The Heathkit HW-101
by Greg Latta, AA8V

Main Page and Exterior Photos
of the Unrestored Transceiver

Front View - Unrestored
Click on the image for a super detailed view.

Heathkit HW-101 Pages:
 Heathkit HW-101 - Main Page and Exterior Photos of the Unrestored Transceiver  Alignment
 Interior Photos of the Restored Transceiver  Modifications
 Transceiver RestorationNew  Schematic Diagrams and Circuit Descriptions
 Power Supply RestorationNew  Manuals and Advertisements
 Power Supply Schematic Diagram and Circuit DescriptionsNew  
Links will become active as I make progress on the restoration.

Important Safety Note: Working on or testing equipment such as the HW-101 is extremely dangerous since very high voltages are present when the equipment is turned on, and may even be present when the equipment is turned off and unplugged. If at all possible, do all work with the equipment off and unplugged and be sure that the capacitors are properly discharged before working on the equipment. The operator assumes all risk and liability in such matters! Do not work on this type of equipment unless you are experienced with working around very high voltages!

Introduction and Historical Background:
Some years ago a friend of mine gave me an HW-101 destined for the trash bin. It did not include the power supply and had been cannibalized. It was not in a condition where it could be restored. However, it was still useful as a source of parts like the knobs, tubes, and variable capacitors. I carefully stored it away for future use.

Sometime in the last five years (2017-2022), a neighbor brought over another HW-101. He was not a ham, and just wanted to listen in with the HW-101. The HW-101 included the power supply, and did not appear to be modified or cannibalized in any way. It was, however, very dirty and not in a usable condition. It would have to be checked out/repaired before it could even be turned on. I offered the use of a spare Heathkit SB-104 I had on hand that he could use to listen in on. He left the HW-101 with me so I could check it out. I did not have time to immediately look at the HW-101 and carefully packed it away. Time passed and he moved away with the SB-104, leaving me with the HW-101. It thus turned out to be a trade, and a good one at that. I was thus in a position where I could now fully restore the HW-101, knowing that I now had two, one that could be used for parts if necessary.

It has been sitting patiently for a few years, waiting for restoration. I recently retired and finished up other big projects I was working on, and have decided to begin work on restoring the HW-101. Close inspection has revealed that the power supply contains several bad capacitors and resistors, and will need to be gutted and rebuilt from the ground up. The transceiver is complete and unmodified (except for the replacement of the output phono connector with an SO-239 connector), and it contains the optional CW crystal filter. I don't think I could ask for it to be in better condition!

This is a work in progress. The first thing I will do is rebuild the power supply from the ground up. As I make progress, these pages will be updated and more of the links will become active.
73,
Dr. Greg Latta AA8V

About The Heathkit HW-101:
The Heathkit HW-101 was one of the most ubiquitous transceivers ever made. It was sold from 1970 to 1983. The circuitry is nearly identical to the Heathkit SB-102, but at a substantial savings. Some 30,000 to 40,000 were reported sold, most assembled by hams at home. The transceiver operates on 80m, 40m, 20m, 15m, and all of 10m (without the need for extra crystals). It features a pair of 6146 finals run in class AB1 which provide an input of 180W PEP on SSB and 170W on CW. Output is 100W PEP on SSB and CW except on 10m, where it is 80W. The receiver is double conversion with separate crystal filters for SSB and CW (optional). The optional 400Hz CW filter can be switched from the front panel. A separately available power supply (HP-23 or HP-13) is needed to run the HW-101.

The tube lineup is as follows:
0A2 voltage regulator
6HS6 RF amplifier
6HS6 first receive mixer
6AU6 isolation amplifier
6AU6 1st IF amplifier
6AU6 2nd IF amplifier
6BN8 product detector and AVC
6AU6 VFO amplifier
6CB6 2nd transmitter mixer
6CL6 driver
6EA8 speech amplifier and cathode follower
6EA8 1st transmitter mixer
6EA8 2nd receive mixer and relay amplifier
6EA8 CW side-tone oscillator and amplifier
6GW8 audio amplifier and audio output
12AT7 heterodyne oscillator and cathode follower
12AT7 VOX amplifier and calibrator oscillator
12AU7 sideband oscillator
6146 final amplifier (2)

