Heath Company HW-100 Schematic
May 23, 1974
SB-100 Bulletin No:
SSB Transceiver SB-100-1
Diode Leakage In The SB-100, SB-101, HW-100
The silicon diodes used in the SB100 & SB101 are standard power diodes rated at 500PIV & 750MA. For
each condition described, the diodes should be replaced with an equal value to maintain proper opration.
1. Diodes D902 & D903, when leaky, will have an effect on ALC indication. The ALC indication will be
normal for the first half hour to an hour. Then the meter indication will start dropping off until there is
very little indication.
2. D101, when leaky or defective, will cause slow or no receiver recovery after transmitting for any period
of time.
3. D905, under leaky conditions, will cause very slow or no receiver recovery and false meter indications.
The meter will kick up scale & slowly drift down to zero.
4. D201 will result in a decrease in VOX sensitivity to the point where the VOX circuit will not be
activated. It can also result in increasing VOX delay, causing the relay to stay in the transmit condition.
------------------------------------------------------------------------------------------------------------------ May 23, 1974
SB-100 Bulletin No:
SSB Transceiver SB-100-2
Alternate Method of Neutralizing the Final Amplifiers
NOTE: Be sure unit is off and power supply high voltage capacitors are discharged.
1. Disconect final plates & screen grid.***
2. Turn unit on.
3. Rotate the BAND switch to 28.5.
4. Place the VTVM RF probe in the ANTENNA connector.**
5. Set the FUNCTION switch to TUNE.
6. Rotate the LEVEL control fully clockwise.
7. Adjust the PRESELECTOR control for a maximum reading on the VTVM.
8. Adjust the FINAL control for a maximum indication on the VTVM, with the LOAD control set at the
50 ohm position.
9. Using an insulated screwdriver, adjust neutralizing capacitor for a MINIMUM indication on the
VTVM.
10. Readjust the neutralizing capacitor for a minimum indication on the VTVM.
11. Turn the FUNCTION switch to the off position.
12. Discharge high voltage power supply capacitors.
13. Reconnect final plates & screen grid.
**VTVM & RF probe will be needed.
***To remove screen voltage in SB-100, SB-101, HW-100 & HW-101 disconnect R920 (100 ohm
resistor) from buss wire between pins of V8 & V9. In the SB-102 removal of accessory plug is all that's
required. To remove high voltage in SB-100, SB-101 & SB-102 disconnect red wire at lug 4 (in Sb-100
lug 3) of terminal strip BK that goes to grommet BL. In HW100 & HW101 disconnect red wire going to
lug 1 of RF choke in final cage.
NOTE: Take adequate steps to eliminate any possible contact with B+ or B+ shorts to chassis after
disconnecting wire & resistor.
------------------------------------------------------------------------------------------------------------------- May 23, 1974
SB-100 Bulletin No:
SSB Transceiver SB-100-3
SB & HW Series Audio Preamplifier & VOX
Circuit Trouble Shooting Guide
It is assumed that the basic steps such as making DC voltage measurement, checking tubes & reviewing the
soldering have been completed.
The following information was compiled from the above transceivers in the 80M LSB position. The mike
level control was at the 9:00 o'clock poisition.
AC signal voltages are listed below. These voltages were measured from the microphone connector
through the VOX circuit. All measurements were made with a VTVM. A microphone or audio generator
for .1V @ 1KHZ can be used as the signal source.
Mike Connector Lug 1 .1VAC
Pin 2 of V1 .02VAC
Pin 6 of V1 10-15VAC
Pin 6 Level Control 10-15VAC
Pin 5 Level Control .5VAC
Pin 9 of V1 .2VAC
Pin 8 of V1 .1 - .3VAC
Center Arm of VOX Sensitivity Control 5-15VAC
Pin 7 of V17 5-10VAC
Pin 6 of V17 40-50VAC
Junction of C211-D201 40-50VAC
Pin 9 of V12 9-15VAC
By tracing the AC signal from stage to stage the point of trouble can be isolated & steps taken to correct it.
POSSIBLE TROUBLE AREAS
- Check each of the shielded cables for a possible open or poorly grounded shield.
- Check for continuity through each of the shielded cables.
- Check for a proper ground at the mike control level.
- If the frequency response of the audio stage is not within specifications check the values & installation of
C1, C2, C3 & C9.
- A change in VOX delay after operating for a period of time can be caused by leakage in diode D201.
The other possibility is a change in value of capacitor C213. Either component could experience a
change in operation characteristics due to heat.
