA8LMF via Groups.Io" <wa8lmf@...> wrote:

On 6/19/2018 7:38 AM, Chris Moulding wrote:
How many times have you been told that you can't use wirewound resistors for RF? Many times?

On this web page I describe a technique I've developed to use the inductance in wirewound resistors as part of a low pass filter to make a 400 ohm 200W resistor termination for the Terminated Inverted U antenna.

http://www.crosscountrywireless.net/rf_load_with_wirewound_resistors.html

http://www.crosscountrywireless.net/terminated_inverted_u.html

Regards,

Didn't know this antenna design was lurking on your website until your recent post above.   It looks somewhat similar  in concept (i.e. a traveling wave vertical also terminated in a compensated 400-ohm resistor)  to the "Terminated Coaxial Cage Monopole" described here:  <http://www.tc2m.info/> .    Note that the "web page" is mostly a link to a lengthy PDF that has all the design analysis and construction details.


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