[Lowfer] Der Bigger Loop

[Dale Parfitt]

Mitch Powell wrote:

>  At what point does increasing loop
> > diameter
> > not result in meaningful increase in S/N?.
> > There is a condition on 10 GHz EME where moon noise becomes the limiting
> > factor
> > on a receive system's noise temperature.Bigger dish does not help.
> >
> > Dale W4OP
>
> Dale - just a quick copy of an earlier e-mail I sent as brief answer to the
> same question about untuned loops -  Based on nothing more than using them
> for the past seven-eight years. I think John might be saying the same thing.
>
> Q.  What magnitude of increase do you see between the various sizes of
> loops, like 4', 6', 8', 12', etc.?
> A.  I had great results with the 6 foot hard-line. It was about the time of
> the original article by Mitchell Lee. I copied HAO ( French Polynesia ) and
> Easter Island, and NDBs coast to coast.  The other extreme is the 12 footer
> - shown on the web site. It's a brute to handle - lifting over your head at
> the top of the pole - while trying to drop it on the pipe ! !
> It is very sensitive, very directive and I think it approaches ( or has
> passed ) the law of diminishing returns. When I switch to the 7 footer - I
> hear the same signals, but with less ambient noise level.
> I would not build the 12 footer again. I would stop at 7 - 8 feet. It is
> more than adequate, unless you are fortunate enough to have a great, quiet,
> rural site.
>
> 73
> Mitch
>

Thanks Mitch,

I should have better documented my 3' loop results. Even had I done that though,
comparisons would be difficult right now because of the hi QRN level.

I may have expressed some concern in an E-Mail to you that perhaps in modifying
the original Burhans balanced amp by replacing the TL004 transformers with the
bifilar FT50-75's that the LF response has suffered. Until I build the amp with
the mouser transformers I will not know unless I model it in Eagleware's Genesys
or stick it on the network analyzer (not likely now that it is in the air).
Currently it is only 3-4' off the ground as I have to move the tower section it
normally sits on so the loop will clear trees. I guess that raises another
question that Dex had briefly commented on- that being that loops seem to be
less affected by close in trees than are loops? I have nothing to compare it to,
but it is in a forest.

Dale W4OP