Receiver—Type 3V-DR-3
The photo and instructions are from the "Operating Instructions for Automatic Radio Beacon Equipment--Department of Marine, Radio Branch 1930". The long pages don't fit into my scanner. This is a three tube regenerative receiver: one detector and two stages of audio amplification. The following text is taken directly from the equipment manual and gives some insight on receiver tuning. In the illustrations above, the three vacuum tubes have been removed for clarity--the four pin sockets remain.
As a further note, the sequenced radio beacon equipment was devised as an assistance to mariners. For example three radio beacons could be scattered along the coast all transmitting on the same frequency in sequence. Only one beacon would be transmitting at any one time. A navigator could tune is radio direction finder to the sequenced beacon frequency in his area and, as each beacon transmitted for its allotted 3 minute interval, could note the bearing of each. Applying the bearings to his chart the navigator could be assured his position was where the three lines intersected, sometimes call the 'cocked hat', as they seldom intersected, but usually came close, leaving a small triangle of error--hence the name. If the beacons were not sequenced, they would be transmitting continually on three different frequencies, requiring the navigator to tune to each station in turn. Sequencing was economical on frequencies used, and reduced navigator error.
Each beacon had its 3 minute transmit window, thus it was important to ensure the mechanical clock timing was accurate to ensure only one station was ever on at any one time. The station's clocks were checked regularly against the time 'ticks' from the US Navy Station at Arlington, Virginia. Thus the requirement for a good receiver.
The above illustrations show the new receiver for use on Beacon Stations.
At the bottom left of the panel is
located the filament switch plunger which must be pulled out to put the set in
operation. Always push the plunger in after using the receiver. At the bottom
right of the panel the phone jack, marked “out put”, is located. The head-phones
should be plugged into this jack. At the top centre of the panel is located the
range switch. When this switch is in the “short” position the receiver will
function from 500 to 730 metres, and the “long” position gives a wavelength
range from 2,400 to 3,000 metres. The reaction is controlled by the knob in the
centre of the panel, while the aerial tuning is controlled by the left hand
dial, and secondary tuning by the right hand dial.
The aerial tuning may vary greatly on
different stations and the Secondary tuning will vary slightly, but on a
standard aerial the Secondary tuning dial, for reception of NAA (Arlington) time
signal, should be set at approximately 36 with the range switch in the “long”
position. The aerial tuning and reaction controls may be in the neighbourhood of
55 and 40 respectively, but these adjustments may vary greatly according to
local conditions. Arlington should be received at good volume by all East Coast
and Great Lakes Stations, and over the entire length of its two ranges the
receiver should be found sensitive and easily controlled.
The battery connections are made to suitably engraved binding-posts at the back
of the receiver.
The receiver is intended to use UX 201 B
tubes with an A battery of 6 Volts. The B battery should consist of two 45 Volt
blocks.
Arlington Time Signal
Commencing at 11:55 a.m. E.S.T., NAA sends a series of 29 dots at intervals of 1 second. This makes the 29th dot coincide with 28 seconds past 11:55. On the 29th second there is no dot, but commencing at the 30th second NAA sends a series of 25 dots at intervals of 1 second. This makes the 25th dot of the second series coincide with the 54th second past 11:55. No dots are made on the 55th, 56th, 58th and 59th seconds, but at 11:56 NAA commences another series of dots. Each minute thereafter until 12 noon is similarly marked with the exception of the second series of dots in the last minute preceding the hour. Commencing at 11:59 ½ NAA sends a series of 20 dots at intervals of 1 second, the 20th dot coinciding with the 49th second of the last minute before the hour. From the 50th to 59th seconds NAA is silent and on the 60th second—12 noon E.S.T.—he makes a dash. This completes the time signal, which is repeated at 9:55 to 10 p.m., E.S.T.
Tracing Faults in Receivers
If Receiver is noisy, see that grid-leak
is firmly in its clips and that the grid-leak end pieces and clips are clean.
Examine all receiver binding-posts and see that they are screwed down tight.
Examine battery connections and see that they are tight and clean. Using spare
tubes, replace the tubes in use—one at a time—to ascertain if any of the tubes
in use are noisy. Replace the batteries in use by spares to ascertain if the
batteries in use are noisy. Examine the aerial tap connections on the two aerial
tuning coils and make sure that the spade terminals are securely screwed down to
the small brass posts. Examine all soldered connections making sure that they
have not become disconnected or crystallized. Using fine glass-paper, clean the
contacts of the Short-Long switch. Check over the tuning condensers for
alignment and make sure that there is no dirt or dust between the plates. Clean
out the spark-gap by passing a piece of stiff paper between the points. Move the
filament switch out and in several times, turning the plunger around while doing
so, to clean its contacts. Make sure that the phone jack is making good contact
with the phone plug, and that the phones and phone leads are in good condition.
If no signals or only very weak signals
are heard, check the condition of A and B batteries. See that the aerial and
ground connections, all battery connections, all soldered connections, the two
aerial tuning coil tap connections and phones are O.K. See that the spark gap is
clean and not shorted. See that all tubes are alight and in good condition. See
that the .005 mf. condenser across the first AF transformer primary is not
shorted. See that the tubes are alight and in good condition. See that the .005
mf. condenser across the first AF transformer primary is not shorted. See that
the Long-Short switch is making good firm contact at all points. As a last
resort, unsolder the two AF transformers and check their primary and secondary
windings for continuity. Should the 2nd AF transformer show an open circuit it
may be left out of circuit, in which case the phones should be connected between
the +90 volt terminal of the B battery and the B 90 + binding post of the
receiver, and the third valve should be removed from its socket. Should both
transformers be defective the receiver may be used with one valve. To use the
receiver with one valve removed the last two valves from their sockets. Remove
the two A.F. transformers from circuit. Connect 67 ½ volts of B battery to the B
45 + binding post of the receiver, and connect the phones from the B 45 +
binding post of the receiver to the end of the reaction coil not connected to
the Detector plate. Make no connection from the 90-volt B battery terminal to
the B 90 + binding post of the receiver.
Continuity Testing, AF Transformers
Use the Weston type 279 voltmeter and
a No. 6 dry cell. Connect one terminal of the cell to one terminal of the
voltmeter. To the remaining terminals of the voltmeter and cell, connect two
twelve-inch lengths of wire. When the ends of these two lengths of wire are
touched together a deflection should be noted on the voltmeter. Test the
transformers by placing the ends of the two test wires on terminals B and P of
the transformer. In no deflection is noted on the voltmeter, the transformer
primary is open. Next place the ends of the test wires in firm contact with the
G and F terminals of the transformer. If no deflection is noted on the
voltmeter, the transformer secondary is open. If either primary or secondary are
open the transformer in useless.
Immediately phones, valves, transformers,
etc., are found defective, replacements should be wired for, and the defective
apparatus should be returned at first opportunity to Headquarters.