---------------------------------------------------------------------------------------------------------------- May 23, 1974
SB-100 Bulletin No:
SSB Transceiver SB-100-4
SB & HW Series Instability and Corrective
Information
We suggest you check for each of the following possible causes:
1. Intermittent, rosin or cold solder joints.
2. Loose hardware at the tube sockets, terminal strips, circuit boards, shields and rear panel sockets.
3. Poor lead dress at tube sockets V8 & V9. The component leads must be short as possible.
4. Check C925 (Final tune capacitor) to be sure it is isolated from the tuning shaft. This is to prevent RF
from traveling on the shaft to the front panel.
5. Check all edges of the final enclosures for proper grounding to the main chassis.
6. Check the hardware for the side rails to be sure a good ground is being provided.
7. Be sure that all the ground clips on the coil cover are making good contact with the switch shields.
8. Check the soldering of the switch shields to the center pins of tube sockets V6, V7, V10 & V11.
9. Check the ground leads from the switch board & shields, to be sure they are going to ground foil & not
to the preselector capacitor foil pods on the RF driver board.
10. Check for broken or shorted pigtails on each of the shielded cables in the unit.
11. Check RFC801 & L901 for any signs of deterioration or physical damage, (burn spots). If apparent
replace the part.
12. Improper adjustment of the Het. Osc. coils could cause improper mixing action, resulting in the final
operating at a different frequency appearing as instability.
13. Change driver & final tubes then reneutralize per manual instructions.
14. Check driver tube shield to be sure that it has a good ground contact with the socket spring clip.
15. Check for a good ground between the front panel & chassis.
16. Check the SWR of the antenna system at the frequency of opertion. Should be below 2:1.
17. Check the antenna coax for leakage, poor connectors & broken shield connections.
18. Is the transmitter properly grounded?
19. Be sure all shields & tube shields are installed.
20. Realign using a properly terminated 50 ohm non-reactive dummy load. NOTE: This does not
include a light bulb.
21. Check for normal Het. Osc. test-point voltage.
22. Check for proper LMO injection voltage 1.0-1.5 VRF.
23. Check for a high AC ripple content in the LV-B+, HV-B+ and bias voltages from the power supply.
24. Check to be sure that the shafts do not touch each other in the insulated coupling, and that the set
screws do not touch the PA shield.
25. Check to be sure that the PA tune shaft turns the variable capacitor & is not slipping in the insulated
coupling.
-------------------------------------------------------------------------------------------------------------------December 18, 1974
SB-100 Bulletin No:
SSB Transceiver SB-100-5
Oscillations or Low Drive
Loose boards cause sporatic self oscillations & unstable RF conditions, particularly at the high [15 & 10
meter] bands. The comb brackets which ahve been used are aluminum & could not be soldered. Steel
brackets are now available [PN 204-2096] & should be used whenever encountered in the field. Both the
switch shields & the driver boards should be soldered to these brackets.
This change helps to increase grid drive as well as increase stability.
------------------------------------------------------------------------------------------------------------------
May 2, 1975
SB-100 Bulletin No:
SSB Transceiver SB-100-6
Self Oscillations Occurring After Installation
of Steel Comb Brackets.
It has been found that in a number of units, self oscillations are still occurring after installation of both steel
comb brackets [Part No: 204-2096]. To correct the condition, the screws around the RF driver board must
be tightened securely. Also, the lockwashers between the circuit board & chassis must be installed,
otherwise a good ground is not assured. Retightening screws which are already snug will also cause these
oscillations to disappear in units where it is a problem.
------------------------------------------------------------------------------------------------------------------March 26, 1976
SB-100 Bulletin No:
SSB Transceiver SB-100-7
S-Meter Drift
To bring the meter drift to an acceptable level, install the following:
CHANGE: R107 from 100K Ohm 1/2 Watt to 100K 1 Watt
[PN 1-28-1]
This makes the voltage divider string more stable with temperature changes caused by internal heating.
This change will be made in future production runs.
---------------------------------------------------------------------------------------------------------------September 27, 1977
SB-100 Bulletin No:
SSB Transceiver SB-100-8
Transmitter Oscillates in Transmit with the Mic Keyed
+ + + + Information not yet available + + + +
----------------------------------------------------------------------------------------------------------------February 22, 1978
SB-100 Bulletin No:
SSB Transceiver SB-100-09
Tuning Erratic
Some of the earlier LMOS can be opened up for service, such as cleaning the wiper contacts on the tuning
cap when tuning becomes erratic. Some of these units have fiber washers between the frame of the tuning
capacitor and the worm gear assembly. Intermittant contact between the teeth of the gears can change the
ground path for the tuning cap and also cause erratic tuning. Simply replacing a fiber washer with a metal
washer will give good connection between the tuning cap frame and the worm gear assembly to eliminate
this problem.
-----------------------------------------------------------------------------------------------------------------June 5, 1978
SB-100 Bulletin No:
SSB Transceiver SB-100-10
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