This diagram explains the issue somewhat:
http://kaitousa.com/KA31.htm

The tuner is a small plastic enclosure including the power switch, tuning dial, and the battery bay. It has a wire connected directly that is around 21 inches in length, and the tuner has a jack on the other side. The jack on the tuner is the same as the jack on the antenna, and a much longer wire goes between them.

The diagram on Kaito's site indicates that the shorter, directly-connected wire should make the connection to the radio (or optionally the short wire with the black and white clips), and the long wire should go between the tuner and the antenna.

This configuration allows the antenna to be hung wherever it will perform best, while positioning the tuner close to the radio for convenient operation.

Degen DE31 'portable' Shortwave "Active" Loop Antenna
 

wrote:
The internals of the DE31 antenna are discussed (and shown) he
http://www.drmrx.org/forum/archive/i...hp/t-1210.html

Thanks!

That is exactly what I was looking for.

Regards,
NEO





N9NEO wrote:

Yes, I would think that you would want the variable capacitor close to
the loop too. I think what we have here with the loop is just an
inductor...

Damned if I know what is in the unit by the radio. I suspect a
variable capacitor and a jfet like a mpf-102. I don't think a
varactor diode kind of setuup will tune such a broad range. I will
take my unit apart one day soon and report back to group if anyone
interested.

regards,
NEO

Degen DE31 'portable' Shortwave "Active" Loop Antenna
 

Telamon wrote:
In article ,
weatherall wrote:

pure Wrote:
What a piece of CRAP this antenna turned out to be.......almost the
price of the radio itself !!!

This is why it's crap:

1) the reception is WORSE with the antenna, than using the whip
antenna on my degen radio, model DE1102 !!! I actually get the signal
properly, and can listen to the program with the radio, but then the
show disappears completely if Iuse the external DE31 antenna!

2) the batteries AAA inside the antenna, to power it, run down pretty
fast. I recharged a pair just before, and they were run down 2 or 3
hours later, when I gave up.

3) it's not clear how the de31 can give a better signal, unless you're
in a manhole, in a military bunker, underground and you need to have a
connection to the surface 5 m away. This would be the only conceivable
use for this antenna.

What a huge waste of money, this de31 !!!

I had problems with my DE31 until I figured out that the wire between
the antenna and the radio was backwards. I had the tuner close to the
loop at first, and it basically eliminated the signal. Maybe most
people don't make this mistake though.

I'm not familiar with this particular model but I would think that you
would want the tuner near the antenna.

I use duracell alkaline AAA batteries in my DE31 and they have been
there since last winter. They're still working.

Rotate the antenna so that the hole faces the direction of the
transmitter. If plugging the antenna in seems to provide poor
reception, try clipping it to the whip with the white clip, and clip
the black clip to a ground wire.

The "hole" in the antenna is the null or that which will provide the
weakest reception of a station. You want the edge of the electrically
small loop pointed at the station you want to receive. You point the
"hole" or null at a station or noise source you do not want to hear.

--
Telamon
Ventura, California

Telamon - For AM/MW Frequencies this does work well
-but- For the higher Shortwave Frequencies positioning the
Loop for the least local Noise pick-up is the preferred MO.

iane ~ RHF

Degen DE31 'portable' Shortwave "Active" Loop Antenna
 

Good thread, and Nice call Telamon! The tuning mechanism by the radio
sends a voltage up to the unit by the loop. The unit by the loop has a
varactor diode inside. Sombody over in the other group said there is a
step up dc-dc converter to get from the 3 or so volts supplied by a
pair of AAA batteries to a voltage that the diode can use. I didn't
realize that a varactor diode could swing more than a few pf, so
thought that they wouldn't be very useful over the complete range the
thing is supposed to tune.

regards,
NEO


weatherall wrote:
Telamon Wrote:
I'm not familiar with this particular model but I would think that you
would want the tuner near the antenna.


This diagram explains the issue somewhat:
http://kaitousa.com/KA31.htm

The tuner is a small plastic enclosure including the power switch,
tuning dial, and the battery bay. It has a wire connected directly
that is around 21 inches in length, and the tuner has a jack on the
other side. The jack on the tuner is the same as the jack on the
antenna, and a much longer wire goes between them.

The diagram on Kaito's site indicates that the shorter,
directly-connected wire should make the connection to the radio (or
optionally the short wire with the black and white clips), and the long
wire should go between the tuner and the antenna.

This configuration allows the antenna to be hung wherever it will
perform best, while positioning the tuner close to the radio for
convenient operation.




--
weatherall

Degen DE31 'portable' Shortwave "Active" Loop Antenna
 

Holy Cow!

The data sheet for the varactor diode claims less than 30pf to over
400pf with a 7v swing and Q of 200. Nice part - amazing part - how do
they fit all those plates inside there?

73
NEO



N9NEO wrote:
Good thread, and Nice call Telamon! The tuning mechanism by the radio
sends a voltage up to the unit by the loop. The unit by the loop has a
varactor diode inside. Sombody over in the other group said there is a
step up dc-dc converter to get from the 3 or so volts supplied by a
pair of AAA batteries to a voltage that the diode can use. I didn't
realize that a varactor diode could swing more than a few pf, so
thought that they wouldn't be very useful over the complete range the
thing is supposed to tune.

regards,
NEO


weatherall wrote:
Telamon Wrote:
I'm not familiar with this particular model but I would think that you
would want the tuner near the antenna.


This diagram explains the issue somewhat:
http://kaitousa.com/KA31.htm

The tuner is a small plastic enclosure including the power switch,
tuning dial, and the battery bay. It has a wire connected directly
that is around 21 inches in length, and the tuner has a jack on the
other side. The jack on the tuner is the same as the jack on the
antenna, and a much longer wire goes between them.

The diagram on Kaito's site indicates that the shorter,
directly-connected wire should make the connection to the radio (or
optionally the short wire with the black and white clips), and the long
wire should go between the tuner and the antenna.

This configuration allows the antenna to be hung wherever it will
perform best, while positioning the tuner close to the radio for
convenient operation.




--
weatherall

Degen DE31 'portable' Shortwave "Active" Loop Antenna
 

More thoughts on the placement of the variable capacitor

- A parallel resonant circuit has fairly large currents sloshing back
in forth between the caps and the inductor. Of course in a loop
antenna arrangement where we are dealing with microvolts the currents
aren't so large, but, any resistance in the path (such as a long thin
cable) between the inductor loop and the variable capacitor will reduce
the circuit's Q. So an arrangement using a potentiometer by the user
and a varactor diode by the loop end is perfect.

Regards,
Yzordderrex

Degen DE31 'portable' Shortwave "Active" Loop Antenna
 

In article .com,
"N9NEO" wrote:

More thoughts on the placement of the variable capacitor

- A parallel resonant circuit has fairly large currents sloshing back
in forth between the caps and the inductor.

Snip

We don't allow that kind of talk around here, that's
rec.radio.amateur.antenna trash talk.

--
Telamon
Ventura, California