TODAY...SO FAR..
NH7C...569
KP3FT 559

I am keying psk-63
PAT/K8LEN

Last checked
KP3FT
NH7C
W4TTU
Not bad for a afternoon on 30 meters.
PAT/K8LEN

This upswing in activity has come just as I have upgraded my 30M APRS setup. 

I have retired my Kenwood TS-50 after 20+ years (!) of HF APRS duty, first from Los Angeles and now central Michigan. A brand new Yaesu FT-891 HF+6 rig is now doing the 24/7 beaconing/igating/monitoring duty at WA8LMF-60.   

The low-cost (USD $554) FT-891 sports a DSP-based continuously-variable IF bandwidth. This is uniquely well suited to the dual mode operation of both AX.25 and APRS Messenger MFSK16.    On conventional radios, the SSB filter is way too wide, and the traditional 500 Hz CW filter is too narrow to fully cover both AX.25 and Messenger modes at the same time.  

The 500 Hz CW filter works great for AX.25 only or PSK61/MFSK only, but it's not quite wide enough for optimum results for both at once.   With the AX.25 FSK tones set to 1600 and 1800 and the Messenger tones centered on 2100, the audio frequency span is exactly 500 Hz.  This just barely passes the center frequencies of all three tones (2100 - 1600 = 500 Hz spread),   --but-- places the lower sideband components of the AX-25 modulation process and the upper sideband components of the PSK63/MFSK16 modulation right on the upper and lower filter skirts (not the filter nose) respectively.   This adds significant amplitude and phase distortion to  sideband components at the bandwidth edges, and significantly degrades weak-signal reception.

The FT-891 has both continuously-variable selectivity AND IF shift a.k.a. "passband tuning".    I now have the FT-891's IF bandwidth dialed to 750 Hz with the passband tuning centered on 1850 Hz (mid-point of the lowest and highest tones.  This is already making a noticeable difference in my reception rate on both modes on 30 meters.  The effect of the additional "breathing room" around the lower and upper edges of the passband is dramatically visible in the waterfall displays of both the UZ7HO AX.25 "Soundmodem" and APRS Messenger.   [The full-strength of the background noise speckles in the waterfalls now extends a full 100+ Hz below and above the 1600 Hz and 2100 Hz tone freqs.]

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A reminder: My 30M APRS setup beacons 24/7, serves as an igate for both modes and provides a mapping UIwebserver display of what I am hearing off RF only (not the Internet).     Go to:

    <http://WA8LMF.net/map>    

and click the "30 meter HF" button.     Note  that the 30 meter HF instance of UIwebserver is  set to retain the icon plots for 65 minutes after the last-heard beacon from a given station.    

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Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

 
Long-Range APRS on 30 Meters HF
   <http://wa8lmf.net/aprs/HF_APRS_Notes.htm>