Service notebook of Harold Gordon Cornell - 1917 - Part 19

(13)

The object of this is to detect "Sparking"

Any leakage detected is to be remided xxxxxxx

immediately.

LOG. The operator i/c machines will keep a 

log book setting forth details as under

which will be recorded daily.

 

 

(14)

General Routine

When a machine is detailed for wireless 

practice the operator i/c machines will see

that everything appertaining to the wireless

installation is is readiness at least ¹/₂ hour

before specified time of flight.

 

Before the machine leaves the ground he will

explain the use of the safety plug to the

occupants of the machine.

 

When the machine leaves the ground the

operator xx i/c machines will "tune in"

at the aerodrome wireless station and put

out the signal "K" to proceed if wireless is 

working properly.

 

Directly a machine carrying wireless returns to

aerodrome he will go to it at once

overhaul set clean contacts &c.

 

The operator i/c machines is ON DUTY until

all machines carrying wireless are in 

 

(15)

HINTS FOR WIRELESS OPERATORS.

The Stirling Transmitter.

1 The platinum contacts must be absolutely

flat and true when they meet to avoid loss

of efficiency in set and eventual

destruction of contacts.

2 The iron core should be so arranged

as to get an even pull on the blade.

The Core must be true. If necessary

to true up core file it.

4 The rubber adjusting stud.

When this is screwed up more tension

is put on the blade. This nut alters the

current through set.

MINIMUM CURRENT Screwed down

MAXIMUM CURRENT Screwed up.

x3 Adjusting note Remember that the nearer

the core the blade is adjusted the higher

the note.

5 The spark gap The aluminium gets "Pitted"

and the probability arises of uneven

sparking which spoils note.

The spark gap device needs constant trueing

and polishing.

6 The spark gap chamber becomes filled with

metal dust and this may cause "arc-ing"

To avoid losses due to arc-ing occasionally

clean and shellac spark gap chamber.

7 Tuning clips. Observe carefully that these do

not become "spread" and so "short" the in

inductance coils.

(16)

8 Adjusting set You want to get as much

current as possible through set without xxx

excessive sparking at the contacts.

The current should be of a value as  

nearly approaching 5 amps as possible.

9 To adjust spark gaps remember that the

wider the spark gap the longer the time

the condenser takes to charge and the

greater the sparking at the contacts.

Remember not to set the spark gap at its

maximum because the set has usually to work

for several hours. Adjust the gap rather on 

the small side.

take steps to avoids excessive sparking

at the contacts.

              WIRING MACHINES.

Use U3 for key leads

  "     P11 for earth leads

  "     P3 for aerial lead.

              AERIAL WIRE.

When unwinding aerial wire R4 from a drum

always let drum unroll and so avoid "kinking"

the wire. Losses of aerials are often due to

"kinked" or bruised wire.

Dont use pliers too much when twisting up R4

use your fingers and thus avoid kinking

bruising and similar damage due to twisting.

Dont bend the wire round the hook of the

aerial weight. It will soon wear there the use

of a brass thimble will tend to overcome this.

Issued by officer i/c Wireless

24th Wing R.F.C.

Spittlegate

SCHOOL FOR WIRELESS OPERATORS R.F.C. NOTES ON MK/3 TUNER etc.

1 Ordinary aerials are150 or 125 feet long from tuner to

free end.

(2) If your aerial is 150 ft long you will find the following

notes for "stand by" fairly exact. Place coupling at

loose and secondary condenser at 'O' in order to avoid

absorption of energy by secondary circuit. Place primary

inductance on stud 6. If you were attached to a squadron

whose wave lengths were 160 180 220 and 250 metres those

wave lengths would come in about 6 12 30 and 48 on the aerial

tuning condenser provided your aerial was of the above length

(150) ft. If your aerial is 125 ft long from tuner to free end

and the squadron wave lengths xxx are 140 180 and 220 metres

these will come in about 2 20 and 70 on the aerial tuning

condenser. If you compare the two sets of figures given

above you will see that the smaller aerial has considerably

less capacity than the larger aerial and this entails the

addition of greater capacity in the aerial tuning condenser

to cover a certain range of wave lengths. The above information makes the picking up of machines a very simple matter.

if you are attached to a field artillery or to 60pdr batteries

whose chief duties are firing upon NF or GF targets you will

be chiefly concerned with picking up area calls. For this

purpose you will use "stand by" side only and the aerial tuning

condenser must be kept constantly on the move over the number

of degrees necessary to cover the wave lengths in use on

your front.

(3) When you switch over for a shoot always try retuning your

primary by decreasing inductance and increasing aerial condenser.

Very often two or three studs of Primary Inductance and large

condenser will give the best results. The tuning of the

secondary is a very simple matter as you know from the position

of your aerial tuning condenser what wave length you are receiving

and you have only to read off the same wave length on the

Calibration card inside the tuner to get the correct adjustment

for the secondary circuit. If there are several alternative

readings given for a certain wave length on the calibration card

you should select that reading which gives the maximum inductance

combined with the minimum condenser to get the loudest signals

on the secondary.

