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Woody's 
JOHNSON PACEMAKER TRANSMITTER
BE PATIENT, There's a lot of photos to download

WUI
at www.w0ui.com
  

Woody's
partial test bench - Summer, 2014

Left-to-Right Second Shelf 
Linksys 16-port network switch, MFJ-249 SWR/antenna analyzer, 
Heathkit HD-10, HD-1410 keyers, parts bin, 
small amplifier for testing work done on electric guitars

On right shelves: 
Yaesu YS-500 140-525 mHz SWR/Power meter, assorted 12vdc power supplies
Left-to-Right First Shelf 
Triplett Model 601 Type 2 VTVM, IFR FM/AM-1100s service monitor with spectrum analyzer, Tektronix 2246 100-mHz Oscilloscope
On desk:  Yaesu FT-401b HF transceiver 




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E. F. Johnson Model Number:  240-301   (2) SN 16518 (below)


E. F. Johnson Model Number:  240-301   (3) SN 16723  (below)


Over the years W0UI has owned three of these transmitters
(1) is gone
This page will deal with radios (2) and (3)

Radio (2) is original and has not been recapped or restored 
other than standard management of tube performance and replacements.
Radio (3) had apparently seen use in the US Citizen's Band (CB) service at some point as holes had been drilled in the front for two CB-related add-on buttons.
Due to their prominent location, I have chosen to not remove them at this time.

  CLICK HERE to email Woody

Built for perhaps four years: 1956, 1957, 1958 and 1959
Other Johnson transmitters of that era all required an external SSB Exciter 
but this rig was the first attempt by EF Johnson of a transmitter 
with the then-new sideband feature built-in.

Johnson Viking Pacemaker
Modes: SSB/AM/CW
Bands: 80 - 10 Meters
Input Power: 90W-SSB, 35W-AM, 90W-CW
Final Tube: A single 6146b
SSB Method: Phasing
New Price/Year: $495 wired 
(never offered as a kit)
Years of production:  1956-1959
Size: 11.5"h x 21.0"w x 16.5"d
Approx. Weight: 61 lbs

When plugged into an MFJ dry dummy load via 
a digital power meter using key-down CW:
80-meters measured 68-watts RF output and
10-meters measured 50-watts RF output

It has 17-tubes (AKA:  Valves)
6AU6 6BE6 6AU6 6CL6 6146 6AU6 
12BH7
ECC81 ECC81 12AX7 12AU7 12AT7 12AT7 
6AL5
6X4 
5U4G
5R4GY 
0A2
0B2 0B2

Johnson Pacemaker PDF Manual (18.5 MB)
Johnson Pacemaker PDF Schematic
(3 MB)
EF Johnson 1957 Color Sales Flyer 
(7.44 MB)

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UN-RESTORED PACEMAKER (2)
ABOVE CHASSIS



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UN-RESTORED PACEMAKER (2)
UNDER CHASSIS


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TRANSFORMERS

22.1211
138713
25919
P3027




A 120v auxilliary cooling fan added in years past by a former owner. Power is fed from Pins 6 and 7 off the nine-pin octal plug on the rear apron.

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RECAPPED PACEMAKER (3)
ABOVE CHASSIS

- This radio had apparently seen use in the US Citizen's Band (CB) service at some point as holes had been drilled in the front for two CB-related add-on buttons.
Due to their prominent location, I have chosen to not remove them at this time.


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RECAPPED PACEMAKER (3)
BELOW CHASSIS


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A COMMON PROBLEM (below)
IF you are experiencing blown 5-Amp fuses in the power plug
THEN read on:
Note here that the metal tube cover (left) has shifted to the right.


If it touches the variable capacitor (BALANCE CONTROL) and causes a short circuit 
it will cause Resistor R82 to burn open (it is the blue 1500-ohm resistor behind L8).

This, in turn, can cause one or both of the 5-Amp Fuses in the power plug to blow.
It impacts the low-voltage (350 volt) winding of the main power transformer (T2).
Note that, if T2 is burned 
(perhaps due to higher than 5-Amp, or Slow-Blow fuses being used in the plug rather than standard recommended Fast-Acting fuses)
then you are likely hosed as the transformers are no longer being made and, therefore, are not available anywhere.

Make sure that the tube shield is not allowed to brush up against the BALANCE capacitor.

 
Here we see the 1500-ohm R82 resistor after being replaced 
(standard Radio Shack 1500-ohm 1/2-watt) - below


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HIGH VOLTAGE INSULATION BREAKS DOWN
In my Pacemaker (1) I experienced problems with the insulation cracking from age allowing a voltage arc.
Once the problem was resolved, the radio again operated normally.
Unfortunately no photos of how I fixed it remain.



OTHER RELATED PACEMAKER WEB PAGES: 
A great resource: Emmitt's Fix It Shop 
Rig Reference

Radio Museum

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YouTube Camera Scan of a Johnson Viking Pacemaker Transmitter

YouTube Tune Up of a Johnson Viking Pacemaker Transmitter

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CLICK HERE to read a further technical analysis of the Pacemaker from AB2RA.

 

WARNING!! 
There are High Voltages with enough punch to easily kill you 
exposed all over inside these old rigs
both above and below the chassis.
The capacitors can hold a lethal charge 
well after voltage is turned off and the rig is unplugged. 
Make sure to bleed off capacitors with an insulated and grounded screw driver 
before touching anything 
even after the unit is physically unplugged from the AC outlet.

Remember the old ham radio and electronics practice... 
Work on the radio one handed leaving one hand behind your back.
If you have both hands inside the unit and accidentally touch a lead or brush a capacitor
current could potentially pass through your body and stop your heart.

Always instruct others to turn off the circuit breaker 
or unplug the radio 
before touching you if you are bit else they might be electrocuted, too.

Since 5 April, 2013:


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All personal materials, comments, pictures copyright 1997-2014 R  Linwood (4L RANCH)