clifford wright wrote in
:
clifford wright wrote in
:
Good day all!
My latest build is a version of the VK5BR noise cancellor.
So far (using different toroid cores from those specified) I have got
about 3 "S" points of noise reduction.
I am expecting a shipment of cores from Amidon in the next few days
and will try the final version with 2 FT50-75 cores as specifid in
the later "Amateur Radio" article.
Basically though I am quite pleased with it. It means more
adjustments, but in a rural location, but with bad power line noise,
it seems to help. FYI, Don't go by the "radio communication" circuit.
It has several errors. Look up VK5BR's own site with all the
corrections. It would be very intersting to hear of others experience
with this gadget. Anyone else made one?
Cliff Wright ZL1BDA ex G3NIA
Well the unit is all operating now with the proper ferrite core
transformers.
Results vary with band but on 7 MHz I an getting about 20 dB reduction
in background QRN. 14 MHz is not quite as marked but still about 15
dB. Quite worthwhile! But one has to remember that this circuit
reduces the LOCAL noise background not ionispheric noise or QRM.
Overall I would recommend it to those troubled by electrical noise.
However I do have some reservations about the Low Q chokes used as
front end tuned circuits. I suspect that the phase shift one needs is
not as accurately obtained and it might work better with some high Q
toroids in their place. That will be tried next as soon as they
arrive. Another thing- Does anyone know of a source of adapters from
surface mountto DIL IC's. This is becoming more and more necessary as
newer chips are NOT being produced in DIL packages. I've had a lot of
trouble with a motor controller chip for an electric bicycle which was
24 pin Surface mount only.
Clifford wright ZL1BDA ex G3NIA.
There are a couple of adapter board vendors out ther. Unfortunately,
they typically cost more than the IC's. Digikey sells "surfboards", and
there are also these guys:
http://www.adapt-plus.com/products/a...smt_board.html
http://www.schmartboard.com/index.as...mttodip&id=450
Doug White