(4) Crystals. Both perikon and carborundum give the best results

with a light contact. A sure sign of a dud operator is a collection 

of crystal chippings underneath the perikon detector due to excessive

tension on the spring. If you can get no result out of the

carborundum it probably means that rust has formed on the

underneath of the steel blade or that 3 volts is insufficient to 

reach the rectifying point of the particular crystal you are

using. The formation of rust must be avoided by polishing the

steel blade every day and the crystal can probably be made to

rectify by connecting all four cells in series. This will

give 6 volts in which to reach the rectifying point and will

be found effective in the great majority of cases. If the

Carborundum still refuses to rectify the signals you should

ask your squadron officer for another crystal.

 

If you are using 6 volts on the carborundum you should tap off

at 3  volts (i.e. 2 cells) for buzzer and this will make it

necessary to adjust your carborundum on a signal not on the

buzzer. To find the most sensitive point on a crystal by the

buzzer-- place coupling at loose and adjust your two circuits so

xxxx that they are badly out of tune. The signal can now only be

heard when the crystal is in really sensitive adjustment.

(5) The great secret of success in wireless is to keep all your

contacts and your instrument scrupulously clean, Remember that

dirty contacts intruduce unnecessary resistance into a circuit

where the total pressure is only a very small fraction of a volt.

such unnecessary resistance  will cause weak signals and may

result in total failure. When you get to the front make up your

mind to wipe your instrument and all contacts over with a rag

at the close of each days work and to close the lid for the night.

A drop of petrol on a rag is of great assistance.

If the joint in your aerial where P-11 joins the R4 is not

soldered it must be cleaned at least once a week and carefully

protected by insulating tape.

xxxxxxxxxxxxxxx

xxxxxxxxxxx have been found useful:-

(1) xxxxx the coupling and make

"NOTES  ON JAMBING"

The following hints have been found useful.:-

(1) Loosen the coupling and make sure that both your circuits

are dead in tune. Remember that when you vary the coupling

you automatically alter the capacities of both circuits

and both will require very s-light retuning.

(2) If this is insufficient retune the secondary by reducing the

inductance and increasing condenser. This tends to weaken

signals but sharpen tuning.

(3) Remarkable results can sometimes be obtained by placing

inductance switches so that they make contact with two studs at

once retuning the condensers at the same time. This should be

regarded  as "freak" tuning" and should not be made standard

practice.

(4) Try varying potentiometer when using carborundum. You can

sometimes  bring up your own signal and reduce others by this xxx

means.

Procedure for "Tuning-in" preliminary to a shoot.

(1) Listen in on "Stand by" side as directed above and tune

primary exactly Time necessary 5 secs.

(2)xxxxxxxxxxxxxx

(2) Having noted approximate wave length on primary read off xxx

ditto from calibration card switch over to tune and find best

adjustment, Time necessary 15 secs.

(3) Re-tune primary circuit as directed. Time necessary 10 secs.

Ground strips must not be put out till all tuning is completed.

All operators will have to "tune-in" to a "call" from a

wavemeter and key in 45 secs before joining the senior group

of squads.

The coupling handle moves from 0 degrees at "tight" to 90 degrees

at "loose". The coupling handle will never be at less than 20

degrees. 45 degrees will generally be about right but good

operators always work at loose if the signal is audible there.

The change over switch must be put over gently.

It will be damaged by rough treatment.

Sgd. J.B. Bowen, Capt.

Commandant school for wireless oprs.

R.F.C. Farnborough.

 

MEMORANDUM OF WIRELESS CONFERENCE HELD AT H.Q. NORTHERN

GROUP COMMAND ON MONDAY 21st MAY 1917.

Present Capt. E.S. Perrin Capt. N. Gill. M.C.  Capt. A. Gouldwell

Lieut J.E. Marriott. Lieut. S. Allenby. 2/Lieut W.J.R. Sheppard.

and Meeting held at H.Q. Training brigade on Wednesday 23/5/17.

Present ..... Major A.ap Ellis. Capt E S Perrin.

Buzzing. With the exception of the 27th. Wing the buzzing classes

of Squadrons at one station will be centralized in one

instructional hut. The morse inkers will be in the same hut.

In the 19ty. Wing the accommodation for Buzzing

was stated to be insufficient. The question of increasing

accommodation is being taken up but in the meantime the

existing accommodation will be laid out in the best advantage

to conform as far as possible with the ruling laid down in

the first paragraph.

In the case of the 27th Wing where xxx there are fo

four squadrons widely separated at one station the buzzing

will be centralised in two instructional huts as soon as two are

available. In the meantime it will be centralised in the

one existing hut.

Buzzing classes will not be held in the wireless hut

at any station.  Where timber is available benches will be

erected on both sides of the instructional hut. If timber is

not available tables may be used but they will be arranged

down the sides of the hut.