A short technical review of the DR-235T MKIII mobile radio by John W1GPO

The Yaesu 8900R radio that was similar to the DR-235T MKIII with identical 
+/- 9.2 kHz modulation acceptance bandwidth and the IF passband also being 
1 kHz off center. However, the DR-235T MKIII had excellent modulation 
symmetry, unlike the poor symmetry on the 8900R. The DR-235T MKIII deviation 
levels came set too high at +/- 7kHz for voice and over 1 kHz for CTCSS. For 
wide-band FM, first adjust the voice deviation pot, VR107, because lowering 
it also reduces the CTCSS deviation, then adjust VR108, labeled DCS Deviation, 
as it also adjusts CTCSS deviation. This adjustment is REALLY touchy - not 
much of a twist changes the DCS/CTCSS deviation a lot. This may be the reason 
there were problems with slow CTCSS action in some radios. Also, the CTCSS 
deviation is greatly affected by the CTCSS frequency - the higher the CTCSS 
frequency, the greater the CTCSS deviation. CTCSS decode with a +/- 0.65 kHz 
deviated signal was as just as fast as any Motorola radio, except slower to 
open and much slower to release at +/- 0.1 kHz CTCSS encode deviation. I did 
not test DCS, as even in Motorola radios, is a bit slower to pick up. Also 
it really does not buy security, as these radios, as well as some others, 
will identify an unknown transmitted DCS code. One really good feature with 
the DR-235T MKIII, is its 2.5 PPM frequency tolerance. In fact, when the 
radio, as received from the factory, was left to warm up for 30 minutes, the 
Tx frequency was within a few Hertz of dead on!