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Long wire antenna and Balun

PostPosted: Mon Aug 27, 2018 3:31 pm
by mike43
Further in my learning curve about shortwave radio I was reading a scanning book, and it had a section for shortwave receiving with a long wire antenna. I am not sure if the reference was about scanners or HF receivers in general but it states that having a long wire straight into the radio will overload it with noise. I knew that, so some time ago I built an antenna tuning unit. The book also said that the wire coming into the loft will pick up more noise. So from the gutter as the wire goes into the loft I joined the long wire to some RG213 (centre wire only) which goes across the loft and down into the shack to the tuning unit and then to the radio. Then it stated that noise would be further reduced if there was a Watson Long Wire Balun fitted between the longwire and the coax. Apparently they did an experiment with the Balun without the tuner and tuned to 7 MHz, there was just a band of noise. With the tuner switched in with the balun the result was amazing with most of the noise gone. So really my question to the members is would a Watson long Wire Balun or any other balun help in getting rid of some noise in my shortwave receiver. Thank you Mike.

Re: Long wire antenna and Balun

PostPosted: Mon Aug 27, 2018 4:53 pm
by m0lsx
mike43 wrote: So really my question to the members is would a Watson long Wire Balun or any other balun help in getting rid of some noise in my shortwave receiver. Thank you Mike.


A Watson balun will make no more, or less, difference than a self made balun or any other balun.
Correctly, for a SWL set up it should be a un/un, not a bal/un. But we often incorrectly refer to it as a bal/un.
The normal transformer for a SWL station is a 9:1 un/un.
The difference that a un/un makes is two fold. One you can put an earth stake onto the braid side of the antenna system & two a transformer is two separate wires wrapped around a former, so there is no direct electrical connection between the antenna & the radio. So normally noise levels are much lower.

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Re: Long wire antenna and Balun

PostPosted: Mon Aug 27, 2018 5:02 pm
by m0lsx
Bal/un = Balanced to unbalanced

Un/un = Unbalanced to unbalanced.

Re: Long wire antenna and Balun

PostPosted: Tue Aug 28, 2018 4:03 pm
by mike43
Thanks for the information Alan, I will hopefully make my own, they seem to be a bit expensive already made.