ÅHOME         WA5LNL mods to MFJ 1270 for APRS Digi  ÅBACK

I. WA5LNL mods to MFJ 1270 for APRS Digi

   use:




1.*** Do not use DC plug*** for 12vdc input.

       DC should go straight in to board!

2.   12V Power:/Cut trace after power

switch and place a 1 Amp fuse in series.

Use a 1N4001 diode, cathode to ground, and a

Ferrite bead on the 12v wire.

3. Remount Q3[7805] to chassis. It

needs head sinking -runs way too hot.

4. At Q10[PTT OUTPUT], attach a IN4001 To

GND for protection from relay inductive kick-back..

5.  3 X .001 uf To GND on DIN plug. 

II. [RX,MIC,PTT] 




NOTES:




I think the  2211[U20] is a [only] SPACE 

[2200] detector, with U18 [FM-10] high-pass filter in front. The filter 

starts at about 1800 Hz and peaks at 3000 Hz, and goes to 3800 Hz. A lot of 

hiss can ride in on the signal!

The  2211 can detect as low as 2200  Hz @ 

minus 35 dB and can be solid at minus 30 dB.




de 

WA5LNL, Dink Stockert

ÅTOP

Revised: 01/01/05 05:30 PM by N5VRP, Dennis Rogers, Webmaster
Copyright 2003 by Intertie, Inc. All Rights Reserved
No use of these symbols or phrases is allowed without the express
written permission of Intertie, Inc.