The Washington herald., 1922-09-03
DISTRICT AMATEUR
REPORTS SUCCESS
E0F new INVENTION
!. Mertens Demonstrates
Practicability of Hook
Up Form.
Used THREE TUBES
,oncert In Schenectady Heard
Plainly Without Aid
OF Phones.

Interest in experimenting with
he Armstrong super-regenerative
ircuit has not waned in spite Of
ne fact that the majority Of radio
|ans have experienced difficulty in
bbtaining what might be called sat
sfactory results. Complications in
wiring diagrams. scarcity OF parts
Needed. tedious adjustment Of ap-
baratus and the apparent need for
masters hand when the apparatus
assembled have combined to
Ehwart the best efforts of many
tkilled radio technicians, not to
mention hundreds of persons who
have a fair knowledge of radio to
Encourage their attempts to build
Ind operate the new circuit.
One Of the local radio fans who
has demonstrated the practicability
NJ the hook-up for amplifying local
koncerts and for tuning-in o"t-of-
kown stations to the exclusion OF
local broadcasts is +. Mertens, jr.
dertens used three tubes and ap-
broximately the identical circuit
shown in The Herald several weeks
kgo with accompanying values. The
rriter listening-in on the set last
Tuesday night heard wGY Schenec-
ady. as plainly as a local concert
Ind local concerts tuned out for the
reception of distant stations. The
nusic was clear and at times loud
Enough to be heard across the room
rom head phones Interference and
Ftatic were almost eliminated. In
teviewing his work with the circuit,
Mr. Mertens stated:
TrosbIed my Filter Circuit.
"About July 10 started building
super-regenerative hook-up as
published in The Herald. Certain
alues given did not operate salts
factorily. hence changes noted were
nade. The greatest trouble was
aused by the filter circuit. In
luded in this part of the diagram
had used an iron core choke coil
90 NH inductance. and two $4,000
bhm resistances. II was found that
1900 DL coil could be substituted
Tor the 100 NH iron core coke coil.
md that a 400 DL coil could be used
Satisfactorily in place of the ; NH
Spen-air choke coil. Three VITA
ubes were used.
"I experimented long while
With inductances. At first a vario-
Eoupler made from the windings OF
variometer was used ahead of the
trst tube and gave satisfactory re-
|nlts. A change was later made by
Substituting $50 degree vario-
eoupler, the rotor of which was
Eound with approximately 100 turns
" No. 2s wire. This gave excellent
tsxuIts.
s''Radiotrons 2Ol were then used
Tor. the last two tubes in the cir
hut. but these could not be sub
3fituted for the tube used as de-
ector.
= FreauenfIy Changes Batteries.
The c battery values used were
hanged frequently until better re-
ults were obtained. Four and one
hEh volts for the first two tubes
md approximately eighteen volts
,n the grid Of the last tube the
atter feature differed from the pub
ished circuit.
much credit is due to J. J. Mac
Ereger and l. n Gebhard. radio
[echnicians Of the Naval Air sta
iop for the successful performance
* the set. We have listened in to
NSB. Atlanta. Ga: wGY. Schenec-
sdy. y. Y: WHAS. Louisville. KY.
kpd to other distant stations. These
we're regularly tunedin In spite of
zeal transmission going on during
Inc same hours"
Although the set operates eff
fently IL IL sensitive and requires
kceurate adjustment to secure re-
Iuits which Justify its use in place
~ the ordinary regenerative re-