Heath HW-99 Novice CW Transceiver
By Curt Holsopple, K9CH and Edith Holsopple, N1CZC
About a year ago, the Heath Company introduced a new rig that is truly elegant in its simplicity. The HW-99 CW transceiver is a thoroughly modern HF, CW-only radio that owes much to the lessons learned in developing the HW-9 QRP transceiver. This is not a warmed-over HW-16 from the 1960s. The Heath HW-99 is VFO controlled, tuning the bottom 250 kHz of the 80, 40, 15 and 10-meter bands (sorry, no 20-meter coverage!). It seems to be targeted primarily for Novice and Technician class operators using CW on the four HF Novice bands, but it should appeal to veteran brass pounders who think 50-W output is enough to work the world.
Like any good CW rig, no matter how simple or complex, the HW-99 has a sensitive and stable receiver, a solid and comfortable tuning dial with no apparent backlash, a tuning rate that is neither too slow nor too fast, a mellow-sounding sidetone and a well-keyed waveform. We have one major complaint about the documentation on the HW-99: We looked through the ½-inch-thick manual several times and never did find a block diagram of the circuit. Reading the more-detailed schematic diagram is no problem for the experienced person, but the block diagram is crucial for the beginner to get a handle on how the circuits interact.
Both the transmitter and receiver feature broadband circuitry so that no user-actuated preselector or final tuning are required during normal operation. This makes the rig simple to use--a nice feature for Novices. A transmitter using a solid-state output stage, however, requires a low SWR for proper operation. Therefore, the industry trend to broadband rigs brings with it the requirement for antenna matching networks and SWR meters, and thereby adds costs and complexity to setting up a beginner's Amateur Radio station. An ALC circuit in the HW-99, however, does provide protection to the transmitter power amplifier if the antenna SWR is too high.
The HW-99 may look simple on the outside, but some very sophisticated circuitry lies within the dark-brown case. A separate low-pass filter is included for each band in both receive and transmit modes, providing optimum rejection of received spurious signals and transmitted harmonics. The receiver features a doubly balanced ring mixer, for a cleaner mixer-stage output. This results in fewer spurious responses (known as "birdies," those mysterious carrierlike signals that sometimes appear here and there on the band). The receiver's IF strip does an excellent job of rejecting signals on one side of zero beat, but isn't particularly sharp otherwise. We have no problem receiving and understanding Canadian USB phone stations operating on the low end of 40 meters. Even in weak-signal situations, we rarely have to run the volume control more than two-thirds of the way up before the speaker is overdriven! This rig has plenty of gain.
Heath claims that the HW-99 can be used in the full-break-in mode up to 30 WPM. Our experience indicates this may be the upper limit. There is a noticeable audio thump in switching from transmit to receive, but even when using earphones it is not objectionable. A relay disconnects the antenna from the receiver and solid-state switching handles all other functions when the key is closed. An internal variable resistor sets the time delay for return to the receive mode.
Building the Kit
Since Heath plugs the HW-99 as a Novice rig, we gave it the acid test--we let a relative newcomer to Amateur Radio build it. Edie, N1CZC, has been licensed less than three years, although she already holds an Advanced class license. Her busy life-style prevents her from spending much time inside ham gear, however. She was the perfect candidate to see if the HW-99 is truly a kit for the Novice builder.
Heath's reputation for high-quality instructions continues in the thick manual that comes with the HW-99. Heath's packaging of components is better than ever, which really helps inexperienced builders succeed. There is always that necessary step of getting the parts out and arranging them in some orderly fashion. Do not skip this step! The HW-99 kit has a lot of parts, and the time and care of checking through the parts list will be of great help later during the assembly process.
Since the HW-99 is a new product, and ours was shipped during the first two months of production, we were not too surprised at a fairly extensive list of corrections and modifications to the manual. It is important to incorporate this information into the manual carefully before assembly begins.
The HW-99 circuitry is fairly sophisticated, and the kit takes a long time for the beginner to build, but the inside of the radio is spacious enough for inexperienced hands to have little trouble during the construction phase. See Fig 1. Even if you're a veteran tinkerer, don't expect to grab this kit from the mail on Friday afternoon and have it on the air by Sunday evening. Edie spent 30 hours unpacking and building about two-thirds of the kit before she ran out of time--I needed another 20 hours to finish the job.
Alignment was relatively easy, although for accurate dial calibration a 10-Mhz frequency source is required. The instructions caution the builder not to push down on the slugs while adjusting the coils. They're not kidding! The slugs are quite delicate, and I managed to crack two of them; be very gentle.
Take special care when assembling the large tuning capacitor for the VFO. When you put the shield around the capacitor, be sure the metal can does not short circuit the wire coming out of the capacitor housing. Another problem: When shipped, the band-switch wafers were rotated 180° from their proper orientation. Once the band-switch wafers were reoriented, however, the receiver sprang to life, and we could proceed with alignment. The errata sheet from Heath corrects this problem on the drawing, but makes no mention of the correction in the step-by-step instructions.
After the power-supply subassembly was wired, we did the chassis subassembly tests prescribed in the book. The fuse blew immediately upon applying line voltage. It turned out that instead of the 2.2-megohm resistor that goes from the power-supply line cord to ground, a 220-ohm unit had been supplied on the component part strip. Of course, 220 ohms to ground on the line cord will cause the fuse to blow. We installed the correct resistor, and the power-supply checkout continued with no apparent problems. We then proceeded to install the large oscillator board. We still don't know why, but a filter capacitor in the power supply began to smoke and finally went SNAP! That power-supply breakdown caused the 12-V regulator to fail--in addition, an IC and a transistor were lost on the oscillator board. All components were easily replaced after a quick trip to Radio Shack. The power-supply problems did not return with the new components, although some additional ICs failed over time, probably from the stress of the initial problem.
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