Interestingly, when I tested my inductively coupled 19” ferrite bar loop with the Tecsun 380 the RSSI increased from mid 20s to mid 40s for the three stations tested but the S/N remained the same at the 01-03 level (three stations that are low powered and or remote from my location; > 170 miles away, testing in late afternoon—550, 1030, and 1540 kHz)…

From: ultralightdx@yahoogroups.com [mailto:ultralightdx@yahoogroups.com] On Behalf Of D1028Gary@aol.com
Sent: Tuesday, July 06, 2010 10:37 PM
To: ultralightdx@yahoogroups.com
Subject: Re: [ultralightdx] Re: Deciphering the Kchibo Radio DSP-chip Puzzle

 

Hi Jim,

I've also transplanted a 7.5" type 61 AM loopstick into the KK-D6110 and obtained a great boost in AM sensitivity, although the poorly shielded digital board (with a tack-soldered copper shield) does allow some RF whining hash to escape to the upgrade loopstick, even when it is externally mounted. Considering the rather low price of the model, it might be worth it to install better shielding on the digital board, and see if this bargain modified ULR can chase TP's and TA's like the 7.5" loopstick PL-380's.

As for determining the best number of coil turns, the ultimate scientific procedure would be to run reception tests (using a signal generator) under controlled conditions for multiple test radios of differing coil inductances over the desired frequency range, such as was done using four different 7.5" loopstick PL-380's (300, 400, 500 and 550 uh) in the spring. This is probably unnecessary for the average tinkerer, who can get great results simply by trial and error.

73, Gary   

In a message dated 7/6/2010 5:35:41 A.M. Pacific Daylight Time, jm392c@verizon.net writes:

 

I transplanted a 7.5" loopstick wound with Litz onto the KK-D6110 and it does give it a substantial boost. The stock loopstick is easy to access, as are the solder terminals. It's disappointing, but not surprising, that this model does not contain the si4734 chip. My question to the group is: is there any way for a layman, other than trial and error, to determine the best number of turns of Litz wire?

--- In ultralightdx@yahoogroups.com, D1028Gary@... wrote:
>
> Hello All,
>
> Those DXers (including me) who had thought that the new KK-D6110 model was
> a serious attempt by Kchibo to upgrade the D96L model now have serious
> evidence to the contrary. After multiple reports of lackluster performance on
> both the AM and FM bands, a detailed investigation and disassembly of the
> KK-D6110 model has revealed that the new radio is not an Si4734 DSP chip
> radio after all, but apparently uses the same DSP chip powering the Kchibo
> KK-D680, KK-210B, KK-D202 and KK-D220 models. This certainly explains the drop
> off in AM performance relative to the D96L model, a true Si4734 DSP chip
> receiver.
>
> The KK-D6110's lower AM sensitivity specification and much lower eBay
> selling price (relative to the D96L) created doubts about this from the
> beginning, but the sole eBay seller's KK-D6110 listing (obviously translated by
> Google from the original Chinese on the Kchibo web site) certainly doesn't
> make the DSP chip identity very clear.
>
> The KK-D6110 has a DSP filter selection switch which mimics the Si4734
> models quite well (although the filtering selections are backward, like in the
> D92L), and other functions also are apparently designed to resemble the
> D96L, such as the green display light and memory operations. But AM-DXing
> performance falls well short of the D96L, and full disassembly of the KK-D6110
> brought the truth to light.
>
> The stock loopstick has a single coil with an inductance measured at 630
> uh, which would certainly be an unusual value for an Si4734-chip radio with
> no LW-band responsibility. Subtracting coil turns on the stock loopstick
> did not significantly improve X-band performance on the KK-D6110, as it would
> with a true Si4734-chip radio having a 630 uh loopstick coil. The digital
> board copper shield was simply tack-soldered at a few places, resulting in
> a slight digital whining noise bleeding through to the loopstick (which
> also affected all upgrade loopsticks, both internal and external). Removal of
> the copper shield (photo at _http://www.mediafire.com/?xy2u3wnjvyn_
> (http://www.mediafire.com/?xy2u3wnjvyn) ) revealed various IC's, but certainly no
> Si4734 DSP chip. After the earlier indications, it wasn't a big surprise.
>
> The Kchibo model numbering system apparently gives an indication whether
> the Radio is a true Si4734 DSP chip model, or not. Those models with a DxxL
> numbering system (D92L, D95L, D96L, etc.) are the true Si4734 chip radios,
> while those with the KK-Dxxx numbering system (KK-D6110, KK-D680, KK-D220,
> etc.) are not. Kchibo advertises both types as DSP radios, and the Chinese
> documentation (with rough English translations) is confusing at best. Sorry
> for any inconvenience because of this, but those DXers who had planned to
> order the new KK-D6110 model as a upgraded replacement for the D96L should
> not proceed. The KK-D6110 is a decent radio for the money, but should not
> be confused with true Si4734 DSP receivers like the D96L, PL-310, PL-380,
> PL-360 etc. The detailed disassembly photos will be uploaded to the KK-D6110
> photo album on the Ultralightdx site.
>
> 73, Gary DeBock (in Puyallup, WA, USA)
>