$45/1 space _S100/2 adjacent _$200/3 adjacent S_ $50.00 S_

* $15.00 at door 4 'S25.00 at door, if available t Admission ticket must be ordered with flea market spaces

* May 17, 18, 19, 1996 *

73 Review

Number 30 on your Feedback card by Dean Lewis WA3WGV

Number 41 on your Feedback card

Oak Hills OHR-400 4 Band QRP Kit

Ah! the joys of building!

Jeff M, Gold AC4HF 1751 Dry Creek Road Cookeville TN 38501

I had not built a kit in awhile and my personality had started to deteriorate proportionally. I seemed to have forgotten how therapeutic the building process is for me, I started to rationalize that \ have built one of everything and that placing components on a board was just not as much fun as it used to be. I couldn't resist the temptation when I heard about the Oak Hills fourbander. Four bands, three of my favorite (20. 30, 40 meters) and one that 1 need to spend some more time on (80 meters) anyway. So I toid the XYL 1 needed some money for counseling, and sent off for the kit.

1 anxiously awaited the arrival of Ihc kit. My children are now pretty well grown up. no grandchildren in the near future, so I guess this is the closest I can conic for the time being to an anxiously awaited arrival. I got home from work on Friday afternoon. This was a real big weekend tor me. Three days off and the weather was supposed to be nice for the first time in eight weeks. What more could I ask for? \ came home from work and there the box from UPS that I had been waiting for. Having significant I > matured (if you can belie\e this one), I went and changed out of my work clothes before taking the prize lo my workshop to unpack.

The first thing 1 noticed when opening the box was how carefully and professionally it was packed. All of the little components were packed inside the case and sealed so that you don't accidentally throw them away. There arc three printed circuit boards, not counting the optional keyer. The boards are the absolute best I have ever come across (I have seen some as good, but none better). They are solder masked and have a terrific si Ik-screening. There is no question which parts go where. The receiver board has the parts fairly wrell packed, so the very high quality silk-screening is a definite plus.

Another thing I have noted is that Dick from Oak Hills really listens to his customers. This is evident with the docu mentation. The doc umentation comes in several sections which are individually stapled. The printing is top quality and eas\ for even my old eyes to read without the need for those new reading glasses (so in essence the kit makes me feel a iiule younger). The first section of the documentation is the Assembly Instructions. Oak Hills has a couple of pages on things you need to be aware of to make your building experience more pleasant and more likely to have you succeed with ihe project. The instructions are step by step, but not in the hand-holding "put this part R3 in hole in section 1A" way Heath used to do it. I really appreciate the clearness of instructions and not having to read and reread something many times to figure out if what I read and thought I understood is what the writer meant for me to understand.

Working with technical writing in the computer field. 1 realize how nard it is to write good instructions. Oak Hills also has started to include ver> professional diagrams for the final assembly in with the documentation. There are separate sections for cach board thai list all the components, a schematic, and an excellent, enlarged overlay. One of my main criteria for pleasure in building a kit is knowing what the author really means when building instructions are given. I feel it takes some of ihe therapeutic value away from the project when there is ambiguity in any of the steps.

The parts for each board come separately wrapped. This is another example of Oak Hills' listening to the customers.

From OHR-400
thick OHR-400

For each board the parts are separated by *>pe. such as resistors and capacitors I usually hate the first stage of building, which involves the sorting out of the parts and checking to make sure that ihey arc all there. It used to take a great deal of time to separate and label the pails. Now 1 use little plastic parts bins and dump ihe resistors in one, the capacitors in another, and so on. I find it fairly easy to then use my magnifying glass (even Oak Hills couldn't solve ihis problem for me} to make sure I gel the right part when I start stuffing the board.

I find that after a few minutes of separating out the parts and documentation 1 can get into the project fairly quickly.

The cahinet for the kit is also very high quality and has a great paint job. The panels are beautiful 1\ screened, i believe them to be as good in quality as the major transceiver manufacturers' cabinets.

There arc two distinct and equally important aspects of a kit for me: how much fun it is to build and how much I like lo operate it when it is done. I have found that there are sufficient variables involved in implementing a kil design so thai even the best designs may not work as they should when they are built. Some rigs arc jusi more fun to operate than others, I finally took some time recently to ponder ihis aspect of my bit tiding experiences. I have built about every kit on the market in the last three years, I can pinpoint exactly what constitutes a pleasurable building experience for me. The pans in the kit have to he high quality;

Ohr 400 Qrp

Photo A. The OHR-400 QRP kit is sensibly packaged and logically arranged. 42 73 Amateur Radio Today * January 1996

the documentation has to he clear tested and revised to eliminate errors, with no ambiguity al all: the printed circuit board needs to be high quality and clearly screened; and there should be separate pans lists by circuit board, with a clear enlarged parts overlay.

