Radio Exploring the 10 Metre band 7CW station
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Page 34 RADIO, October 15, 1928.
EXPLORING the 10 ME
We publish below a full report of the work done in Australia in the exploration
of the 10 metre band of wavelengths. The new International Regulations which
come into operation next year, force the amateur still further down the scale of
known wavelengths. The 30 metre band which he pioneered and proved to the
world is now used by commercial stations, the 20 metre band is threatened, and
we find him here penetrating further into the unknown.
(THOUT a doubt the 10 metre Lictle was said about it at the time, but But, along came the Washington Con-
W band has intrigued Australian ex- every active experimenter in Australia ference which decreed that the private
perimental transmitters. For a admired their persistency. They got very experimental transmitter should have a
long time this band has been available to good results indeed, before the mysterious place “in the sun,” and a wholesale
Australian transmitters and has been left “green devil,” more staidly known as “at- slaughter of the wavebands took place.
entirely dormant. There is probably a mospheric conditions” stepped in and de- [t remains to be seen whether it will be
good reason for this, but there is creed that those § mertre signals should for better or worse (personally, I think
no excuse for any of wus for not disappear. In other States experimenters the former), but the realisation of the
having previously thoroughly investigated were at work and varying reports of necessity for immediate preparation for
its peculiarities, advantages or disad- results obtained reached this office. They these changes prompted the American
vantages, if any. Many Aus- were disappointing, however, and the § Radio Relay League to organise an ex-
tralian experimenters have spent a lot metre band remains a mystery. ploration of the 10 metre band which
of time probing the mysteries of the Not"so with its bigger brother. For a had been “generously” granted to the
spectrum around § metres with little or time it was only natural that 10 metres experimenter in place of his higher wave-
no success. The outstanding work in this should be condemned as something akin bands now wanted for the commercials.
direction was done by 2IJ and 2GW with to 5 metres and as something to avoid A few Americans, both high and
the co-operation of 2DY, who bridged like the plague. It was argued that if low power transmitters, started in
the distance between Sydney and Bowral 5 metres behaved badly, then 10 metres and effected two-way communi-
by the medium of a § metre signal. could not be much better. cation over long distances with-
out any trouble. French 8CT was
heard in U.S.A.; American 2JN in
France; 9EF worked both coasts of
America from his central location, and
publicity appeared in the columns of
QST in due course. This stirred the Aus-
tralian to activity. He realised the
necessity for co-operation in keeping
schedules and checking calibration.
Since then it is surprising.to note how
many have been quietly working on this
10 metre exploration. My request for
information from those concerned has
been very well answered, although the
response has not by any means been com-
plete. Thefirst trouble does not appear
to be with the transmitters used for 10
metres, but with the receivers. - Some
have reported that their screen grid re-
ceivers used for 32 and 20 metres cannot
be induced to function at 10 metres, and
they have reverted to the straight detec-
tor and audio arrangement.
This should not be so. The midget
receiver used at 2NO and described in
the previous issue of Rapo will amplify
at radio frequency well below 10 metres
Q The 10-metre transmitter at-7CW used the UX-852 in the T.P.T.G. circuit. - without any.trouble.. It is just a matter
RADIO, October 15, 1928. Page 35
TRE ‘BAND An
Colpitts
experimental
oscillator
for 10 metres used at
2NO. Similar arrange-
ment at SBY.
‘By 2NO-
With (ontributions from
2DY, 2HC, 4PN
5CM and 1AN
of changing the coils and away she goes.
Both the UX222 and the A442 screen
grid valves amplify well, but the A442
is the better of the two for the purpose.
The tuning is not as difficult as were our
old-fashioned low lossers, when we tried
to use them on 20 metres a year or two
ago with a tuning capacity of .00025 and
a plain dial.
two hours, so that it seems that if only The following report also received
we had an organised test with England should be of interest to some of those
on this date, something interesting might also busy on “ten.”
have happened. “Heard this a.m.: OA, 3GR, 7CS,
Observation shows that the conditions 3MY, 3GM (not sure about 3GM) and
governing 20 and 10 metres are very 2RX, who was heard by 1FT at § p.m.
much akin. The only photographs to his time Str was R8 to R9. Pse advise
hand are of the excellent 10 metre trans- 3GR and 7CS and 3MY that I heard
mitter at 7CW and a low power Colpitts them this morning.”
rig at 2NO. The latter corresponds Some others were also heard in N.Z.
with §BY’s outfit and has not at the time at good strength throughout the day. A
INSULATOR of writing been tested out. report has been received from another
As I write, excellent news is to hand source that 2DY was also heard during
from 2DY. His report on the tests is the morning. (Unconfirmed as yet.)
given herewith.
The log at 2IJ and 2DY would read
like this:—
“Sunday, September 23.
10 Metres at 2DY A.M.: Listened and called occasionally
Fig. 1.—The layout of the 10-metre Colpitts —ND.
oscillator. N Sunday, September 23, while
many of us were searching among
On the Midget the low 10 metre the crowded mass of swinging
signals from 2RX are at loud speaker waves on the 32 metre band, history was
strength continuously; 2LH is at fair being repeated “down under” on the 10
strength, as is 2UI, and many other sig- metre band. Following on the fine QSO
nals have been heard spasmodically. There by 3BQ and 6SA on 10 a few weeks ago,
is no doubt in the writer’s mind about this gives extra proof of the undoubted
interstate signals. Many 10-metre sig- value of the band. The following mes-
nals have been heard at intervals, weakly, sage received by 2DY at 10 p.m., Sep-
but it has seemed to be our luck to tune tember 23, should speak for itself:—
in during the adjustment of a transmitter “To Editor Rapio,
with a very wavery note. Held two-way communication to-day,
The strange thing is that during the Sunday, September 23, at 1.20 p.m. N.Z.
interstate tests on September 23 the time with OA3CP on 10 metres OA3CP
only signal I heard was 2RX. T noticed signals were R8 steady RAC. Regards.
that on 23 metres interstate signals were Sig., H. B. Arthur, *
very weak at that time whereas the Eng- OZ1AN,
Fig. 2.—The circuit of the 10-metre Colpitts
lishmen were rolling in at R6 and R7 for Sec., N.Z.A.R.T.. oscillator