To add to Telemon's' reply:-
there are two issues:
1.] I'm not sure is you are using the right antenna jack. The one for
SW is marked SW FM and needs a PAL jack to connect. The other input is
for bare wires to be connected for MW only and cannot be disconnected
(it won't work on shortwave).

2.] As Telemon said, you may also have shorted your RG58 coax and that
might be the reason you are getting the poor result. It's easy to
checkout with an Ohmeter, otherwise just check the connections
carefully. Also, you can't just connect a longwire to a coax without a
matching transformer/balun. A longwire has an impedance of from 500 to
1000 Ohm's, whilst the RG58 is 50 Ohm's, hence the necessity to match
the two, otherwise you are going to get signal loss.

Good luck!

John Plimmer, Montagu, Western Cape Province, South Africa
South 33 d 47 m 32 s, East 20 d 07 m 32 s
RX Icom IC-756 PRO III with MW mods
Drake SW8 & ERGO software
Sony 7600D, GE SRIII, Redsun RP2100
BW XCR 30, Sangean 803A.
Antenna's RF Systems DX 1 Pro Mk II, Datong AD-270
Kiwa MW Loop, PAORDT Roelof mini-whip
http://www.dxing.info/about/dxers/plimmer.dx

On Mar 5, 6:13*am, wrote:
Hi,

I have a Redsun RP2100 and have been trying different antenna setups
to try to get reception here in S Korea. *I have had a little success
but it hasn't been great. *I am able to get reception on SW1 but SW2
and SW3 have virtually nothing when I listen at night. *I have a
question about my RP2100. *Recently I attached a longwire antenna to
the radio through the external jack on the back. *There was no
noticeable improvement in reception for SW2 and SW3. *But, when I
changed the switch on the side from external to internal and touched
the whip with my finger suddenly the longwire worked from 10000 -
30000. * If I unplug the longwire from the external jack and continue
touching the whip the reception in gone. *If I connect the longwire
directly to the whip, again the reception is great. *This is all while
the switch is set to internal antenna. *Is the external jack is
broken? *Strangely, I have tried using a small Degen DE31 with the
external jack and the switch set to external and it seems to work(but
not on SW2 & SW3). * My knowledge of antennas is low and perhaps I am
doing something wrong. *I am using 20m of 50 ohm RG-58 coax lead.
Unfortunately I can't get the antenna any closer to my house and
shorten the coax. *I am going to try grounding the antenna next.

On a side note, does anyone know where you can receive service for a
Redsun product? *I have tried writing to many different email
addresses and have had no response.

Thanks for any help
Regards

Garth