PN1-A and PN1-B Transmitter/Receiver

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Type: Portable Transmitter-Receiver
Variants: From nameplate data, the PN1 comes in  -A and -B versions. The A model was a manpack version with a telescopic antenna while the B model was  the fixed station version. PN-1B has no telescopic antenna but has a built in speaker.
Frequency Range: 3000 to 6000 KHz.
Frequency control : 3 crystal controlled frequencies
Sample frequencies actually used: 3480, 3600, 4172 and 4850 KHz
Transmitter Power Output:  2.5 watts
Tube Lineup: 2 x 1P5, 1A7, 1G4, 1H5, 1Q5, 1J6, 1H4, 1J6 and 1F5
Vintage: Believed to be 1940
Marconi type no: 118-980
Diagram: 141-206 (also see #99380 on the chassis of the PN1-A)

Dimensions: 15 1/2 " tall      15 1/2" wide           9 1/4" deep
Weight: 11.15 KG (24.6 lbs)  with phones, mike but without battery.
Telescoping antenna: 14 inches collapsed. 72 inches extended.
Power: Light duty 'B' battery 180 VDC and 3 volt 'A' battery - 6 to 8 hours
             Heavy duty 'B' battery 180 VDC and 3 volt 'A' battery - 60 to 80 hours.
             If the 'A' battery drops below 2 volts or the 'B' below 120 volts,
             then a battery replacement is required.
             Also requires a 3 volt 'C' battery.
Comment: One of two sirviving examples of a PN1A serial 189) is now located at 25 Canadian Forces Supply Depot in Montreal
 

 

EXTERIOR VIEWSA PN1A/PN1B manual

With accessories cover in place

Battery and accessories compartment

Right side

Left side : showing antenna connection post. It would appear that a telescoping antenna may have been an option as attested by the Sparker's hand drawn sketch elsewhere in this document. The holes are 2 inches in diameter.

Front view with cover in place.

Rear view

Nameplate

All PN1-B photos in this table by Moe Fretz

Note how the RF makes it from the chassis to the antenna connection terminal at the left  via the red  insulated wire and the thick conductor.

With chassis pulled.

Headphones and microphone.

All PN1-B photos in this table by Moe Fretz

The three crystals plug into sockets which are in the upper left corner of the photo and covered with a metal strip. In the centre foreground is the holder for the 4.5 volt "C" battery. The brown zip cord connects to the battery.

All PN1-B photos in this table by Moe Fretz

This PN1-A appears gray in colour. Mounted on the storage clips is the telescoping antenna which could be extended to 72 inches.

Closer view of the controls.

PN1-A nameplate

The 'C' battery in this set managed to survive for decades after it was installed.

Chassis underside view of the PN1-A.

With two crystals in place.

All PN1-A photos in this table by Jason Racine

PN1 TUNING PROCEDURE

1) Remove set from case.
2) Place crystals in desired channels.
3) Place 'C' battery in position and plug in.
4) Attach power cable to 'A' and 'B' batteries.
5) Plug power lead into left hand position under set.
6) Plug earphones into right hand position under set.
7) With switch set to 'Receive', turn on power switch.
8) Turn centre dial to 'B' volts . It should read 180 volts on the meter above.
9) Turn same switch to 'Trans Fil' . Now turn set to 'Send'. Turn rheostat so
     that meter above reads 2.15 volts
10) Switch to 'Trans Tune' and check crystal oscillation as follows:

With set 'on' locate screw for the proper channel on right side of set. Turn this screw until needle reads maximum and then drops off suddenly. Bring needle up to maximum again and then back it off slightly on the slow side of slope. The crystal is now oscillating properly.

11) Turn set off.
12) Disconnect leads and replace set in case.
13) Connect leads again and plug in antenna and speaker. Connect aerial at left of set.
14) Turn to 'Send' and with 'Coupling' at low side, tune 'Transmit' dial for a dip in the needle. Turn 'Coupling' up, tuning for a dip at each notch. When this dip. is located between 25 and 35 milliamps the set is tuned to resonance with the proper output reading.

This hand drawn sketch of the PN1 came from a Sparker's training notebook.

The send receive relay is operated by the Send/Rcv switch or the press to talk button on the microphone. This relay switches the aerial from the receiver to the transmitter, the filament supply from the receiver to the transmitter.

Beside being painted in olive drab as above, the PN-1 was also painted in blue-green for those units supplied to the RCAF.

PN-1 photos in this table by  Garey Valcourt

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Credits and Contributors:

1) Moe Fretz <tubetester(at)gmail.com> Collection and Preservation Of Canadian Tube Radios, Communication Equipment,  Vintage Ham gear and Military Radios.
2) Jason Racine <thebuckhunter(at)cogeco.ca>
3) Bruce MacMillan <bruce_macmillan(at)telus.net>
4) Garey Valcourt
5) https://www.ve3kbr.com/photo_albums/marconi_pn1a_album.htm
6) Cliff Chapman [chipperc524(at)gmail.com]
 

Feb 21.22