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I have attached the Heathkit SB-102 Service Bulletins, down the list is
one about low grid drive problems.<br>
wd8aam<br>
van lincoln Minnesota<br><br>
====================================================================================================================<br>
At 10:17 12/24/2014, p.nettles wrote:<br>
<blockquote type=cite class=cite cite="">I have an SB-102 that exhibits
similar symptoms, but loses grid drive as it heats up. If I keep it
cool<br>
(even added a muffin fan) it delays the problem.<br>
Will be watching for an answer from one of th SB gurus......Glen are you
monitoring? <br>
Perry KF5SMU<br>
================================================================================<br>
-------- Original message --------<br>
From: Janusz Juryk <br>
Date:12/23/2014 15:23 (GMT-06:00) <br>
Subject: [Heath] Grid meter reading on SB-102 <br><br>
Good day,<br>
I'm in the midst of aligning my SB-102. the receiver portion went very
well ansd started on the transmitter part. <br>
All the readings associated with Plate ,HV, etc are right on except the
Grid which has no deflection what so ever.<br>
Any suggestions on where to look for the cause?<br>
Janusz ve2zhp<br>
_______________________________________________<br>
Heath@puck.nether.net<br>
<a href="https://puck.nether.net/mailman/listinfo/heath" eudora="autourl">
https://puck.nether.net/mailman/listinfo/heath</a></blockquote><br><br>
<h1><b>Heathkit Service Bulletins: SB-102 (Complete
1966-89)</b></h1><b>Joseph W Lutz</b>
<a href="mailto:heath%40puck.nether.net?Subject=Re%3A%20Heathkit%20Service%20Bulletins%3A%20SB-102%20%28Complete%201966-89%29&In-Reply-To=%3Cmailman.29139.1294703226.4768.heath%40puck.nether.net%3E">
joelutz at JUNO.COM </a><br>
<i>Fri Apr 3 16:37:36 EST 1998</i> <br>
<hr>
<br>
<pre>
November 25, 1970
SB-102
Bulletin No.
SSB
Transceiver
SB-102-1
Meter Zeroing
Original 10-147 control tolerance not sufficient to allow zeroing in all
units. This part is being respecified to a closer tolerance.
In the
meantime, any field problems requarding zeroing of the meter can be
corrected as follows:
Change: R-107 from 100K Ohm to 82K Ohm [PN 1-159].
--------------------------------------------------------------------------------------------------------------------
September 14, 1972
SB-102
Bulletin No.
SSB
Transceiver
SB-102-2
Repeated Heterdodyne Oscillator Tube
Failure
Change: R-212 from 220 Ohm to 330 Ohm 1/2 Watt resister [PN 1-4].
<font size=6>
--------------------------------------------------------------------------------------------------------------------
March 23, 1973
SB-102
Bulletin No.
SSB
Transceiver
SB-102-3
Low Grid Drive - Alignment Problems
This has been related to the differences [internal electrode
capacitance]
between Tung-Sol & RCA 6146's. Purchasing has ceased buying
Tung-Sol
tubes; all new stock since late 1972 will be RCA's which give better
performance. In addition, an additional alignment sequence is being
put
into the manuals which insures adequate grid drive -- previous tune-up
was done in receive only where the peaks were broader than required for
transmitter tuning. The new procedure uses the receiver sequence to
get
in the "ball park"; the added sequence peaks for maximum grid
drive.
The following modifications to the manual will help avoid the many
questions:
PAGE 103: 8th step, right column, last two sentances:
Then turn the meter switch to GRID [grid current]. The meter
should
have some up-scale indication. The meter may read as much as full
scale
-- this is normal.
PAGE 104: left column #2:
Turn the meter switch to GRID & adjust the MIC/CW LEVEL control for
a
grid current reading, just enough so a peak may be seen when making the
adjustment in the next step.
PAGE 104: Right Column #4 - will be deleted.
PAGE 119: Right Column #14 - will be deleted.
----------------------------------------------------------------------------------------------------------------
</b></font>
March 30, 1973
SB-102
Bulletin No:
SSB
Transceiver
SB-102-4
LMO Instability
We have a possible cure for some of the LMO instability problems in the
SB-102. The following should help eliminate any stress on the LMO
chassis when installed on the main chassis.
Remove and discard the lockwashers & nuts used to mount the LMO to
the
chassis.
Use instead a #6 flat washer [PN 253-25] & hex lock not [PN 252-27]
at
each lug, tightening each lug A TURN AT A TIME in a criss-cross pattern.
We recommend this be done on all SB-102 units in for service even if
customer has no complaints about LMO.
----------------------------------------------------------------------------------------------------------------
October 29,1973
SB-102
Bulletin No:
SSB
Transceiver
SB-102-5
Low 40 Meter Output
1. REMOVE the 1-1/2" bare wire from hole 1 on the DRIVER PLATE
circuit
board & the ground foil of the RF
DRIVER board.
