Oak Hills Spirit Review


From: Jeff M. Gold (JMG@tntech.edu)
Date: Mon May 31 1993 - 10:37:17 EDT

Here is my review (totally non-technical) of the
Oak Hills Research Spirit:

Single Band kit for 80, 40,30,20,or 15
Curtis Chip keyer (8044ABM)
Superhet receiver with diode ring mixer and RF pre-amp
4 pole crystal ladder filter followed by an on board audio filter
Switchable HP AGC circuit with manual gain control
2 watts audio output
VFO with 8:1 vernier drive
Sinewave sidetone oscillator w/frequency and level controls
5 Watts output
4"X6 1/4"X6 7/8" weighs 47 oz.
100% complete kit with pre-wound coils, PC boards are quality
double-sided and plated through and screened.

OK, that is what it says in the catalogue. I opened the box and checked
things out. There is a stack of stapled sheets that are the
instructions. There are large part overlays, a chart showing you how
to read the resistor codes, a detailed and well thought out parts list.
and the schematics.

This kit isn't the Heath step by step approach. The first page tells you
some general things about assembling the kit and soldering and be
careful type comments. The first step is to find all the parts and make
sure they have been sent to you. Next you find the Receiver board and
then it tells you to put in all the resistors followed by the
capacitors. The next steps do go through what you need to do. As the
process itself would get more unclear the directions get clearer.

After building a number of kits I find I like this approach best. I
first check off all the parts and label them on a piece of paper and
stick the wires through. This gives me a chance to make sure all the
parts have been included, familiarizes me with the parts and gives me a
double check about putting the correct parts in the right holes on the
board. I check them once while I am going through the parts check off
and then again before I place them on the board. I also find that
checking off the parts is my least favorite part, and when I do it this
way, when I start to build I don't have to go hunting for parts. Since
I have started to use this approach, my projects seem to work correctly
the first time (except for putting in an audio chip backwards and
smoking it.. well no one is perfect and I was able to get a replacement
for $2.00 at Radio Shack). I found the way the parts were listed on
the instructions made it very easy to identify them and check them off.
I found almost all steps in the final construction to be very clear and
unambiguous. I do a lot of documentation at my job. I find that most
instruction sets have places where the author meant one thing and the
words indicate something else.

OK, now for the kit. I think there were over 170 resistors in this kit.
It took me quite some time and energy to sort out the parts. I found ALL
the parts to be of top quality. The enclosure is excellent. I didn't see
any hint of cutting corners in any piece that was included with the kit.
After building kits from about all kit manufacturers, the quality of the
parts in this were the best. I have found that Ramsey uses some quality
parts and some real garbage..I think Ramsey's enclosures are real

The board was the single item that impressed me the most. Like it says
it is high quality plated through. You heat the joint and the board
sucks up the solder. The result is that you will be proud to show either
side of this board to anyone.. my wife comments on how her needlework is
beautiful on the front side, but she won't show the back to anyone, well
many of my projects are like that. With this one, I felt like displaying
the board in an art show.. what a proud pop I am. The silk screening on
the receiver board was ok, but certainly not great.. I found I put one
piece in the wrong place because I couldn't read the part #. Well this
really isn't a problem, and it was my fault. There is a clear large part
overlay that makes it a breeze to build.

The receiver board is jam packed with parts.. but the back of the board
is layed out so that if you use a fine tipped soldering iron you really
shouldn't have any problems with solder bridges. The transmitter board
was a lot less dense.

The Keyer board isn't plated through and not near in quality to the
other 2 boards.. be careful with this one.. I found it not nearly as
much fun to solder to as the other boards.

Once I got the parts checked off and labeled, I found it very easy to
assemble. The first part of the instructions that tell you to put on
about 200 parts are a mere 2-3 steps. Then when you put in the rest of
the parts the instructions (like assembling the chassis, the final
wiring and alignment) are detailed and clear. There are no checks as to
whether you have built it right.. like Heath's resistance checks, when
you are done, you power up and pray.

