[ARC5] Using WSJT-X with R-23 or BC-453B

[Christopher Bowne]

If you think the mixer hetrodyne oscillator is stable, and the BFO is the culprit, try injecting an external BFO signal from a good quality signal generator or synthesizer.  That way you can take advantage of the observed better sensitivity of the command receiver.  I currently use a Rockland 5100 synthesizer as a BFO for my Scott SLRM not because of a stability issue, but because of the very low BFO injection level of the Scott's internal BFO.

Sent from my iPhone

> On Nov 2, 2017, at 09:57, J Mcvey via ARC5 <arc5 at mailman.qth.net> wrote:
> 
> The drift issue is definitely due to the receiver, because I have two other radios that I can switch in and out to check the traffic. The modern radios do fine with several successful decodes per interval ( yes I use D4 for synchronization) .
> Bill suggested that the BFO may be the culpret on the BC453 and maybe the others as well. In fact,  the BFO oscillators are a bit flakey.
> I pulled the BFO coil can apart on the R-26 and tried cleaning the variable cap rotor contactors, thinking it may be some kind of corrosion issue ans also replaced the 200pf coupling cap, It;s ok for CW , but I can actually hear slight pitch variations from time to time, so there are  more minute fluctuations that I don't hear.
> 
> The waterfall indicates a tilt drift left ( decrease in f) which could be caused by an drift upwards of the heterodyne 
> frequency.
> There isn't much to the BFO LC circuit to go bad , just air variables and the coil. I even re tightened the internal ground lugs and resoldered the joints. Still not very stable!
> 
> I have an old military signal generator that once warmed up, is quite stable, so stability can be achieved.
> I wish I knew how to do it with the ARC BFOs!
> Any suggestions?
> 
> On Thursday, November 2, 2017, 5:48:45 AM EDT, Peter Eijlander (PA0PJE) <pa0pje at xs4all.nl> wrote:
> 
> 
> http://physics.princeton.edu/pulsar/k1jt/WSPR_3.0_User.pdf
> page 5, second paragraph:
> 
> Each decoded WSPR signal produces text showing the UTC, measured 
> signal-to-noise ratio in dB (in a 2500 Hz reference bandwidth), time 
> offset DT in seconds,measured frequency in MHz, drift rate in Hz/minute, 
> and the decoded message.Time offsets greater than about ±2 seconds 
> indicate a significant timing error at transmitter or receiver, or 
> possibly both. For best performance your computer clock should be kept 
> accurate to within ±1 second.
> 
> Apparent frequency drifts greater than ±1 Hz per minute can usually be 
> traced to the transmitter, and should be corrected if possible. Of 
> course, receiver drifts could also contribute to a measured drift — but
> they are easily recognized because nearly all signals will appear to 
> drift by the same amount.
> 
> Page 22 item 3:
> 
> 3. Is your receiver drifting in frequency? If most WSPR traces slope 
> either upward or downward in the spectrogram, the receiver is probably 
> drifting too much. Try waiting half an hour to see if it stabilizes.
> 
> 73,
> Peter
> 
> 
> Op 2017-10-29 om 15:37 schreef J Mcvey via ARC5:
> > Has anyone been able to get successful WSPR decodes using either of the beacon receivers? For me, it appears that they have too much drift to allow the algorithm to work properly.The waterfall has a slight sideways tilt!.Even after an hour, they will not yield any stations although they are audibly there.
> > It's a shame, too, because I think the beacon receivers seem to have better sensitivity on 630M than my YAESU or converted dongle SDR, both of which do produce good decodes.
> > I swear I hear more stations using the BC453 and R-26!
> > 
> > 
> > 
> > 
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