2. Connect a 3/4" bare wire between the ground foils of these
same two
boards.
3. REMOVE the 1-3/4" bare wire from hole 1 in the DRIVE GRID
circuit
board & the ground foil of the RF
DRIVER board.
4. Connect a 3/4" bare wire between the ground foils of these
same two
boards.
5. Remove the 2-3/4" bare wire which ties the groundfoils of
the circuit
boards to the shields.
6. Remove the coil cover. Then REMOVE four of the light
spring clips &
their
hardware as shown:
[[[NOTE: the pictorial shows removal of the set of clips &
hardward
located directly down from the 2 holes in the cover; the other set to be
removed is directly across and down from the 3 holes in the cover.]]]
7. Readjust the driver grid & drive plate coils as instructed
on page
102 in the SB-102 manual.
------------------------------------------------------------------------------------------------------------------
May 23, 1974
SB-102
Bulletin No:
SSB
Transceiver
SB-102-6
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-102
Bulletin No:
SSB
Transceiver
SB-102-7
SB & HW Series Instability & 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.
-------------------------------------------------------------------------------------------------------------------
May 23, 1974
SB-102
Bulletin No:
SSB
Transceiver
SB-102-8
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.
<font size=6>
-----------------------------------------------------------------------------------------------------------------
December 18, 1974
SB-102
Bulletin No:
SSB
Transceiver
SB-102-9
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.
----------------------------------------------------------------------------------------------------------------
</b></font>
May 2, 1975
SB-102
Bulletin No:
SSB
Transceiver
SB-102-10
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 [PN 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.
--------------------------------------------------------------------------------------------------------------
June 5, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-14
Relays Remain Energized After Transmit Condition
After keying the transceiver with PTT for thirty to forty seconds, a
positive voltage in excess of 10 volts appears at the control grid, pin
9
of V12, thus keeping the relays energized.
To correct the problem, replace V12 [PN 411-124]. IEC brand tubes
have
been found defective in several cases, but other brands may also cause
this problem.
---------------------------------------------------------------------------------------------------------------
June 5, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-15
Poor AGC Action
Leakage in the 6HS6 tubes [PN 411-247] at V10 and/or V11 has been found
to cause:
- poor AGC action
- Fast S-meter decay
- poor sensitivity when RF
gain control is fully clockwise.
This usually occurs after warmup of at least an hour. A positive
voltage, usually over 1 volt, will appear at the grid, pin 1, of either
one or both tubes.
Replacement of the tube with the positive voltage corrects the problem.
----------------------------------------------------------------------------------------------------------------
June 5, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-16
100KHZ Calibrator Spurs
Strong signals may occur at other than 100khz points.
Look at the calibrator output [ahead of output diode] with an
oscilloscope. Use high input gain and a slow sweep speed. If
the upper
portion of the sine-wave signal appears choppy or uneven, the Y201
crystal may be at fault.
After installation of a new crystal [PN 404-43], recheck with
oscilloscope.
----------------------------------------------------------------------------------------------------------------
July 24, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-17
Poor Preselector Tracking
This problem is more noticeable on the 10-meter band. It may be
caused
by the drive belt slipping or by one of the variable capacitors not
turning due to excessive friction inits bearings.
Check the belt for being loose or worn and replace as needed.
Lubricate
the bearing of the variable capacitors.
If lubricating the capacitor bearings does not allow the rotor to turn
freely, replace the capacitor [PN 26-122].
------------------------------------------------------------------------------------------------------------------
July 24, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-18
Carrier Nulls with IC14 Trimmer Plates Completely
Meshed
If C14 nulls the carrier with its plates fully meshed toward V2 [to the
right], relocate C18, 12pf capacitor, to the other section of the null
trimmer [C14].
-----------------------------------------------------------------------------------------------------------------
August 7, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-19
Relays Chatter In VOX Mode
This may occur when the VOX gain is in the near-full CW position with
the
MIC level advanced past the 12 o'clock position. Also, the unit
will not
return to receive when the operator stops talking.
Check the tube at V1. A "GE" tube will tend to oscillate,
thus causing
the above problem. Other 6EA8 tube brands should operate properly
at V1.
----------------------------------------------------------------------------------------------------------------
August 7, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-20
Loading Capacitor Turns As Plate Capacitor Is Rotated
This problem can be caused by:
- Insuffiecent friction
in the loading capacitor or;
- Excessive friction
between the plate and load tuning shafts.
If the problem persists after freeing and lubricating the shafts,
install
a rubber grommet [PN 73-3] on the loading capacitor shaft between the
pulley and the RF cage. Apply slight pressure to the grommet as
the
pulley set-screw is tighted. This will add enough friction to keep
the
loading capacitor still while tuning the plate control. Use only
as
needed.
