			November 11, 1976
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-1

			    No VFO Output

Several L30 [PN 40-1859] coils have been found with the color dot on the
wrong lug.  The color dot should be on the coil center tap lug.  Q.A. is
checking all kits and parts stock.
--------------------------------------------------------------------------------------------------------------------
			November 11, 1976
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-2

			    No VFO Output

When mounting the VFO capacitor to the capacitor mounting bracket, 6-32 X
1/4 screws must be used.  If 6-32 X 3/8 screws are used they will short
out to the stator plates of the VFO capacitor.  A good indication that
this might be the case is a low voltage, below 1.5V, across ZD301.
--------------------------------------------------------------------------------------------------------------------
			November 18, 1976
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-3

		        Trimmer Capacitor [PN 31-76] NLA

When C139, C146 on the front end circuit board requires replacement, use 
[PN 31-85].
-------------------------------------------------------------------------------------------------------------------
			November 24, 1976
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-4

	     Audio Gain Decreases When Sharp Pulses Are Received

                           *******This Bulletin Superceded by
HR-1680-6*******
--------------------------------------------------------------------------------------------------------------------
			January 6, 1977
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-5

			    IF Oscillation

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			February 21, 1977
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-6

			    IF Oscillation

                                     *******Supercedes HR-1680-4*******

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			March 7, 1977
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-7
	      Fuse F201 Blows When Servicing Audio/Regulator
                                                        Circuit
Board		   

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			March 22, 1977
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-8

		        Receiver Front End Stability

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			May 13, 1977
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-9

		           Front End Oscillates

	                 *****Superceded by HR-1680-10*****

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			July 8, 1977
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-10

		           Front End Oscillates

	                   *****Supercedes  HR-1680-9*****

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			July 24, 1978
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-11

		               Preselector Drifts
			
The preselector may drift off resonance, usually about one minute after a
band change.  This is most noticeable on the 40 meter band.

To solve this problem install a 10 kilohm resistor [PN 6-103-12] in
parallel with C114 and C115.  This provides a DC return path for diodes
D105 through D108.

Make this change only when necessary.
----------------------------------------------------------------------------------------------------------------
			May 7, 1979
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-12

	    8.65 MHz Bandpass Filter Won't Adjust Properly
   	
Change the 10 pf cefamic capacitor at C143 to a 5-25 pf trimmer capacitor

[PN 31-85].  This component will fit directly.
-------------------------------------------------------------------------------------------------------------------
			July 30, 1979
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-13

	              No AGC When Case Bottom Installed

This may be caused by the left-front foot screw touching terminal strip
CK
(junction of R5 and R6).  To correct, bend terminal strip toward front of
unit.
--------------------------------------------------------------------------------------------------------------------
			February 8, 1980
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-14

                                    Sweep Aligning the 8.65 Bandpass
Filter

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			February 8, 1980
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-15

                                 S Meter Reads S9 or Pins for Most
Signals

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			October 21, 1980
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-16

                                 Audio Oscillations and Pilot Lamp Dims
When
                                                   Tuning a Strong
Station

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			November 25, 1980
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-17

	                              Tantalum Capacitor Change

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			August 28, 1981
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-18

	                                   R7 Control Change

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			August 28, 1981
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-19

	                               IC201 Regulator Change

+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
			October 25, 1982
HR-1680							Bulletin
No:
S/S Receiver						HR-1680-20

	       Schematic Correction - Diode Numbers D2 and D4
                                                             Interchanged
 
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
That's all that is shown for the HR-1680 (1966-89).  Hopefully one of
these days I will be able to talk those that have the years we are
missing to lend them to me so they can be posted for all to use.  Enjoy!


73 de Joe  W7LPF/4  [NNN0KUU]
QWCA - SOWP - NCVA - FISTS - RCC
Gordonsville, Va 22942 [Orange Co]