The diode lineup is as follows:
6 germanium diodes: balanced modulator, RF sampling, and crystal calibrator harmonic generator
9 silicon diodes: ALC rectifiers, anti-trip rectifiers, and DC blocking
1 zener diode: cathode bias

The transistor lineup is as follows:
MPF-105 FET-VFO
2N3393 voltage regulator

Exterior Photos of the Unrestored Transceiver:

Scroll Down or Select A Link Below:
 Front View Without Cabinet
 Rear View Without Cabinet
 Right Side View Without Cabinet
 Final Amplifier Cage
 Tube Testing
 Repair Label

These pictures were taken in March of 2022 when I began work on the HW-101 and its power supply.
It is in the condition that I received it, except that in a couple of the pictures the tubes have been cleaned.

 
Front View Without Cabinet:
This is a front view of the HW-101 with the top of the cabinet removed for inspection and tube testing. It is in quite good shape, compared to others I have seen. All of the knobs are present and the main tuning knob turns smoothly. The slide switches are stiff and appear to be stuck, and rather than force them at this point I will wait until later when I can lubricate and clean them. The front panel is remarkably clean compared to some that I have seen. There is no evidence of smoking haze.

 
Front View - Unrestored
Click on the image for a super detailed view.



 
Rear View Without Cabinet:
In this view from the rear the tubes have been cleaned and tested. All were found to be good. The circuit boards are relatively clean, and the only apparent modification is the replacement of the output phono connector with an SO-239 connector. All of the electrolytic capacitors appear to be original, and they will eventually be replaced. The rubber drive belts for the preselector control are very worn and cracked, but still intact. These will also need to be replaced. The serial number label is still present showing that the serial number is #10347

 
Rear View - Unrestored
Click on the image for a super detailed view.



 
Right Side View Without Cabinet:
In this side view the tubes have not yet been cleaned. The circuit boards are dirty, but not excessively so. Compared to some other HW-101s that I have seen, the circuit boards are "clean". The ceramic power resistors at front right are clean and in good shape. Large tan paper electrolytic capacitors can be seen at the left rear and right front. These appear to be original, and will need to be replaced. The fact that they are original indicates that it is unlikely that there has been a previous attempt to restore the unit.

The red label visible at front of the picture on the side panel is quite important and is discussed below.

 
Right Side - Unrestored
Click on the image for a super detailed view.



 
Final Amplifier Cage:
This is a picture of the interior of the RF output cage. The 6146 finals have been removed for cleaning and testing. There is little dirt inside the cage or on the tank coil. All of the solder joints look very good, and the parasitic suppressors are in good shape. There doesn't seem to be any evidence of overheating, indicating that the transceiver output was kept within it ratings.

 
Final Amplifier Unrestored
Click on the image for a super detailed view.



 
Tube Testing:
All of the tubes were tested on my Hickok 800A tube tester. This tester actually loads down the tube under test and measures its amplifying ability. All of the tubes tested fine except for the 6BN8, which was a little on the weak side but will probably work fine. The RCA 6146 finals tested fine, but the only real test for a final tube is to place it in actual service.

In this picture you can also see the top cover on the right. It is in good shape. It just needs a really thorough cleaning.

 
Tube Testing
Click on the image for a super detailed view.



 
Repair Label:
A red service label is attached to the right side panel. It indicates that the transceiver was serviced at Heathkit on February 6, 1974. This is incredibly important because of the following:

1. The label indicates that the transceiver was assembled before February 6, 1974. The assembly date of most HW-101s is impossible to determine. We now know that this unit was assembled in the early 1970s.

2. After servicing the transceiver, Heathkit would have done a full alignment and checkout before returning it to the customer. So, as of February 6, 1974, this particular transceiver was fully operational and up to specifications, without wiring errors and other possible problems, much like a factory wired unit.

Knowing the above facts definitely helps out in the restoration process because we now know that:

a. there are no wiring errors.
b. circuit changes made by Heathkit after February 6, 1974 are unlikely to have been done and will need to be performed.

 
Repair Label
Click on the image for a super detailed view.




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