WANTED: schematic for HF noise canceller (like the MFJ-1026)

[Jason Hsu]

Where can I find a schematic for a noise canceller for HF? I would
like to homebrew a noise canceller/preamplifier that would be similar
to the MFJ-1026. (Unfortunately, the MFJ manuals available online
don't include the schematic.)

I would particularly appreciate an explanation on how the various
parts of the circuit work (noise amplifier, noise phase shifter,
signal preamplifier, filters, etc.) and the transformer specifications
I need (so that I can use something available to me).

Jason Hsu, AG4DG
usenet@@@@jasonhsu.com
http://www.jasonhsu.com/ham_radio-technical.html

[Al]

Very good information and a schematic for a Line-Synchronous Noise Blanker
may be obtained here:
http://www.ussc.com/~turner/syn_blank.html
Al
KA5JGV

"Jason Hsu" <jaso...@my-deja.com> wrote in message
news:f7d9a152.02042...@posting.google.com...
> Where can I find a schematic for a noise canceller for HF? > Jason Hsu,
AG4DG
> usenet@@@@jasonhsu.com
> http://www.jasonhsu.com/ham_radio-technical.html

[Ed G.]

> http://www.ussc.com/~turner/syn_blank.html

This looks like a nice noise blanker circuit and I have saved it for
future reference; however, it doesn't answer the original poster's
question, "Where can I find a schematic for a noise canceler for HF." He's
talking about the RF phase cancellation device like the MFJ 1026. I'd be
interested too.

Ed WB6SAT

[George, W5YR]

So that we can better advise you, what literature resources have you
already consulted? To what other resources do you have access? What does
Google say on this topic? Will MFJ sell a copy of the schematic?

I seem to recall that a primitive noise canceller circuit appeared in one
of the amateur magazines a few years back but I do not have the reference
for you.

You might also contact AEA/Tempo who are again providing the ANC-4 unit.

73/72/oo, George W5YR - the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437

[CAM]

There was one in one of the ham publications last year. I think it was "CQ"
but couldn't swear to it. Perhaps this will jog someone's memory.
--
cheers, CAM http://www.qsl.net/w5dxp

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[Crazy George]

Jason:

I recall, perhaps incorrectly, that you graduated from an engineering school
last year or maybe this year. If that is so, you are sure not giving the
school a very good reputation. In my senior year in Physics, we were
expected to be able to do exactly what you are asking someone else to do, i.
e. draw a block diagram of a system based on the intended application,
describe the functionality of each block, and then design a circuit to fit
in each block. That was 40 years ago, actually closer to 50. Have college
standards dropped that much? All the old profs must be turning over in
their graves. :-((

--
Crazy George
Remove NO and SPAM from return address

Jason Hsu <jaso...@my-deja.com> wrote in message
news:f7d9a152.02042...@posting.google.com...

[Richard Clark]

On Tue, 30 Apr 2002 21:43:51 -0500, "Crazy George"
<muns...@attglobal.net.SPAM> wrote:

>Jason:
>
>I recall, perhaps incorrectly, that you graduated from an engineering school
>last year or maybe this year. If that is so, you are sure not giving the
>school a very good reputation. In my senior year in Physics, we were
>expected to be able to do exactly what you are asking someone else to do, i.
>e. draw a block diagram of a system based on the intended application,
>describe the functionality of each block, and then design a circuit to fit
>in each block. That was 40 years ago, actually closer to 50. Have college
>standards dropped that much? All the old profs must be turning over in
>their graves. :-((
>
>--
>Crazy George

Now don't go Crazy, George,

Jason long ago 'fessed up he did good in getting high grades without
getting too deep into understanding the theory (certainly a talent).
Support his "born again" fervor now that he cares about how things
work. There are other, unrepentant sinners who thump their test
scores at the bewildered to prove their piety. ;-)

73's
Richard Clark, KB7QHC

[Chuck Hutton]

It's not really a "noise canceller" as it is what MW and SW DX'ers call a
simple phasing box. It's job is to create two signals 180 degrees out of
phase and sum them to produce a null. In other words, it cancels whatever
arriving signal is made to be 180 degrees out of phase in the two antenna
inputs. In the case of the MFJ, one input is supposed to be a short whip or
similar whose job it is to pick up the local noise source while the other
input is the main antenna. I don't know how they do the phase adjustment
works (could be L-C, could be delay lines, could be a one of several other
ways) but the fundamental idea is the same.

It is not considered a robust front end in the MW DX'ing community. Mixing
products have been noted by a lot of people. If you want to roll your own,
I'd look at other designs. Go to http://www.qsl.net/wa1ion/ and you'll find
his web pages of presdelectors and phasing units. One of them will surely do
the job for you.

Chuck

Jason Hsu <jaso...@my-deja.com> wrote in message
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