--------------------------------------------------------------------------------------------------------------
August 7, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-21
"Chirping" & Slow Receiver Recovery
If "chirping" of the audio in the receive mode and slow
recovery of the
receiver after long periods of transmitting are encountered, remove the
cover of RL2 and check for carbon buildup at the base, just below the
contact. Clean dirt or carbon tracks, or replace if necessary.
A dirt or carbon buildup will cause the +300 volts to be applied to
adjacent contacts such as the bias or AGC lines, adversely affecting
receiver cutoff by upsetting the operation of 1) V12, receiver mixer; 2)
V10, RF amplifier; and 3) V11, first receiver mixer.
--------------------------------------------------------------------------------------------------------------
August 22, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-22
S Meter Drift
If the S meter drops below zero and pins after 1/2 hour of operation,
there may be leakage in one or more of the following tubes: V3, V4, V10
or V11. New RCA tubes may exhibit the same problem. The
following
procedure will aid in finding the leaky tube:
1. Disconnect R415 to
isolate V3 and V4 from the AGC line.
Monitor the control grid at P1 of V3 for several minutes. If the
voltage
drifts in the positive [+] direction, V3 or V4 is leaky. Proceed to
step
2. If the voltage remains stable, go to step 5.
2. Remove the white/blue
wire from pin 2 of T102 and repeat the
test. This will isolate V4 from V3. If the voltage still
drifts, V3 is
at fault.
3. To verify, reconnect
the white/blue wire and then disconnect
R101. Monitor the voltage at pin 1 of V4. The voltage should
remain
stable.
4. Reconnect R415 and
R101.
5. Disconnect R408 and
check the voltage at pin 1 of V10. If
voltage drifts, replace V10. If the voltage is stable, replace
V11.
6. Reconnect R415 and
R408.
Straight substitution with new tubes may not work if more than one tube
is causing the problem, since even a small leakage can cause the drift.
When you replace a tube, check for stable voltage at its control grid.
Replace with the tube which gives most stable voltage.
------------------------------------------------------------------------------------------------------------
September 26, 1978
SB-102
Bulletin No:
SSB
Transceiver
SB-102-23
Poor IF Sensitivity
Check C101. It may have inadvertently been wired to point 2.
It should
be wired to point 15. It is an "easy-to-overlook" wiring
error that
would cause the transceiver to have low if sensitivity which would
result
in poor receiver sensitivity and low power output.
-------------------------------------------------------------------------------------------------------------------
April 25, 1979
SB-102
Bulletin No:
SSB
Transceiver
SB-102-24
Low Power Output; Poor VOX Sensitivity
It has been determined that Sylvania, RCA and Westinghouse brand tubes
do
not functionproperly at locations V3 and V4.
The brands found to work at other locations are: El-Menco, IEC,
General
Electric and Realistic.
Westinghouse tubes at other locations throughout the unit may cause low
power output and VOX problems. It is suggested not to use
Westinghouse
tubes at all.
----------------------------------------------------------------------------------------------------------------
September 20, 1979
SB-102
Bulletin No:
SSB
Tranceiver
SB-102-25
Low Transmitter output; Low
Receiver Sensitivity
When cleaning the unit during prework [tube sockets, potentiometers,
etc.], don't overlook the SSB/CW filter slide switch located with the RF
gain control. This switch handles both transmit and receive signals
and
dirt and grease build-up can affect the performance of both functions.
--------------------------------------------------------------------------------------------------------------------
January 21, 1980
SB-102
Bulletin No:
SSB
Tranceiver
SB-102-26
Low Grid Drive on Certain
Portions of One or More Bands
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
March 7, 1980
SB-102
Bulletin No:
SSB
Tranceiver
SB-102-27
Finals Will Not Neutralize;
C913 at Maximum Capacity
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
April 10, 1980
SB-102
Bulletin No:
SSB
Transceiver
SB-102-28
Germanium Diode Change
+ + + + Information not yet available + + + +
-------------------------------------------------------------------------------------------------------------------
November 13, 1981
SB-102
Bulletin No:
SSB
Transceiver
SB-102-29
Tone in Audio when Switched to CW;
Relay Chatters when Key is
Closed
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
September 21, 1984
SB-102
Bulletin No:
SSB
Transceiver
SB-102-30
S Meter Drifts; IF Oscillates
Check the brand of 6AU6 tubes at V3 and V4. If a brand other than
GE is
used at these locations, replae them with GE brand tubes. Parts
Replacement will stock only GE brand of 6AU6 tubes [PN 411-11].
------------------------------------------------------------------------------------------------------------------
That is all that I have on the SB-102 up to 1989. Enjoy!
73 de Joe W7LPF/4
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