I sat there looking at the new NW30 kit from Roy at Emtech, including a
beatiful case and his audio filter. Could I really build this thing? Let's
see...what did I have to work with....
1.-An old Millen GDO.
2.-An NC38S xcvr
3.-An analog VOM
4.-My trusty Weller WP-40 soldering iron (plugged into a Dremel speed
controller).
5.-Radio Shack solder sucker and various sizes of solder wick
6.-A 30 meter resonant dipole mounted in the rain gutter.
7.-St.Louis tuner
8.-An old Triplett 200uA meter.
My first challenge was winding the vfo toroid. Winding 48 turns of #34 wire
on a T37-7 core is indeed a challenge. Roy tells me that he is changing
this to a larger core and larger wire. Anyhow, halfway thru winding, I
broke the wire. An e-mail to Roy and he had some wire to me the next day.
This kit can be built in stages, checking each stage before going on to the
next. Not having a frequency counter, I went out of sequence and finished
the vfo and the receiver sections. Roy has a built-in tester of sorts which
really came in very handy. It allows you to connect a sensitive meter and
check out the various stages as you go along (I used the 200uA meter for
this). I checked for shorts and did some resistance measurements with the
VOM. Everything seemed OK...so I connected the antenna, 12 volts and a
small speaker and turned the juice on. No smoke. Signals started popping in
before I tweaked the tuned circuits (I used the meter for this). The
receiver is really hot.
I finished the rest of the kit and everything seemed to check OK, so I
mounted it in the case. This is when I had a few problems....I was getting
some spurious oscillations on receive which seemed to emanate from the
MC1350 IF amplifier. Hmmm...it wasn't doing this when it wasn't in the
case. Ground loop???? or ????. Took it out of the case, and sat there
looking and thinking. Hmmm...the case is also painted on the inside. I'm
not getting good ground connections....so I removed the paint from the case
where all the jacks, pots ,etc. are connected....reassembled the unit and
voila!!!! everything was fine. I used Roy's excellent intructions and the
handy built-in tester to tweak the xmit section. Not having a frequency
counter, I did have a little trouble setting the xmit frequency on the
proper sideband. So I finished the audio filter and using that with the
38S, got it close enough. Listened around and heard a W7 calling CQ. Called
and he came right back with a 559. He assisted me by using his receiver and
I further tweaked the xmit freq control and got the offset right on.
I should do a separate report on the audio filter, but for now I can say
that it really pulls sigs out of the mud and works with other xcvrs too.
I'm thinking of one for the 38S.
There are a few suggestions or changes that I made. I threw away the
tin-plated IC sockets and used Augat machined gold plated pin sockets. I
also did not use the wire dial pointer. BTW....not having a watt-meter
(see, I told you, I didn't have an electronics laboratory), I used the 38S
to listen to the quality of the xmit signal....and I backed off on the
power output control 'til it sounded clean in the 38S and then asked during
other QSO's for critical reports.
This is a real fun rig to build, and I would highly recommend it to anyone
who has limited test equipment. Of course, those items would really help.
BTW, the usual disclaimers, I have no connection with EMTECH - just a very
satisfied customer.
I've used a lot of bandwidth here, but if anyone would like further info,
please e-mail and I will respond directly.
Al - AA6SO
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