From: Alan, VE3NNM 
Subject:Re: Help? Mod for IC-215? 
 
From: rec.radio.amateur.homebrew
Date :1998/03/10 
 
Re: Help? Mod for IC-215?
By: Jason, N1RWY
On: Thu 05 Mar 1998, 15:32:09 GMT
 
Jason was looking to put his IC-215 on 144Mhz as a packet rig.
For those who are unfamiliar with this rig, it is a 3 Watt, 15
channel FM rig for the 146 to 148 MHz band. It is portable, and
runs on 9 "C" cells, or 12 volts DC.
 
Before attempting to convert the rig to the lower end of the band,
I would advise checking the speed of the transmit/receive switch.
I looked into using this rig as part of a sampling autopatch and
found a substantial amount of delay when switching between
transmit and receive. I determined that the sampling time would 
have to be far too long to give acceptable performance as a patch,
and so I suspect that it would not perform well in a packet 
application. The TX Delay would have to be set to a fairly long
setting, and this would not solve the probem of the delay when
going back to receive. I expect that many of the received
packets would have their headers clipped off by the time the 215
settled into receive mode. I would advise making some quick checks
with the radio on a simplex frequency to see if it would give
acceptable performance as a packet station, before I got too 
carried away with converting the rig to a new frequency and 
ordering the crystals. The amount of time the rig takes to switch
is determined by C56, a 100uf cap. Altering this value may speed
up the switching to an acceptable time.
 
Concerning the frequency conversion: The European and Asian 
versions of this radio operated in the 144 to 146 Mhz region.
The diagram shows that crystal X1 is 11.155 MHz in the North 
American version, and 10.245 Mhz elsewhere. There is no mention
of a difference in the crystal formula between the two versions,
or other parts changes. I suspect that the coils and caps could
probably be tweaked into the right range without any additional
component changes. For that matter, a new trans/rec. xtals
might do the job without changing the mixer crystal. I guess some
experimenting is in order...