Re: MXM 30 Meter Xcvr Kit


From: Geoff Schecht (
Date: Sat Jul 22 1995 - 14:35:17 EDT

Hello Gus:

>Does anyone have any comments they would like to share
>with me about the SuperRig from MXM?

I have one of the older SuperKits. My only major complaint about it is
the fact that a lot of the holes in the PWB were drilled off-center to
the point that the mtg. pads weren't usable. It took considerable
effort to get the component leads to contact the PWB lands in several
spots. The documentation was adequate for me since I'm very good at
building and fixing just about anything electronic (and obviously not
too proud to brag, either!) but someone without much electronics
experience would definitely need help. I got a schematic and a Xeroxed
assembly guide but this was most definitely *not* a Heathkit.

If Bruce is selling chassis, I'd defintely recommend getting one since
mounting this in a blank Bud Box took a lot of drilling, sawing and
filing! The vernier cap that Bruce modified for the RX VFO is a pretty
good quality unit; use the mounting holes on the bottom of it to
secure it to the chassis as close as possible to the RX VFO section of
the PWB. I replaced a number of the parts in the kit with higher grade
components but that's only because I had them on hand.

Watch the TX oscillator on a scope or spectrum analyzer when tweaking
it. Mine had a tendency to mode-hop to the third harmonic when the
slug was adjusted to one extreme.

The ceramic filter in my unit is not too great for CW use (NTK LF-B4
+/-2kHz/-6dB & +/-7.5kHz/-40dB. The ultimate rejection is only 27dB,
too. I remember Bruce telling me he was having fits getting Murata
filters at the time I bought my kit. Considering the relatively modest
initial investment in the kit, you can afford to replace this filter
with a better one.

 I'd recommend a CFS455J ceramic filter from MuRata (+/-1.5kHz/-6db &
+/-4.5kHz@-80dB <asymptotic> with 60dB ultimate rejection 100kHz from
center). It'd be a wire-in,the CFS455J's a lot bigger than the stock
filter that comes with the kit. You can get them from CirKit in
England (thanks to everyone who told me about CirKit!) for maybe US$35
total. That's half the price I paid for my SuperKit but a decent IF
filter is what makes a CW rig usable to me (along with a bunch of
other RX features such a simple RX won't have, but for the price,

Good Luck

Geoff NQ7A Austin, TX

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