I was real careful with this kit, but got a little too excited at the
final assembly and had put one teeny weeny audio chip in backwards.. boy
did I feel dumb.. and when I powered up.. the smoke came out.. it failed
the smoke test (or is it it passed the smoke test, but failed to work).
It was very easy to spot the mistake, and since the chip was on a
socket, it was a breeze to correct. I checked the resistors and other
parts that fed it, and no problem at all.

The final alignment suggests a frequency counter. I can't ever get the
frequency counter in my MFJ antenna analyzer to read such low levels, so
I use my 757GX as my alignment tool. You just need to set a coil and a
capacitor to set the full 100kc bandwidth for the VFO. I take a piece of
copper wire, stick it in the antenna jack of my 757 and hold the loose
end over the oscillator circuit. It works just fine. The rest of the
alignment had some aspects I have never encountered before. You tune the
pitch of your TX out signal and the sidetone pitch (I once again used
the 757, put both rigs on dummy load, transmitted and set the Spirit for
the same note as the 757. I figured the Yaesu people knew what they were
doing and had the proper equipment when they did it). The TX alignment I
used my Oak Hills QRP wattmeter and you simply adjust a variable
resistor for power level and then 2 coils for maximum output. I spoke
with Dick at Oak Hills who suggest you tune it for the full 5 watts out
to get the best quality TX signal. Over the weekend I took the case off
a few times and tweeked various things. A note about the keyer weighting
adjustment. I started at the suggested middle position. The keyer was
acting really funky... couldn't really set it right. I turned the
weighting adjustment and it is now perfect..one of the better keyers I
have used..guess that is why a lot of people use Curtis chips. One of
the adjustments that you peak .. be careful that you are on the right
sideband.. I didn't have much audio level to my speaker, when I went and
re-read the instructions, it had cautioned me about it.. went back and
re-adjusted and everything was fine.

Ok, now for the real stuff.... how did it work. Well let me tell you
that the weekend of the CQ WPX CW contest is quite some time to test out
a new QRP rig. The rig puts out a full 5 watts (I turned mine back from
a little over 6 watts.. may have to have a friend put the oscilloscope
on it to check the signal out). The keyer works real smooth.. full break
in.. but has a minor little click in it.. don't think the click is going
over the air.. I have listened on another receiver. The receiver at
first deceived me and I will need to do some more testing. The bands
were really crowded in my QTH. The big guns were using big ammo. The rig
doesn't have a narrow and wide CW filter switch. This worried me.
During contests it is real nice to have a narrow filter available. I
tuned around and noticed that when the receiver got a signal, you really
only heard that one signal. At first I thought that this was caused by
the receiver being too insensitive. After spending the entire weekend of
the contest testing the rig out, I found that if I could hear them on
the other rig, I could hear them on the Spirit without other station
interference. I am not as of yet a person who possesses enough
electronics knowledge to go in and analyze the circuit and do
comparisons. I can do extensive "real-life" tests.. which from my
experience sometimes had more truth than theory.

I worked over 125 stations with my 5 watts and Gap vertical during the
contest. I worked to Russian stations, a S50S I think it was, an
Italian, a French, Alaska, a bunch of islands, and from the West Coast
to the East Coast and some other places in between. After I got the hang
of it, I got many returns on my first call.. not bad for 5 watts and a
vertical.. used the built in keyer, not my contest keyer and my Bencher

Other impressions: I would have left out the AGC on and off, the RF
control and made the keyer an option. I use a straight key most of the
time. The rig is BIG and HEAVY. A little smaller than my HW9, but not
much smaller. The chassis is solid... lots of metal. I think Oak Hills
can keep the best parts of this kit, get rid of the extras, and maybe
add a narrow filter and a S meter. I think they are coming out with
something like this in the near future. For a station QRP rig, it would
be pretty hard to beat this though.. and for portable operation it would
also be excellent, a little too big for backpacking.

Jeff, AC4HF

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