Re: [IRCA] 9 Foot Longwave Box Loop (and other projects)
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Re: [IRCA] 9 Foot Longwave Box Loop (and other projects)



Hi Craig,
 
Thanks for your comments on the PVC loop experimentation, and the link to  
the loop design from VE7SL.
 
I have received quite a few comments off-list from Ultralight radio DXers  
and others, who appreciate the chance to really boost the gain of their 
simple  receivers by using one of these PVC loops. Many of these DXers were 
absent from  the radio hobby since teenage DXing long ago, and missed out on the 
extensive  box loop experimentation in the 60's and 70's. So the concept of 
getting  lots of DXing gain with a simple, large loop is something new to 
them. Even  for myself, being in the Navy from 1971-1982 (and deeply into ham 
radio after  that) made me miss out on a lot of the MW box loop 
experimentation-- so  it's quite a fascinating subject for many of us.
 
73, Gary
 
 
 
In a message dated 5/4/2009 10:01:19 P.M. Pacific Daylight Time,  
bevdxer@xxxxxxxxx writes:


Hi  Gary,

Thanks for rekindling the interest in loop antennas. Below is a  link to 
one I was contemplating building this summer. I am a bit more  motivated to 
try this since our last heavy wet spring snow of ~3ft. did a lot  of tree 
damage on my lot and took out all four of my EWE antennas. I managed  to repair 
one of them. Unfortunately, crummy weather on recent weekends  coupled with 
working weekends lately has not been conducive to fixing the rest  of the 
EWEs. One of these loops equipped with a rotor is beginning to look  good.

Here's the  link:http://members.shaw.ca/ve7sl/loop.html

73.

Craig  Barnes
Wondervu, CO


--- On Mon, 5/4/09, D1028Gary@xxxxxxx  <D1028Gary@xxxxxxx> wrote:

> From: D1028Gary@xxxxxxx  <D1028Gary@xxxxxxx>
> Subject: Re: [IRCA] 9 Foot Longwave Box Loop  (and other projects)
> To: irca@xxxxxxxxxxxxxxxx
> Date: Monday,  May 4, 2009, 9:50 PM
> Hello Again Rick,
>  
> After  adding three more turns of #18 wire to the 9' LW
> box loop, I now have  
>  567 feet of wire in 22 coil turns, and a tuning range  from
> 142 to 350 kHz. 
>  This should be OK for DX testing,  so I'll probably
> wrap it up this way. 
> It's  amazing how  much wire you need to add to get the
> tuning range a little   
> lower, on LW.
>  
> The coil turn spacing on the  loop is actually wider than
> .25 inches,  
> because  although that was the width of the wooden spacers
> used with the  circular  
> saw to cut the wire slots, I forgot to account for the  kerf
> width of the  
> circular saw blade. The actual coil  turn spacing is about
> .4 inches.
>  
> The variable  cap used in this project (and all the PVC
> loops) was a  
>  compact, 8:1 vernier drive single-section unit from the
> eBay  seller  
> "crystalradiosupply." This split-stator cap fits
>  neatly inside of a section of  1.5" 
> diameter PVC pipe, for  waterproofing the loop tuning
> system.
>  
> This LW  box loop project was essentially an afterthought,
> after the   
> construction of ten MW PVC-frame box loops of various
> sizes.  The mail goal of  the 
> project was to design and test  lightweight, structurally
> strong PVC frames  
> for  extremely large loop sizes-- a goal which was entirely
>  successful.  
> Refinements to some of the larger loops can  probably be
> made for  optimum 
> performance, and I'm happy  that Steve R. has expressed
> interest in  making one of 
>  these LW box loops according to my design, for testing 
> against his  1600' 
> long wire. Living on a residential lot of .33 acre, I
>  don't  quite have the 
> experimental freedom that he has, in  deploying sizable LW 
> antennas.
>  
> 73, Gary   
>  
>  
>  
>  
> In a  message dated 5/4/2009 12:08:52 P.M. Pacific Daylight
> Time,   
> k9ao@xxxxxxxxxxx writes:
> 
> D1028Gary@xxxxxxx  wrote:
> > The design was a basic one-loop coil  system in  a
> traditional box loop  
> > (non-spiral) design, wound  on  a PVC support frame,
> tuned by a 4-400 pf 
> capacitor  
> >  connected  directly at the coil ends.
>  
> Is that a split-stator of a single-section  cap?
>  
> > The coil windings are spaced by slots 
> > cut   in  short sections of PVC pipe, which are offset
> from the main  PVC 
> > frame  by  90 degree PVC "elbow" fittings.
>  The spacing slots are 
> separated by  
> > .25", and  are  all symmetrically cut into the PVC
> by a circular  saw  with 
> > multiple wooden  spacers of identical .25"  width.
> The  19 coil windings 
> (of #18 
> > wire)  are  then pulled tightly to  ensure optimal loop
> symmetry,  in a 
> system 
> > which  apparently  provides  excellent nulling
> capability. The 490 feet 
> loop coil 
>  > of  #18  stranded wire tunes from 167 kHz to 444 kHz
> in  the current 
> setup,  
> > but I plan to  add a few  more turns to drop the
> coverage down to  150 
> kHz.  
> > Photos of the  loop and support structure are
>  available  upon request.
> 
> I'd love to see anything you  might have, but can wait
> for  your article 
> too.I know  you must be busy.
> 
> The split-stator cap and   center-tapped loop primary
> winding improves 
> loop symmetry  and  balance.
> 
> As to the spreading of the windings, the  spreaders that
> splay  every 
> other turn up and down in  two (maybe more) sections help a
> lot in  
> increasing the  range of tuning. Let me know if photos of
> that might help   
> exp[lain what it looks like. I used wide tongue depressors,
>  but small  
> round PVC pipe sections would probably work better in  that
> big  loop.
> 
> Rick  Kunath
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