The fun-to-operate part is much more nebulous. This aspect is very personal, I have come up with a scieniitie method to determine this aspect. It is really quite easy 1 have many rigs on my workbench. [he number and type seem to change constantly. 1 find there are some rigs that I just keep using after ihe initial testing and evaluating. The reason for this is that they seem to me to work better and are more fun to operate. I put my Norcal 40 in this category, as well as the Oak Hills kits 1 have built. I think it is pretty amazing that small companies like Wilderness Radio and Oak Hills can put out such high-quality kits. They work very well as long as they are assembled properly.

Building i found no unwanted surprises while building the kit. 1 built up the three boards and put in the optional iambic keyen All went together quickly, even though 1 checked my work very carefully to make sure the correct pans were in the proper places on the printed circuit board and also checked all of my soldering joints with a magnifying glass.

It can lake quite a few hours to tracc problems such as diodes or electrolytic capacitors being put in the wrong direction. or having the wrong values of resistors or capacitors placed on the board. It is much more economical and pleasurable to take a few extra seconds for each part and verify that they do indeed belong at a particular location. The board was a pleasure to solder. The plated through-holes are very easy to solder and make lor strong connections. These also complicate unsoldering, so make sure you have the right parts in the right holes! If you should make a mistake (most of us do), I recommend a good quality solder sucker (can be purchased ai Radio Shack) and with this board some solder wick is helpful.

Testing and Alignment

It was another Friday evening and the end of a really tough week. 1 am supposed to take my wife out for dinner, and my son is already at a friend s house for the weekend. Sounds like a good lime for a romantic weekend...well, there was one problem. I was super-stressed from (he week's events. I was in dire need of a "therapy session."

I did my mandatory chores, changed to my +tplay clothes" and went into the shack. I went to the bench and checked the Oak Hills Research 400 thai I have put hundreds of parts into and over 50 wire connections and mounted many

Photo A. The OHR-400 QRP kit is sensibly packaged and logically arranged. 42 73 Amateur Radio Today * January 1996

mechanical connectors, switches, and!


The project passed the initial smoke test. I was very relieved when nothing sizzled on power up. I then took out the alignment procedures and was ready to roll, If you don't have the proper equipment or can't get it aligned. Oak Hills will align the completed rig for $65, including shipping it back to you.

The initial frequency setup went \ery quickly. Three of the four ba; ds came up exactly on frequency with no adjustments necessary. Getting the fourth on frequency was a matter of adjusting a trim capacitor. It was very easy, using a frequency counter as is suggested, I switched back and forth between the bands and the oscillator for each band started with no problems. The only time-consuming adjustment involves adjusting a coil and a trim capacitor to get the correct bandw idth out of the YFO. I also like to get it so the dial reads near the real frequency, I didn't encounter any difficulties with this parL

You next adjust two coils on the oscillator board for each band for peak signal voltage as measured on a scope, 1 later found thai i did not tune the 20 meter band coils correctly I noticed this when I tested out the rig and found the SWR was high on 20 meters, even though I knew I w as using a resonant antenna. There were two peaks for the coils, using a scope to monitor. You need to check to make sure you peak them on the correct frequency, as stated in the manual. On 20 meters I noticed that when I was peaking on ihe wrong frequency the power output went up to about if) walls on my QRP wattmeter. but was right in range at tiie designated frequency.

Your next step is to move to the receiver board and adjust (he voltage ai a given point using a trimpot. That is all you do on that board at this time.

Moving on to the TX/REC board, you tune a set of coils for cach band to get maximum signal output as measured on a QRP wattmeter. The two coils interact so that you need to go back and forth a few times, 1 noticed that 20 meters wasn't pulling out a full 4-5 watts, I found that 1 had the power supply turned back to about 9 volts. I turned the supply-up to 13 volts and the pow er came right up. All the bands tuned up easily and 1 got the correct power output on each band.


* 4-full duplex radio porii

* Optional Autopaidi available

* Unique C W for each port

* DTMFcontrol from any port ■ 100 user command macros

* 300-9600 baud setiai port

* 4-Layer boar J construction

* Priced for any groups hud gel

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