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KWM-380 > KWM-380 Notes
personal KWM-380 notes - some fact / some opinion - but always accurate
- Very stable - PLL synthesizer
- a bit bizarre - two reference frequency (39.6 Mhz. & 455 Khz.)
- Accurately reads out to
- General coverage (0.5 to
29.999 Mhz.) - double conversion, superhetrodyne receiver...
- Continuous tuning (NO bandswitching
- receive & transmit) - a real breakthrough at the time...
- Four speed - push button
tuning (choice of 1 Mhz., 1 Khz., 100 Hz., or 10 Hz. steps)...
- I.F. passband tuning...
- Easy to read BIG (0.56"
high) red LED display...
- Excellent SSB & CW AGC
action - no need to modify (as required on most older Collins receivers)...
- No need for a separate or
remote VFO (the "norm" at the time for split operation) has
separate A/B digital VFO...
- Big heat sink - quiet operation
- no fans required for SSB & CW use...
- 100 watt output transmitter...
- Excellent, well regulated
14 VDC linear power supply is built in...
- Operates on either 105-125
VAC or 210-250 VAC 50/60 Hz. or can be optionally powered from a 12
- 15 VDC source...
- Really slick memory &
VFO operation with optional Kiron board & optional keypad - another
breakthrough at the time...
- Fairly easy to work on...
- Looks great next to my Hammond
HL-2000A amplifier (same vintage)...
- Really holds it's value
on the used market (not many manufactured - my best guesstimate - less
- SSB filter is too narrow
- 2.1 Khz. bandwidth filter...
- Surprisingly the I.F. filters
are NOT Collins mechanical filters! However, they are very high quality
crystal filters manufactured by Piezo Technology Inc.
- Bizarre passband tuning
I.F. frequency - filters are at 6.255 Khz. (can't get those at INRAD)...
- Restricted receive &
transmit audio (receive audio can be improved with careful use of passband
tuning). Spec. is 300 to 2400 Hz.
- Stock AM filter is too wide
(8+ Khz) - actually not a filter (it's an LC circuit). 5 Khz. audio
beat easily heard when tuning around the SW bands. Nearly impossible
to find AM filter (6 Khz.) option...but NICE if you can find it...
- No R.I.T. - not as big a
problem these days - as most folks dead zero beat...but rough when working
older rigs. This can be worked around by using the two VFO s but very
- No AM transmit (however,
great AM receive)...
- Not overly sensitive - no
receive R.F. amplifier - passive front end into a mixer. This is perfect
on the 160 - 40 Meter bands but not so on 20 - 10 Meters. Spec. is 0.5
uV or better for 10 dB (s+n)/n...
- Stock S-meter setting is
very stingy. Per service manual: S9 = 100 uv (can be adjusted however)!
- Generally overpriced on
the used market. As I write this (2008) you can purchase a brand new
Yaesu FT-2000 or Icom IC-756 ProIII for the average price a good KWM-380
goes for on the used market. However, if you are a Collins fan - it's
simply a "must have"...
Transmit Audio Response Test
Notes to table below:
- Careful attention was made to make sure no ALC was ever engaged during
testing at any frequency.
- Digital readout Kenwood signal generator used for accuracy - directly
fed into the rear panel audio input RCA jack.
- Some audio pre-emphasis (under 3 db) is built into the KWM-380 - peaking
around 1,720 Hz. This was ignored as I was concerned with low &
high end point roll off.
(vs. 1 Khz.
Reference 0 db)
Pretty much all energy is gone at 150 Hz. (low end) and
2.77 Khz. (high end).
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