(click image to enlarge)


by William Eric McFadden


From the HW-16 manual:

The Heathkit Model HW-16 CW Transceiver is a high performance and economical amateur radio receiver and transmitter. Although it is designed with the Novice Class operator in mind, this Transceiver is also an excellent piece of equipment for the General Class operator. The Transceiver provides full break-in CW communications in the lower 250 kHz segments of the 80-, 40-, and 15-meter bands.
The transmitter is crystal-controlled, using 80-meter crystals on 80- or 40-meter bands, and 40-meter crystals on 40- or 15-meter bands. The Transceiver also has provisions for an external VFO.
Input power to the final stage is adjustable for 50 to 90 watts input. A 75 watt marker on the meter, which indicates plate current, represents maximum power for Novice Class operation. All three stages of the transmitter are grid-block keyed. The only tuning required when changing bands or frequency is adjusting the final Tune capacitor.
The receiver uses dual conversion for excellent image rejection and the receiver's front end is crystal controlled for excellent stability. For high selectivity, the receiver uses a 500 Hz crystal filter. The receiver is automatically muted each time the key is depressed, providing full break-in operation. No external antenna relay is required, as antenna switching is accomplished within the Transceiver.
HW-16 Specifications:


 Transmitter



RF Power Input 50 to 90 watts (adjustable)
Frequency Control 80-meter crystal or VFO on 80-meter band.
80- or 40-meter crystal, or VFO on 40-meter band.
40-meter crystal or VFO on 15-meter band.
Keying Grid-block, break-in, with automatic antenna switching and receiver muting.
Output Impedence 50 ohm unbalanced, SWR not to exceed 2:1.
Side Tone neon relaxation oscillator.

 Receiver



Sensitivity Less than 1 microvolt for 10 dB signal-plus-noise to noise ratio.
Selectivity 500 Hz at 60dB down.
Image Rejection 70 dB or better.
IF Rejection 35 dB or better.


Intermediate Frequency 3396 kHz.
Antenna Impedence 50 ohm unbalanced.
External Speaker Impedence 8 ohm.

 General



Frequency Coverage 3.5 to 3.75 MHz.
7.0 to 7.25 MHz.
21.0 to 21.25 MHz.
Power 120 VAC 50/60 Hz.
Transmitter Tube Complement 6CL6 Crystal Oscillator.
6CL6 Driver.
6GE5 Final.
Receiver Tube Complement 6EW6 RF Amplifier.
6EA8 Heterodyne mixer-oscillator.
6EA8 VFO mixer-oscillator.
6EW6 IF amplifier.
12AX7 Product detector-oscillator.
6HF8 1st audio and audio output.
Transistor Complement 2N1274 muting circuit.
Dimensions 13-3/4" wide x 11-1/2" deep x 6-1/2" high.
Net Weight 20 lbs.

Description of HG-10 from Heathkit catalog:

The new Heathkit HG-10 VFO covers from 80 through 2 meters with each band separately calibrated on a rotating drum-type slide-rule dial. The circuit uses the popular series-tuned Clapp oscillator with a cathode-follower output for isloation and regulated plate voltage for maximum stability. Its vernier tuning has a 20 to 1 gear drive... and there's a "spot" switch for off-the-air-tuning.
The circuit is designed for grid-block keying with the new Heathkit DX-60 or for cathode keying with other transmitters. Everything is mounted on a rigid steel chassis for superior mechanical strength and freedom from chassis instability... and it's all wrapped up in a handsome cabinet to match the DX-60. Power is obtained from the transmitter... just plug it into the DX-60, or make simple changes to use with other transmitters. All cables are supplied.
HG-10 Specifications:


 Band Coverage:
 80, 40, 20, 15, 10, 6 and 2 meters.

 Load Impedence: 50K ohms or more.

 Output voltage: 5 volts R.M.S. or more, with no load.

 Output connections: phono plug.

 Front panel controls: Function Switch (Stby/Opr/Spot), VFO tuning & Band selector.

 Tube complement: 6CH8-oscillator-cathode follower; OB2-voltage regulator.

 Power requirements: 1. from Accessory socket of DX-60, using cable furnished,
2. from accessory socket of DX-40, with simple changes,
3. From other sources: 140 volts min. @ 25 ma; 6.3 volts ac or dc at 0.75 amp.

 Cabinet size: 9-3/8" wide, 9" deep, 6-1/2" high.

I earned my Novice license just after the FCC allowed Novices to use VFO-controlled transmitters but for as long as I can remember I have wanted an HW-16 for my station. I finally purchased an HW-16 and HG-10B VFO in February, 2008. Both were cosmetically clean but the HW-16 lacked a sidetone on transmit and received signals were unstable and somewhat raspy, and the HG-10B lacked a power-cable.

1969 Heath catalog page -- click to enlarge In rennovating the HW-16, I installed a set of replacement electrolytic capacitors (from Hayseed Hamfest), replaced the sidetone-circuit neon lamp, and performed a realignment. The receiver instability remained, however. I thought I had traced this to a mechanically-unstable trimmer capacitor on the main tuning capacitor. I have been able to shim this trimmer-cap with fiber washers, and plan to replace trimmer-cap with a more mechanically-stable piston-type trimmer eventually, but even with the trimmer tightened all way down the receiver instability is still very evident on strong signals. Liberal application of De-Oxit and reflowing solder joints on the circuit-board haven't the problem so more work is required before this transceiver will be enjoyable to use. (Here are notes from WB4LNM, "One of the Hams from Heath" regarding this instability problem.)

UPDATE: After noticing that the HW-16 CW filter response seemed much too wide, I used Spectrogram to look at the filter response and the results pretty plainly indicate that my HW-16 effectively has no functional CW filter. This might help explain the warbly, harsh receive audio my HW-16 has. Presented below are two Spectrogram plots. The first is of the HW-16. The second is of my Elecraft K2 with the 700Hz CW filter engaged.

Spectrogram plot of HW-16 -- click to enlarge Spectrogram plot of Elecraft K2 700Hz filter -- click to enlarge

I have received glowing reports on the quality of the HW-16's transmitted signal.

In building the required power and rf-signal cables to connect the HG-10B to the HW-16, I found that the VFO had been modified by a previous owner for use with a DX-40 transmitter. Fortunately, the mods were simple to undo and are well documented in the HG-10B manual. With the required cables built, the VFO worked beautifully and didn't even require alignment.

I acquired a second HW-16 in September, 2009. It is costmetically ugly, lacking a dial, dial-glazing, bezel, and cabinet-top, but seller assured me that the rig operated well. The asking price was such that I could justify the purchase based on the value of the tubes alone. This rig is serving as a parts-donor rig for my other HW-16.

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Attributions:

1961 catalog page found at Technology Systems.
1963 catalog page found at Technology Systems.
1969 catalog page found at HW16-Heathkit-HW-16 at Yahoo! Groups.