[Elecraft] 2 dB better reception in JT65 mode

[EricJ]

There is a lot of "Just use any old soundcard, even a dongle" type of 
advice about digital modes. I went from nearly 100% CW to nearly 100% 
JT65 and JT9 on HF so I've tried a few things. I could decode down to 
about -18 or so with the built in sound card. I got an EMU 0204 for use 
with an LP-PAN and decided to try it for JT65/9. I could decode down to 
-23 and occasionally lower. I tried a SignaLink USB and can usually 
decode down to -21 and sometimes -22.

ANY sound card will work for sound card modes, just like ANY piece of 
wirewill work for an antenna. But there is a difference in sound cards 
for digital modes and there is a reason I use a TH7 at 60' instead of a 
mag loop antenna despite the fact that they both "work".

Eric
KE6US



On 1/25/2014 1:38 PM, Jim Brown wrote:
> On 1/25/2014 9:50 AM, Edward R Cole wrote:
>> The K3 is connected via the line-out to a Delta44 soundcard at the PC.
>
> I don't know anything about this sound card, but I've worked a lot of 
> JT65 and RTTY, and I found that a good semi-pro audio USB interface 
> improved JT65 decoding a LOT as compared to the sound card built into 
> my Thinkpad. With extensive testing of two computers next to each 
> other connected to the same audio, the USB interface gave me twice as 
> many decodes in a pass using JT65-HF, and gave me decodes about 10dB 
> lower into the noise (fairly often in the range of -20 to -22).
>
> I bought and tested three USB interfaces -- a Numark (about $35) a 
> Tascam (about $75), and a little mickey-mouse sort of thing. The 
> Numark and Tascam were equally good at decoding both JT65 and RTTY. 
> The little thingy worked, but was so poorly built I wouldn't recommend 
> it. The Numark has no model number, the Tascam has been discontinued 
> and replaced by one with more inputs and a higher price. I'm confident 
> that it works as well. Both the Numark and the Tascam units have line 
> inputs and outputs, and RIAA inputs. The Tascam has inputs for guitar 
> and pro mics, so it's a bit more versatile in accepting different 
> input levels.
>
> The Tascam is hooked up to my "main" K3, the Numark gets used with the 
> other radio when I do SO2R RTTY contesting.
>
> 73, Jim K9YC
>
>
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