(Jim #1 said;)
Hey Jim, Radio Shack has a stero version for 16.99, Part no. 270-054. It has
the wrong kind of connectors, but I will bet they have some adapters. They
call it a "Ground Loop Isolator". They also have a 1:1 audio isolation
transformer in their catalog.
73 Jim, W4ATK
> (Jim #2 said;)
> >So having read and re-read Q10241 in the knowledge base I am still
> >dissatisfied. Why do we have to live with it? It is a design defect.
> >
> >1. Okay on audio transformers but why not optical isolation? It seems
> >optical isolators would have much wider bandwidth.
>
Transformers are easier.. all passive devices for one thing, and
they've had decades to make very linear transformers with good bandwidth.
Optos require some power supply, have to deal with the issue of
putting a DC bias on the sending end, etc. All solvable, but it
takes more parts.
Capacitive coupling is yet another galvanic isolation approach.
And, there are some very cool parts from Analog Devices to do
this. But, all in all, transformers are easy.
Jim, W6RMK
---------------------------------------------------------------------
Jim;
I have decided to attack this issue, to see if I can loose some of
the amplitude of the "11 Khz DC noise" by employing isolation. Today,
I picked up both of the isolation devices that are available at Radio
Shack, as follows:
(Item #1) Radio Shack "Ground loop eliminator" Catalog #: 270-054 ($16.99)
(Item #2) Radio Shack "1:1 Isolation transformer" Catalog #: 273-1374 ($3.99)
Item #1 has no impedance specifications that I can see; It has two circuits.
Item #2 is spec'd as 600-900 Ohms, 300Hz to 5Khz response.
QUESTIONS:
(1.) Is there any advantage to using either of these devices? (I'd much rather
use the lower cost unit, as it will be easier to install.)
(2.) Is the impedance of item #1 (600-900 Ohms) acceptable?
(3.) Where do I apply the isolation? (I have been advised to insert isolation
into the LINE OUT port (cable) on the back of the SDR-1000 radio. -Is this
correct?)
(4.) Do I need to use both circuits in item #1? (Or, would I use two of item
#2?)
(5.) Per question 4; -If two of the circuits are needed, where is the
isolation to be inserted? (-Line in AND line out?)
(6.) How much can I expect the 11 Khz noise amplitude's peak to drop? (Is all
of
this WORTH the effort??? -Or, should we all simply accept this artifact as-is?)
No matter which item I use, the cables of my Delta-44 will have to be cut
or adapted in some way. -Which means that I'd have to cut off the
connectors that are part of item #1, or use a bunch of ADAPTERS. (This, or
simply
adapt the low-cost isolation transformer (item #2, above.), which will actually
be a much simpler installation.
Thank you, one and all; I appreciate your time and efforts to help us all,
with your responses.
73! -Mike- K0JTA
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