[Kenwood] 850 vs 450

[Roy Sakabu]

Hello Bob,
  I've been running a 450 for about 2 years now and just got an 850, =
although I've also had a 440, 940, 830 and 870, so I'm sort of familiar =
with Kenwood rigs.

The 450 comes with 1 - 12 khz, 2 - 6 kHz, and 1 2.7 kHz filters.  The =
only crystal filter is the 2.7 kHz filter which is in the 8.83 MHz =
position.  My 450 came with an additional 2.7 kHz crystal filter for the =
455 kHz position.  When both are engaged, the actual bandwidth is about =
2.4 kHz, but I don't really notice any difference.  To get rid of =
"monkey chatter" in SSB, all you have available is IF shift, or else you =
must buy a narrower IF filter such as the YG88SN-1 1.9 kHz SSB filter.  =
The IF shift works fine so long as you don't have anyone talking on the =
other side of the offending signal.

     The 800 and 900 series of rigs which includes the 850 has High cut =
and low cut knobs which Kenwood calls "slope tuning".  This requires =
equal width filters in both the 8.83 MHz IF as well as the 455 kHz IF.  =
The knobs move one IF relative to the other which makes the signal =
narrower on one side only.  The stock 850 has 2.7 kHz filters in both =
IF's.  I think the 8.83 MHz filter is the standard YG88S and the 455 kHz =
filter is probably a ceramic filter to cut costs.  You don't need a =
narrower SSB filter, because you can narrow down the signal with the =
High Cut and Low Cut adjustments.  The shape factor will be worse than a =
narrower filter because the actual slope of the attenuation will be the =
same as the original filter, but most people won't notice the =
difference.

     The nice thing about both rigs is that you can use any filter in =
any mode.  I've notice that when "opening up" the passband to 6kHz, I =
can get a full appreciation of what some people's audio sounds like.  So =
long as there isn't anyone else nearby, you can get really good audio =
from some stations.  With others, it doesn't matter.  I've also used =
audio DSP's to cut out the QRM with a 6kHz passband on my rig.  I've =
used the JPS NIR-12 and Timewave 599ZX and both work very similar to the =
Kenwood slope tuning or Icom's Variable Passband Tuning (PBT) function.  =
Nine times out of ten, the level of the interfering signal is less than =
the desired signal, so an audio DSP works just as well as an IF DSP.

     Even though the displays of the rigs show the limited choice of =
filter selection, you can actually put any Kenwood or Kenwood compatible =
Inrad filter width in the slot.  For example, if you are a SWL, you can =
put a YK88A-1 into the 8.83 MHz CW narrow filter position and select it =
along with the 12 kHz 455 position for great sounding AM with good steep =
skirts or add in the Inrad 4 kHz filter in the 455 CW position to chase =
AM DX  stations.

     You can get a visual picture of what slope tuning does by =
downloading the 850 manual and looking at page 33, or page 50 of the =
TS-830 manual which gives a comparison between IF shift and slope =
tuning.

     While I just got the 850, I've been studying it for quite a while =
so I am familiar with the differences between it and the 450.  Ignoring =
the additional CW features of the 850 over the 450, here are some of the =
differences that may interest you:

- Variable bandpass tuning on the 850 as opposed to IF shift on the 450.
- Variable noise blanker adjustment on the 850, only NB1 and NB2 for =
450, although I've heard that the 850 NB isn't very good, but can be =
modified.  The 850 has an adjustable NB1 level and NB2 width.
- 6, 12, 18 dB attenuation on the 850, single 20 dB attenuation on the =
450
- 850 has AGC of slow, mid, fast, off.  450 has only slow and fast (no =
off)
- The 850 allows you to monitor your TX audio, the 450 does not.
- The 850 speech processor is adjustable, the 450 is either on or off.  =
This makes the monitor function not really necessary on the 450, you =
simply adjust the mike gain while looking at the ALC reading.
- The 450 allows you to clear the RIT/XIT with the touch of a button =
because it uses optical encoders, the 850 must be manually adjusted to =
zero or turned off because it is controlled by a pot and there is no =
center detent.  This is a big issue for some.
- As with most Kenwood rigs, "AIP on" means that the preamp is OFF.  =
This should be the standard setting rather than keeping the preamp on in =
the default setup.  This will result in lower S-meter readings, but much =
fewer IMD problems.
- The 850 has the 8.83 MHz IF out in the back.  This is a wide band =
signal which can be fed into an SM-220/BS-8 or SM-230 to get a real time =
spectrum display of all received signals near your tuned frequency.  =
Sort of like a poor man's 756/Pro/2 spectrum display.  It is very handy =
at locating stations during contests or Field Day or while SWL'ing or =
seeing who is causing QRM.  The 450 does not have this output and the =
only way you can get it is to tap into it inside the radio and add a =
buffer before bringing it out.
-  The 850 allows you to add on the Kenwood DSP unit, although if you =
are going to spend that much, you're probably better off getting a used =
756Pro, 870, or TS-2000.
- Obviously the 850 is much bigger and heavier than the 450.

If I've misstated something or if anyone can add anything else, feel =
free to do so.


Hope that helps.

73
Roy
AD6ZU

_________________________Original Message____________________

Hi Guys

Thanks to all who have replied on and off list to my post looking for a =
450
or an 850.

I'd like to know what the differences in the 2 radios are. CW is not a
concern for me, but being a musician, good audio quality is.

For starters, do both radios come stock with the same filters?  I'm new =
to
all this and appreciate all the help so far!


thx

bob