Note
HW-18-1 CAP 1968-1972 $119.95
HW-18-2 MARS 1968-1969 $109.95
HW-18-3 160 m 1968-1969 $109.95
The HW-18 series of transceivers borrow heavily from the single-bander radios (HW-12A, et al) released two years earlier. The 18 series was released in March 1968 for use with the Military Affiliate Radio Service (MARS), the Civil Air Patrol (CAP), and on 160-meters.
The 160-meter version covers 1800 to 2000 kHz. The CAP and MARS units are virtually identical rigs covering 4450 to 4650 kHz. In fact, the CAP and MARS units were so similar that Heath packaged the CAP version with the MARS assembly manual—along with a small booklet of changes needed to turn it into the CAP assembly manual.
The HW-18 series is a 12-tube design built on a single large circuit board. The units run about 200 watts SSB input employing crystal filter sideband generation, or about 40 watts in the “carrier” mode, which provides a low level carrier with the sideband. Note that these rigs are intended primarily for SSB operation. Carrier (AM) operation is not recommended for more than 30 seconds at a time.
The CAP unit came standard with a crystal for USB operation. The MARS unit could be USB or LSB depending on the crystal specified by the user, 3396.500 kHz for USB or 3393.500 kHz for LSB. The 160-meter unit came from the box as LSB.
All three can operate on one of two switch selectable crystal frequencies—transmit and receive frequencies are locked together. Receiver sensitivity is 0.5 µV. Selectivity is 2.1 kHz at 6 dB down.
CAP and MARS units usqe crystal frequencies between 7863 and 8023 kHz. The 160-unit uses crystals between 5200 and 5400 kHz.
The crystal sockets (Y6 and Y7) are located on the chassis just behind the front panel, between the speaker and the S-meter. Socket Y6 is closest to the front panel and is selected with the front panel switch in the right-hand position. Trimmers are located adjacent to each socket.
Features of the HW-18 series include fixed tuned operation, an illuminated S-meter, and a built-in speaker. The transceivers were supplied with a hard-wired Turner 350C ceramic microphone.
While the HW-18 series is based on the single-banders, there are four differences worth noting: the HW-18 series does not use a VFO, does not have VOX capability or selectable sidebands, and uses electronic T/R switching.
Front panel controls include on/off/volume, clarifier (adjusts receiver frequency plus or minus), reception (“local” or “distant”), mode (SSB or “carrier”), meter function, and channel selector. There are front panel screw driver adjustments for S-meter zero and bias setting. A rear panel control adjusts mic gain. The microphone is hard-wired to the unit through the middle of the front panel.
The rear panel contains a mic gain control, an RCA connector for a 50Ω antenna, an 11-pin power plug (for use with the HP-13 or HP-23 series power supplies), and a ground post.
The units require only a VTVM and a dummy load for alignment. Caution: Run only at 250 VDC B+. Two-tone green wrinkle finish matches other HW series radios. The front panel of all three versions is labeled only “HW-18,” so the easiest way to tell them apart is to look at the blue and white series plate—usually found on the rear apron—which will include the dash 1, 2, or 3.
The clever person should be able to put a CAP or MARS unit on 75 meters without too much trouble. To the best of my knowledge such a modification has never been described in any of the popular magazines, though a mod for 60 meters was described in Electric Radio.
The CAP version is seen most often. The 160-meter version is genuinely rare.
There is no built-in power supply. The HP-23 and HP-13 series power supplies are recommended.
Power supply plug pin-outs:
Pin 1: –130 VDC
Pin 2: filament common
Pin 3: +250 VDC
Pin 4: +800 VDC
Pin 5: nc
Pin 6: 12 VAC filament
Pin 7: ground
Pin 8: nc
Pin 9: switch
Pin 10: switch
Pin 11: nc
CRYSTAL FREQUENCY CALCULATION
HW-18-3: operating frequency = crystal frequency – 3393.500 kHz.
FOR USE WITH A VFO
While Heath made no provision for it, VFO operation is possible by connecting the VFO output directly to one of the crystal sockets (observe polarity) via a short length of RG-58U. VFO output should be between 1 and 2 volts RMS. The cable should be routed along he chassis and should be kept as far away from tubes V3, V4 and V9 as possible. The 160 meter version can be used with an LMO from an SB-100, 101 or 102, or even the SB-640 remote LMO, since these tune in the correct frequency range (5200–5400 kHz). The 73 Amateur Radio review mentions this possibility. See references below for additional information.
References:
Review. CQ. Dec 1968, p. 24.
Review. 73 Amateur Radio. Mar 1969, p. 50.
Adding a VFO. 73 Amateur Radio. Jul 1969, p. 100.
Use on 60 meters. Electric Radio. Nov 2012.
Receiver Section
Frequency coverage:
HW-18-1: 4450 to 4650 kHz (crystal range 7863 to 8023 kHz)
HW-18-2: 4450 to 4650 kHz (crystal range 7863 to 8023 kHz)
HW-18-3: 1800 to 2000 kHz (crystal range 5200 to 5400 kHz)
Channels: 2
Clarifier range:
HW-18-1 and -2: ±100 Hz
HW-18-3: ±250 Hz
Sensitivity: better than 0.5 µV for 10 db signal-plus-noise to noise
Selectivity: 2.1 kHz @ 6 db down. 6 kHz @ 50 db down
IF: 3395 kHz
Image rejection: 80 db
IF rejection: 50 db
Input impedance: 50Ω, unbalanced
Audio response: 400 to 3000 Hz
Audio output power: 1 watt
Internal speaker: 8Ω, 4 x 6 inches
Transmitter Section
Frequency coverage:
HW-18-1: 4450 to 4650 kHz
HW-18-2: 4450 to 4650 kHz
HW-18-3: 1800 to 2000 kHz
Channels: 2
Transmitting modes: USB or LSB, depending on installed crystal; and low level carrier with sideband.
Frequency accuracy: 0.005%
RF input power:
SSB mode: 200 watts PEP
Carrier mode: 40 watts, minimum
Unwanted sideband suppression: 45 db minimum below peak output
Carrier suppression: 45 db minimum below peak output
Output impedance: 50Ω, unbalanced
Transmitter audio response: 400 to 3100 Hz
Microphone: high impedance, ceramic
Operating temperature range: +10F to +110F
Power requirements:
12.6 volts AC or DC @ 3.75 amps
800 VDC @ 250 mA maximum
250 VDC @ 100 mA maximum (caution: run only at 250 VDC)
–130 VDC @ 5 mA
Tubes: (3) 6EA8, (4) 6AU6, (1) 12AT7, (1) 12BY7, (1) 6EB8, (2) 6GE5
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
