October 3, 1968
HW-17							Bulletin No.
2 Meter Transceiver					HW-17-1

	   An Alternate Method for Adjusting Coil L-15 in the T-R 
		    Switching Circuit is as follows:

	1.  Tune up transmitter for maximum output per manual
instructions, [approximately 20 volts R.F. across a 50 ohm resistive
load].

	2.  Put R.F. probe at "ANT" terminal of the receiver circuit
board, [100 pf disc capacitor should be connected to terminal at this
time].

	3.  Key microphone and tune L-15 for minimum R.F. indication,
[R.F. voltage will normally be between 2.5 and 3.5 volts but in no case
should it exceed 4.0 volts].

NOTE:  In some cases it has been necessary to change C-128 from a 15 pf
to an 18 pf capacitor to reach a null point with coil L-15.
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			December 17, 1968
HW-17							Bulletin No:
2 Meter Transceiver					HW-17-2

		Audio, Transmit, Meter Sensitivity, Spot
			      Signal Mods.

Transmit-Receiver Audio circuits.

	1.  Change C233 from 10 uf to 50 uf. [Emitter circuit of Q11].
	2.  Ground the Emitter of Q12 to nearest circuit board Ground
Foil.
	     [These changes were made to increase thepercentage of
Modulation,
     	       improve Low Frequency Response, and stabilize any
tendency 	       toward instability].
	3.  Change R225 from 3.3 k-ohm to 1 k-ohm [Emitter circuit of
Q8].
	4.  Change R245 from 47 ohm to [1] k-ohm [Emitter circuit of
Q13].
	     ///NOTE: Fiche shows change to ' k k-ohm'///
	5.  Add an insulated Jumper Wire from CY1 to CF2 terminal strips.
                        [Optional].
NOTE:  The Bias Control must also be set properly as per manual
instructions, or the Red Lead may be disconnected from ground lug CG and
a Milliammeter inserted in series from Red Lead to CG and Bias Control
adjusted to a reading of 80 ma.
(These changes were made to reduce the residual hum).

Transmit Circuit

	1.  Remove ALL BUT 3-1/2 TURNS from coil L9 (Plate Circuit of
V1B).
	     (This change is made to change the resonance from 48 to 72
mc).
NOTE:  We do not have a 72 mc coil in strock at this time, BUT if you
have sent in your Registration card this part will automatically be
forwarded to you as soon as possible.

Optional Changes

	1.  To increase Meter Sensitivity on Receiver, reduce the value
of R307 	      and readjust METER ZERO control. (With a jumper
wire across R307
	      the meter will read full scale at approximately 25 uv input
at the
	      Antenna).
	2.  To reduce "SPOT SIGNAL" signal injection: unsolder the lead
of R107 
	      and lift from the circuit board, Solder Island A, on
transmitter circuit
	      board.  Solder one end of an insulated hook-up wire to the
exposed 
	      lead of R107 and connect the other end of this wire to the
solder pin
	      at Solder Island U, to which the VIOLET wire is connected. 
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			July 21, 1969
HW-17A							Bulletin
No:
2 Meter Transceiver					HW-17-3

		            Heath VFO Operation

Diode originally called for in HW-17A Manual (page 81) to be installed in
HG-10 VFO Oscillator cathode keying circuit should not be used as this
causes erratic or complete loss of oscillator output.  Green lead in VFO
should be connected to Lug 3 of terminal strip A.
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			August 25, 1969
HW-17							Bulletin No:
2 Meter Transeiver						HW-17-4

			  VFO Operation
 	
Some interaction has occurred when the HG-10 VFO is used with the HW-17
Transceiver.  With the present system, there is considerable RF loss in
the VFO.  This is caused by having the VFO switched effectively through
three diodes in series, which lowers the DC voltage in the cathode
circuits of the VFO.

To cure this, leave the VFO modifications as per the HW-17 manual stand
as is.  On the VFO PLUG, remove the wire going to pin 8 and reconnect to
pin 7.  In the HW-17, connect and solder a wire from pin 7 of SOCKET CT
to point D on the Receiver circuit board.  This HW-17 change should be
picked up in the manual at next printing.

The modified circuit will now bypass the T-R switch circuit.  The only
way to SPOT with the VFO is with the VFO Function switch.

Since the ration of HW-17 sold to those used with the HG-10 is so small,
it is felt that a manual insert is not required.
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