HEATHKIT SERVICE BULLETINS (GH Series).
Joseph W Lutz
joelutz at JUNO.COM
Sun Jun 1 14:16:12 EDT 1997
Hi gang,
Rather than getting backed up in typing info that I have taken off
the fiche, I decided to go ahead and send some of what I have already
done - exclusive of the HW-8 info that I have already sent out. Hope it
is useful to some of you that are into Heath Green.
-------------------------------------------------------------------------------------------------------------------
July 10, 1968
Instability -- Trouble
shooting
Amateur Products
Bulletin No.
SB101, 100, HW100
GH-1
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.
--------------------------------------------------------------------------------------------------------------------
August 20,
1968
Audio Amplifier & VOX Circuit
Troubleshooting
Guide
Amateur Products
Bulletin No.
SB & HW Tube Type Transceivers
GH-2
It is assumed that the basic steps such as making DC voltage measurement,
checking tubes and 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
position.
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 set for .1V at 1KHZ
can be used as the signal source:
MIKE CONNECTOR LUG 1
.1 VAC
PIN 2 OF V1
.02 VAC
PIN 6 OF V1
10-15 VAC
LUG 4 LEVEL CONTROL
10-15 VAC
LUG 5 LEVEL CONTROL
.5 VAC
PIN 9 OF V1
.2 VAC
PIN 8 OF V1
.1-.3 VAC
CENTER ARM OF VOX SENSITIVITY CONTROL 5-15 VAC
PIN 7 OF V17
5-10 VAC
PIN 6 OF V17
40-50 VAC
JUNCTION OF C211-D201
40-50 VAC
PIN 9 OF V12
9-15 VAC
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 possible open or poorly grounded
shield.
- Check for continuity through each of the shielded cables.
- Check for a proper ground at the mike level control.
If the frequency response of the audio stage is not within specifications
check the value and 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
operational characteristics due to heat.
--------------------------------------------------------------------------------------------------------------------
July 7, 1969
Amateur Products Relay Chatter
Bulletin No.
SB-101, HW-100
GH-3
Prevention of relay chatter can be accomplished by bypassing RF to ground
in VOX circuit. This RF is picked up by mike cables, etc. Install a
.001mfd disc capacitor (Part No. 21-14) at hole 8 to adjancent ground
foil on bottom of the bandpass circuit board. This point has two
red-red-white wires connected to it also.
--------------------------------------------------------------------------------------------------------------------
Okay troops, thats it for now - back to work in the basement taping up
the drywall and trying to get it ready to move all the equipment in this
upstairs room to where I can start operating most of them. CIAO!
73 de JOE
- - - - - - - - - - -W7LPF/4 (NNN0KUU)- - - - - - - - - - - - - - -
QWCA - NCVA - SOWP - FISTS
Gordonsville, Va 22942 (Orange County)
Looking for: Heathkit HR/HX-20, MR/MT-1,
Collins 516F-2, 312B-4, EFJ TR Switch
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
More information about the Heath
mailing list