Newsgroups: rec.radio.amateur.misc Path:elroy.jpl.nasa.gov!decwrl!csus.edu!netcom.com!wa2ise
From:
wa2ise
Subject: DR1200 InterMOD reduction mod file Message-ID:
MODSDR-1200 INTERMOD REDUCTION CAUTION:THE FOLLOWING PROCEDURE INVOLVES DESOLDERING SMD (SURFACE MOUNT DEVICES).
IF YOU ARE NOT QUALIFIED TO WORK ON SMD DEVICES OR DO NOT HAVE THE PROPER EQUIPMENT, DO NOT ATTEMPT THIS MOD!
SEEK PROFESSIONAL TECHNICAL ASSISTANCE THE ORIGINATOR OF THIS MODIFICATION IS NOT RESPONSIBLE FOR ANY LOSS
INVOLVING THE PERFORMANCE OF THIS MODIFICATION CAUTION:THIS RADIO EMPLOYS STATIC SENSITIVE DEVICES.
SUITABLE MEANS SHOULD BE EMPLOYED TO ASSURE A STATIC-FREE ENVIRONMENT PRIOR TO BEGINNING WORK ON THIS RADIO.
1 REMOVE POWER AND ANTENNA FROM RIG 2 REMOVE BOTTOM COVER 3 LOCATE C-19, LEFT SIDE FRONT OF BOARD (CLEARLY
LABELED, NEAR Q3) 4 REMOVE C-19:SUCK UP THE SOLDER AND CAREFULLY PRY AWAY FROM BOARD WHILE STILL WARM 5.
SAVE THE CAPACITOR IN CASE YOU GOT THE WRONG PART! 6 REASSEMBLE THE RADIO, NO RETUNING NECESSARY This
capacitor connects D1 (back to back diodes) to the first IF line D1 is supposed to be a "limiter" Unknown
why Alinco chose to put in such a limiter, as the integrated IF chip IC-1, an MC3357, has a built- in
limiter Also, the Kenwood TM-231 which uses nearly the same layout and circuit, doesn't have such a ciruit.
While the intermod hasn't gone away entirely (I'm not done with it yet!), it has diminished enough to make
the rig usable on packet AND voice now 73 de Bill, K0ZL=============================================================================== Note:I haven't tried or verified this proceed at your own risk WA2ISE
Source QRZ: The Windows Ham Radio CDROM |
