Re: #bitx40help BITX40 LSB Winlink #bitx40help

M Garza <mgarza896@...>
 

Daniel,
Your understanding is correct.
We have a 12 MHz IF.  5 MHZ BFO gives us a 7 MHZ LSB signal and a 19 MHZ BFO gives us a 7 MHZ USB signal.  The IF & filter are constant.  In our case, the BFO is moved to either side of the ladder filter to change side bands.

Marco - KG5PRT 

On Tue, Mar 27, 2018, 8:47 AM Daniel Crane <danjamitch@...> wrote:
Thanks Joe.  Yup, Allard's sketch.  That's what I got from Marco and Gordon's posts.

Just to recite my new understanding, for those like me whose facility with superhet design strays just into and out of visibility -

The magic is in the ladder/BFO combination, which shears off the carrier and unwanted sideband, while passing the wanted sideband.  This is not touched in Allard's sketch.  So...  if you use, say, a 10MHz IF, then  3 MHz BFO will get you 7MHz LSB and a 4 MHz BFO will get you 14MHz USB.  Of course you have to filter to make sure you have signal content where you want it to look.

To get 7MHz USB you need a BFO at (drumroll) 17 MHz.  You have to point the ladder at -7Mhz in order to get the mirror image sideband.  Am I right?

Dan

On Mon, Mar 26, 2018 at 9:49 PM, Joe Puma <kd2nfc@...> wrote:
I thought the b40 has USB with the latest version Allard’s? sketch. I’ve used my bitx40 with wsjtx which needs USB too. Winlink should work for you. 



On Mar 26, 2018, at 8:39 PM, Daniel Crane <danjamitch@...> wrote:

I am trying to find a way to connect to Winlink with my BitX40.

I have one of the last Bitx40's shipped, in late November, just before the ubitx started to arrive.  Another fellow whose name I cannot recall got one at the same time and had a lot of difficulty getting it going.  The group here helped him along and over a period of weeks got him up and running.  Just at the conclusion of that process he reported that he had that day made successful Winlink connections.  From the context and timing he would not have converted his BitX 40 to USB.

Does anybody here know if it is possible to connect to Winlink on lower sideband?  I've tried WINMOR, ARDOP, and VARA, but no joy.  No RMS answers my calls.  I have made a number of PSK-31 QSO's between here (LA) and stations as far away as Washington state, so I know my radio works.  I decode RTTY and Olivia as well.

I posted this question on the Winlink group and got the school answer, "Winlink requires USB".

I uptune so as to match 1500Hz center frequencies.  And I uptune 700Hz more because my BitX isn't calibrated.  Occasionally I get lucky and see an RMS engaged  in a session and center that signal. I patiently tune in 100Hz increments.

But still no joy.  Any ideas, other than move on to USB?

Thanks/Dan
KM6GRV




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