[Premium-Rx] Speakers & loops

[Terry O']

I have two loops, both homebuilt but with M1GEO "WellGood" preamps that 
I purchased direct from him. They are the best loop preamps I've used.  
 From eBay, I tried two bare PCBs and extricated a third from an 
MLA-30.  I also have an old R. W. Burhans loops amplifier he wrote up in 
an ancient issue of Radio Electronics magazine.  None come close to the 
M1GEO preamps.

As M1GEO notes on his web page, 
https://www.george-smart.co.uk/projects/wellgood-loop/  there are now 
Chinese and Russian clones on eBay of his preamp with inferior circuits, 
some actually advertised as WellGood.  The WellGood is a reverse 
engineered version of the now unavailable Wellbrook loop. So now others 
have cloned the clone, but without developing a proper circuit as M1GEO 
did.  Buy the M1GEO instead of the clones.

One of my loops is 6 feet off the ground in the backyard at a point 
furthest from any power lines and atop a CDR rotor (which is overkill 
for a lightweight loop).  It has an 8 foot ground rod directly 
underneath it and common mode chokes on the feed line. These chokes are 
essential in my urban location to attenuate noise that tries to 
accumulate and ride down the feedline into the radio room.  I also have 
common mode chokes at the entry point to the house where all my 
feedlines pass through GDT arrestors mounted on a metal plate grounded 
with two 8' ground rods, 8 feet apart.

The other loop was on the roof 35 feet off the ground. Naturally the 
ground is a long way away.  It also has common mode chokes on the 
feedlines.  The roof loop is at the moment in the house for the winter 
getting rebuilt into a huskier form.  I'm also changing it to use a 
single turn of 10 gauge Litz wire.

Performance of the two loop is similar with no huge differences despite 
the large difference in height.  Both loops present a lower level signal 
to the receiver with a higher signal to noise ratio.  In places where my 
long wire antenna shows resonance with an MFJ-259, the long wire works 
better than the loop.  But the broadband characteristics of the loops is 
unbeatable, as is the ability to turn the null toward local noise 
sources and interfering signals.

I also have a third loop built as a portable around a Chinese MLA-30 
preamp from eBay.  It is almost as sensitive as the WellGood.  But, at 
my QTH, it is acutely susceptible to intermod from AM broadcasters even 
though the closest transmitting facility is 6 miles away.  It is also 
limited in portable use where I use an SDR because I can't get it 
isolated enough from the laptop (a.k.a. digital noise generator).

As for speakers, I use a variety of Wohlers, as described in recent 
thread on watkins-johnson.groups.io.  Many Wohlers are popping up 
inexpensively and are quite useful in a room setup.  I found my first 
AMP-2 at a hamfest for $10.

73
Terry O'
WB9GVB


On 12/30/2023 7:26 AM, Michael Melland via Premium-Rx wrote:
> Hi folks,
>
> I’m back on the list after a number of years off, having rehomed my radios during a move and build.  The shop and a man room is done so I figured it’s time to pick things back up.
>
> I’m curious what speakers you’ve found to work best with your receivers ?  In the past I used single Radio Shack stereo speakers… nothing fancy. I just acquired a WJ 8711A and will be setting it up with a bit more thought than normal ,lol. Thinking of trying a loop antenna… always used long wires in the past. Your thoughts on loop use would also be helpful.  I wish the archives were searchable… I’m sure they contain useful info…
>
> Mike, W9WIS
> Sent from my iPad
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