(in manuscript at head of page: Ed)
STEPHEN JAMES (? :Ed) POLAR ELECTRONIC DEVELOPMENTS, ROMVILLE ROAD, LIVERPOOL


EDL144G OPERATING INSTRUCTIONS

PACKING
The inside of the unit is transit packed to protect the P.A. valve.
This packing must be removed before switching on.

TO DO THIS PROCEED AS FOLLOWS:-
1. Remove 4 screws from top half of cabinet using a POZI-DRIVE screw driver.
2. Slacken 2 screws on one side of bottom of cabinet.
3. Remove lid and internal packing.
4. Replace lid and tighten all screws.

General

This linear amplifier for 144MHz employs a rugged push-pull tetrode operating in
AB2 for the linear amplification of transmitters in the 10-20 watt range.

A single stage dual gate mos-fet pre-amplifier is also fitted to enhance the 
performance on receive. This has variable gain, which is accomplished by varying 
the potential on gate 2. This produces a gain of approximately 20db in the 
maximum gain setting. Under strong adjacent channel signal conditions it may be 
necessary to reduce the gain to prevent cross-modulation effects in the 
associated receiver.

R.F. input and Antenna connectors are the familiar S0-239 and are mounted on the
rear panel and clearly marked. Also mounted on the rear panel are the bias 
control potentiometer and the mains fuse.
 
R.F. VOX CIRCUIT
The switch from receive to transmit is accomplished by a sophisticated and 
sensitive R.F. vox circuit, which senses an incoming signal and operates the two 
change over relays. 

A delay of approximately 1 second is built in to eliminate dropout during pauses 
in speech.

Setting up for S.S.B. Operation.
1. Connect suitable antenna to Linear Antenna Socket.
2. Connect transceiver to R.F. Input Socket.
3. Connect 3 core mains lead to suitable A.C. outlet. NOTE: Earth lead (coloured
Green/Yellow) must be connected to mains earth conductor.
4. Switch on power switch, indicator should light. Set meter switch to P.A. 
current.
5. Allow 1 minute for valve to warm up.
6. Turn R.F. gain control to maximum and tune in a signal on the transceiver.
Adjustment of control will vary sensitivity of pre-amp.
7. Set microphone gain on transceiver to minimum and operate push to talk. Linear

										cont………



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should switch from receive to transmit mode. (If desired, connecting the P.T.T.
Socket on the rear of linear to transceiver P.T.T. rail will override R.F. Vox).
8. With FM/SSB Switch set to SSB. Press "Set Idle" switch and adjust bias 
control to set P.A. standing current to 4OmA on meter.
9. Insert reduced carrier and peak GRID Tune Control for a maximum reading.
10. Switch to R.F. output and adjust P.A. Tune and P.A. Load for maximum.
11. Insert full carrier and repeak all 3 control for maximum indicated R.F. 
output. 
12. Switch transceiver to S.S.B. and meter to read P.A. current. Linear is ready
for operation.


NOTE
The tuning should be done as quickly as possible with pauses to allow P.A. valve
to cool. Lengthy tune-ups off resonance can cause permanent damage to the P.A.
valve.


C.W & F.M. OPERATION

F.M.
1. Set up as for S.S.B. (40 mA Standing Current in S.S.B. position)
2. Switch to F.M. position.
3. Adjust P.A. Tune and P.A. Load. For maximum out put.

NOTE
P.A. Current is internally limited to approx. 150mA in F.M. Mode.
DO NOT OPERATE FOR LONG PERIODS UNLESS OPTIONAL COOLING FAN IS FITTED

C.W.

1. Set up as for. S.5.B. 
2. Set P.A. Standing Current to zero with no drive
3. Adjust P.A. Tune and P.A. Load for maximum out put.
4. On C.W. P.A. Current can be driven to 3O0mA driving Keying. (200 Watts in put).

General Points
1. DO NOT USE MORE OUTPUT POWER THAN NECESSARY (Reduce drive).
2. DO NOT OPERATE LINEAR INTO HIGH V.S.W.R. LOAD. This will considerably
shorten the life of the P.A. valve.
3. DO NOT OPERATE WITHOUT A LOAD CONNECTED. This will cause destruction of the 
P.A. valve.
4. DO NOT OBSTRUCT THE COOLING VENTS WITH MAGAZINES, LOG-BOOKS ETC, ON TOP OF 
THE CABINET

CONT....

(there is no 
continuation: 
Ed)