Narrow band antenna.

[Artem]

That makes no sense whatever.

Disbalance mean in-phase signal on gate 1 FETs. differencial will not
amplify this signal.

Sounds like a lot of unnecessary complexity. The one thing you repeat
is varicaps, but I don't see them.

I have. I just did now how them because this is trivial.

 

[Artem]

That makes no sense whatever.

Disbalance mean in-phase signal on gate 1 FETs. differencial will not
amplify this signal.

Sounds like a lot of unnecessary complexity. The one thing you repeat
is varicaps, but I don't see them.

I have. I just did now how them because this is trivial.

 

[Artem]

I just did now how them because this is trivial.

I did not show varicaps because this is trivial.
Sorry.

 

[Artem]

I just did now how them because this is trivial.

I did not show varicaps because this is trivial.
Sorry.

 

[Artem]

I just did now how them because this is trivial.

I did not show varicaps because this is trivial.
Sorry.

 

[Artem]

This is still a strain in language as you have done nothing to
describe what the "compensation" is for. The circuit of your
schematic is fully differential in a bridge configuration, so saying
it will not amplify still makes no sense. To offer a deliberate

It will not amplify signal in-phase signal. It's same like
differential amplifier.

I get every impression that this bridge configuration arrived from
some sense of "ground" that then drove the need for the cross piece to
the midpoint of the loop. That point is "ground", but only as an
electrical neutral to the loop. It carries no other "ground"

Yes. It's "Ground" only for bridge amplifier.

distinction and you could have as easily built a single MOSFET
amplifier rather than a bridge configuration. A split shield around

It's more difficult for me. It's looks more simply for me to build
fully symmetrical amplifier.

the loop (or integrating it into the design) would have simplified AGC
and control lines too.

You tried to incorporate some of the split shield design into this
when you enclosed the amplifier and made a socket connection, but you
defeated the benefit of the choke at the same time with a zero net
gain (the choke, as built, has no use).

I have.

They are not shown in your schematic. I don't see them in your
photos. Making them operational is adding yet more lines, although I
can see they would be necessary for your purposes.

http://img245.imageshack.us/my.php?image=d3du5.jpg

 

[JosephKK]

It's not mounted at all. But for tests I'm put this antenna outside.

Not. Just not received.

I'd personally much rather use a

I will receive QRSS at all. And I think that it would be best way is
using
narrow-band antenna -> filter -> synchronous detector.


I'm just testing. I will purchase RF generator in next week and test.
Now I have only self-oscillation frequency.

Antenna looks like working. I'm receiving a lots of Morse signals at
7.000 - 7050 Mhz. But I cant recognize any voice signal.

This is receiving signal. Looks like narrow-band enough. This is not
self oscillation. In self oscillation voltage a few volts.
http://img148.imageshack.us/my.php?image=ds0000bu6.png

This is schematics. I'm not sure that I'm correct use gual gate
transistors.
http://img210.imageshack.us/my.php?image=schbr1.jpg

I'm not sure that using shielded cable and ferrite chocks is good
idea.
http://img171.imageshack.us/my.php?image=hwak2.jpg

np0 caps.
http://img370.imageshack.us/my.php?image=capsnf8.jpg

Please see the US ARRL frequency chart here:

http://www.arrl.org/FandES/field/regulations/Hambands_color.pdf

7000 to 7050 MHz is RTTY and Morse code only. If you want voice,
probably SSB try 7125 to 7300 MHz.

 

[Artem]

Please see the US ARRL frequency chart here:

http://www.arrl.org/FandES/field/regulations/Hambands_color.pdf

7000 to 7050 MHz is RTTY and Morse code only. If you want voice,
probably SSB try 7125 to 7300 MHz.

I'm in Europe. We have only 7000....7100.

 

[Artem]

This still makes no sense. You have not described what you are
"compensating" for, and differential amplifiers amplify without
distinction to "in-phase" or "out-of-phase." If it did, you are not
using the right topology because you are using operational amplifier
terminology - the circuit is not an operational amplifier, even by
discrete components.



Nice close-up. Choking of some of the lines seems OK, but not the
coax.

http://img370.imageshack.us/my.php?image=d2eb0.jpg

Could you find in this picture choke?

So, now where is the schematic of the biasing for these
varicaps? If those two clear insulation lines are going to the loop,

It's lines from resonance loop to amplifier.

it is going to be hard to apply DC to a dead short - or does that
black shroud cover more than the varicaps?

Now my Antenna in broken. I will fix my antenna mad make a web for
schematics, software for calculation? etc.


PS: Could anyone know, What I can receive in QRSS, 7 MHz in Europe on
this
http://www.radiointel.com/review-degende1103.htm
receiver?

 

[Benj]

Hello all.
I'm looking how to make narrow band active antenna for 7 or 10.1mzh.
My idea: I will use magnetic antenna with one loop. A one-turn loop of
3.14m cupper pipe with diameter 15mm has 2.687uH. With Varicaps of
192pf it will have resonance frequency of 7MHz. I will load this LC
tank directly to Gate one of dual gate

The most effective antenna for size and gain in this range would be
the DDRR or variations of it such as the normal mode helix. They both
are single loops of copper pipe tuned at the end with a capacitor
(probably a "real" capacitor rather than a varicap would work
better.) The Helix is basically the DDRR with the ground plane
removed and the image side constructed. For more information go look
at my article in a VERY old issue of QST (May 76) and somewhere about
that time you'll also find two articles on the DDRR which are very
detailed and excellent! Note that these are often called "hula hoop"
antennas. They are basically transmission line antennas.

 

[Artem]

What material is used in the ferrite?

For transformer - low magnetic permeability (50) for chokes - high.

Does this mean the varicaps are across the loop?

http://img524.imageshack.us/my.php?image=antjy3.jpg

 

[Artem]

Unless you can be more specific, this sounds like the wrong material
(which you have not specified - do you know what you used?).

I'm use USSR ferrite 50HH.