HEATHKIT SERVICE BULLETINS - CONT.
Joseph W Lutz
joelutz at JUNO.COM
Tue Jun 24 21:45:07 EDT 1997
CONTINUING:
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JUNE 5, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-24
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.
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JUNE 5, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-25
100 KHZ 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.
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AUGUST 3, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-26
RECEIVER RECOVERY SLOW
THIS BULLETIN OBSOLETE. REFER TO BULLETIN NO: HW-101-36 DTD OCTOBER 10,
1978.
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JULY 24, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-27
ERRATIC VFO TUNING
Erratic tuning can be caused by an intermittant electrical contact in the
vernier drive of the tuning capacitor. This causes a change in the
ground path from the capacitor frame. This affects the capacitance and
subsequently, the tuning.
To prevent this, solder a heavy gauge wire or braid from the stop stud to
a solder lug under the closest mounting screw. This provides a suitable
short ground path from the capacitor frame to ground.
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JULY 24,1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-28
CARRIER NULLS WITH IC14 TRIMMER PLATES COMPLETELY
MESHED
SEE BULLETIN NO: HW-100-14 DATED JULY 24, 1978.
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JULY 24, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-29
POOR PRESELECTOR TRACKING
SEE BULLETIN NO: HW-100-13 DATED JULY 24, 1978.
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AUGUST 1, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-30
LOADING CAPACITOR TURNS AS PLATE CAPACITOR
IS ROTATED
SEE BULLETIN NO: HW-100-16 DATED AUGUST 3, 1978.
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AUGUST 3, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-31
RELAYS CHATTER IN VOX MODE
SEE BULLETIN NO: HW-100-15 DATED AUGUST 3, 1978.
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AUGUST 3, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-32
"CHIRPING" AND 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
21, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-33
ALC METER READS BELOW ZERO
SEE BULLETIN NO: HW-100-18 DATED AUGUST 21, 1978.
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AUGUST 22, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-34
S METER DRIFT
SEE BULLETIN NO: HW-100-17 DATED AUGUST 22, 1978.
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SEPTEMBER 26, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-35
POOR IF SENSITIVITY
SEE BULLETIN NO: HW-100-19 DATED SEPTEMBER 26, 1978.
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OCTOBER 10, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-36
RECEIVER RECOVERY SLOW
SEE BULLETIN NO: HW-100-20 DATED OCTOBER 10, 1978.
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OCTOBER 11, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-37
R-940 SHORTING TO SHIELD
To prevent the leads of R-940 shorting to ground, install a length of
sleeving [PN 346-1] on each lead of R-940.
This will be incorporated in future production.
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OCTOBER 13, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-38
POOR CARRIER SUPPRESSION
The HW-101 carrier suppression specification is -45db or below. If the
carrier cannot be nulled on both USB and LSB to this level, try changing
R9 on the modulator board from a 1K Ohm to a 390 Ohm [PN 1-48].
This change will reduce the injection level to the balanced modulator and
hence reduce the carrier suppression level.
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NOVEMBER 20, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-39
IDENTIFICTION OF THE 6146A TUBES
The 6146A tubes [PN 411-75] used at V8 and V9 of this unit are marked
'6146A' in white ink on the side of the tube. These tubes may also have
'6146B' etched in the galss. These tubes have been reworked by G.E. and
are acceptable for use in the HW-101. Most tube cartons will contain the
following insert to explain the situation to the customer:
IMPORTANT INFORMATION;
THE TUBE SUPPLIED WITH THIS NOTICE IS TYPE 6146A, AS PRINTED ON ONE SIDE
OF THE TUBE, EVEN THOUGH THERE MAY BE A 6146B ETCHED ELSEWHERE ON THE
TUBE ENVELOPE.
ALWAYS REPLACE V8 AND V9 WITH 6146A TYPE TUBES
Replace the backing from this label and place the label at any convenient
location inside the cabinet top.
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NOVEMBER 28, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-40
NOISE OR STATIC FROM SPEAKER WHEN CHASSIS TAPPED
LIGHTLY
If noise or static is heard from the speaker when the chassis is lightly
tapped, check for intermittent tubes, cold solder connections, or
intermittently shorting filaments in the pilot lamps by tapping each lamp
lightly. This produces noise in the filament supply but usually will not
produce any difference in the lamp brilliance.
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DECEMBER 11, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-41
RELAY CHATTER IN ANY SETTING OF THE VOX SENSITIVITY
CONTROL
If the relays chatter in the VOX mode, try performing the procedures in
BULLETIN'S HW-101-13, -31 and -38. If these changes do not correct the
problem, perform the following:
1. With a scope, check for excessive noise at the junction
[point 8] of R213 and R214. Any noise on the white-red-red wires coming
from the mode and function switches will override the reverse bias to
D201, thus activating V12B.
2. Replace the two white-red-red wires with shielded cable [PN
343-15].
3. Ground the shields to a ground foil near the junction of R213
and R214.
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DECEMBER 27, 1978
HW-101 BULLETIN NO:
SSB TRANSCEIVER HW-101-42
UNIT "WARBLES" WHEN CHASSIS IS TAPPED
This "warble" has been traced to the VFO assembly. This occurs
especially when the leads of the C946 and C953 capacitor combination is
too long, enabling the capacitors to vibrate.
To solve this problem, clue the top of C946 [4700pf] to the chassis wall
of the VFO assembly. The PN 350-12 glue may be used.
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Okay gang, thats all I have on my fiche for the HW-101. Enjoy! More
follows/Ciao!
73 de JOE
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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
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