[ARC5] Noise, power supplies and common mode v balance mode (was BC-230)

[Leslie Smith]

  Hello Neil,
  I'm with you on the balanced v unbalanced "noise thing"
  Lloyd Butler has an interesting article on this point when he deals
  with a frame aerial for 160m.
  Read the whole article, and think carefully about what Lloyd has done.
  You'll find his ideas interesting.
  BTW, if you write to Lloyd he'll go away for a day or so, and return
  with a nice piece of maths!
  It's a lot of fun!
  
  >>  The site  http://users.tpg.com.au/users/ldbutler/  <<
  >> The article:  http://users.tpg.com.au/users/ldbutler/Loop18MHz.htm

  There are other articles on noise and aerials.
  (Sorry, nothing on antennas!)

  
  73 de Les Smith
  vk2bcu at operamail.com


On Mon, Nov 10, 2014, at 13:06, AKLDGUY . wrote:
> Hi Ben
> 
> > The conventional "wisdom" is that these laptop power supplies, being of a
> switching design,  create a lot of hash and RF noise.
> 
> Yes, I thought of that too, but am still keen to try one with the braid
> of  its cable directly bonded  to the chassis of the power unit which will not only be electrically
> connected to the chassis of  the receiver, but will connect to it much more directly since the entire
> setup will mount on a rack constructed of aluminium angle. There is no such close bond in
> normal  operation and any   hash can find its way from appliances to the receiver via power
> distribution wiring.
> 
> Also, we have become fixated with 50 ohm unbalanced transmission line to
> the antenna. It's my  theory that the braid of the coax picks up radiated hash from appliances,
> so that hash voltage  exists between the braid and the inner conductor. Balanced feed should
> eliminate most of that.
> 
> My plan is to link couple the transmitter & receiver to a coil with a  split
> stator capacitor that can  be peaked up on band noise while receiving. Balanced feed taps will be
> positioned on the coil for best match. Once found, the position should hardly ever need changing
> since operation will be on the AM net frequency. Cruising up and down the band with the BC-230
> would be a pain.
> 
> The antenna here will by necessity be a very short dipole, 5 feet off the ground. I'll be happy
> with NVIS propagation to talk to the locals.
> 
> 73 de Neil ZL1ANM
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