Hugo Upgrades the Ferrite Antenna of His CCRadio SW

 

INTRODUCTION
The CCRadioSW (aka Redsun RP-2100) is often mentioned among DXers as a powerful DX radio and in fact it is very sensitive, but it's a little bit behind famous radios like Panasonic RF-2200, CCradio Plus, Superadio 1 or 2 and some others... inspecting this radio I've found that it has a 6 inches ferrite antenna and a poor tracking varactor system (in other words, you can have maximum sensitivity from the AM band low section but the upper frecuencies from 750 Khz and up mistrack (become less sensitive), and viceversa, you need to compromise the end frecuencies to get a so so alignment.

 
 
In my quest to get my own grial (To Receive KVNS from Harligen, Tx. USA at NOON INSIDE my house of Veracruz, Mexico (distant about 600 miles) I've been doing some experimentation with varios brands of radios like, Superadio 1,2,3 Panasonic's RF-2200, RF-1150, RF-1170, RF-1180, RF-2600, RF-2800, CCradio, Sony's ICF-5900, ICF-7201 andNONE of them has achieved this goal, some of them receive this station but OUTSIDE the house, so now is the turn for Redsun RP-2100 for a little experimentation.

 
 
TRANSPLANTING A 10 INCHES ANTENNA
This was very easy to acomplish, I just took the old 6" one and change it for the 8" (See pict 2) but....The mistrack problem I've mentioned before now got worse !... I had much more signal than before but if I adjust the coil for the traditional 600 Khz the radio becomes deaf past 1100 Khz and if adjust for 1700 Khz (KVNS from Harlingen,Tx) the sensibility in the low channels is severly diminished.

 
 
After thinking some days I understood that I need more capacitance in the low channels to track with more precision and minimal in the upper band, normally this is the job of the Varactor Diode VD1 (the black one that is close to the blue preset see pict 4) but apparently this capacitance isn't enough to track so I put a second one in parallel to duplicate the capacitance (I installed underside of the board (see Pict 3) and now the radio track with more precision from 540 to 1700 Khz with some minor variations, in fact the radio now tracks better than before with the old ferrite (Are you listening Redsun Engineers ?...)

 
 
Anyway after aligning the radio (570 Khz antenna coils and 1600 Khz the Blue trimmer capacitor pict 4) I was ready to make some tests.... and the result was.... It is now the first radio to receive KVNS INSIDE my house at NOON !!! NO one radio as ever done this, it receive it with 2 bars (Pict 5 shows this). The radio is in general more sensitive across all the band at about 15-20 % 

 
 
SOME THOUGHTS
I think that I hit the noise floor with this project as the KVNS signal is a very faint one, further I'm going to take this radio to the beach far from the citiy's noises to prove this, and after that NO MORE RADIOS FOR ME !.

 

Comments

[Carlos]

Thanks for this, Hugo.

I would love to hear from anyone who could give me information on how to acquire the knowledge needed to modify the insides of my radios. I'm sure there must be books on the topic.

[jeffrey McMahon]

Ed told me about a sleeper alert: a Panasonic RF-1115 on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260609366432&ssPageName=ADME:B:EF:US:1123

[Huesby]

Carlos:
There's no book I know of but there are many webpages that talk about this like:
http://www.mindspring.com/~brucec/select.htm

http://www.mindspring.com/~brucec/dx.htm

http://www.hard-core-dx.com/nordicdx/antenna/loop/amloop.html

http://www.hard-core-dx.com/index.php
in the http://groups.yahoo.com/
check the ultralightdx group

Also I recommend buying a cheap radio to make some experiments.

[Jay Allen]

Interesting mod on the Redsun. For your particular situation you might want to look into an antenna to help you. In most cases an antenna can easily swamp minor diffrences among radios.

Jay Allen

[Wayne King]

I admire Hugo’s and others adventurous spirit in pioneering these kinds of mods. My RP-2100 definitely suffers from misalignment issues. Being inept at these kinds of things, I use a TERK passive loop alongside my Redsun, and the result is very satisfying. I hope that the upcoming C. Crane EP is a good performer with its Twin Coil antenna trimmer control. That should be interesting.

[Huesby]

Sorry but there's an important mistake and I don't want to be taken as a liar.. the article says "I just took the old 8" one and change it for the 10", it should say "I just took the old 6" one and change it for the 8"
Jeff, would you please correct the article for future repost ?
You know I'm a metric band and I don't quite grasp the english system.
Thank you all for your understanding

[Mark Heleniak]

Hugo - Good show my man!!!! For MW DX'ing I've always preferred the 2100 over the 2200, SR 1,2,3, Sat 800, 2010, etc. when adding a loop &/or a Twin-Ferrite to each. Of course the solution is bulky and not portable. You have solved that problem.

[Mobile Mark]

Thanks Hugo, Great work on your blog. Its really nice article. Thank you for posting.

[Phil Ireland]

Hi all,
I have the Australian version of this radio, the Digitech Audio AR 1747 and I've noticed a miss match between the 2 filter positions of up to 2 khz when selecting the wide or narrow filters. Anyone know a "fix" to this problem? Maybe the attaching of another varactor diode in parallel as suggested by Hugo will fix it. Would love to hear your thoughts. Otherwise it is a great radio, every bit as good as my GE Superadios 1 and 2 and the Panasonic DR22 (RF2200). Look forward to any responses. Cheers from Australia..... Phil

[John]

Do you have the manufacturer and part number of the Varactor Diode you used? There are no markings on mine, and I cannot find a service manual for this radio.

Thanks,

John