Meissner Mfg. Div. - Maguire Industries, Inc. 4E Schematic

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Manufacturer:Meissner Mfg. Div. - Maguire Industries, Inc. (Brewster)

Schematics Content:

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Page 1:

The Meissner Model ME T R F Bandpass Tuner is designed for superior high
fidelity broadcast reception It is specifically designed for custom in
stallation and may be used in connection with a power amplifier and speaker
sfstem to fit a wide variety of installations ranging from the simplest
home installation consisting of a low power amplifier and a speaker, to the
largest high power installations designed to serve large auditoriums and
consisting of one or more high power amplifiers and multiple speakers
The Power Amplifier
The output impedance of the ME Tuner is 100,000 ohms and should be worked
into an amplifier having high impedance input High impedance amplifiers
usually have an input impedance of Soo OOO ohms, but some have a lower 1m
pedance than this and the ME may be worked into an impedance as low as
lOO 000 ohms with no appreciable loss of low frequencie or increase
distortion An amplifier having provision for phonograph input from a
crvstal pickup is satisfactory for use with the ME, but under no condit
ions should the be worked into a microphone input channel The relat
ively high output of the would cause overloading nd severe distortion
in the microphone input stage and the hum level would be too high to be
considered acceptable
The Cabinet
One thing that should be observed in planning an installation is to use
the normal precautions against microphonics Since the LE a T R F c
cult and has no local oscillator, its tendency toward mocrophonism will be
much less than in a similar superhet unit; but the 6AT6 audio amplifier
tube may produce microphonics if subjected to severe vibration. This vib-
ration may be transmitted through the cabinet or through the air from the
speaker and the installation layout should be planned to avoid it.
The Record Player (or Changer)
The phonograph system of the chassis is designed for use with crystal
type pickups, and any record player or changer having this type pickup may
be used. The following notes should be observed:
l. The record player frame must be connected to the tuner chassis in order
to prevent hum pickup. ln some record players the connecting lead from
the phonograph pickup cartridge to the tuner chassis is a shielded lead
with the shield connected to the pickup cartridge and to the record player
frame In this case the record player frame is au?atically connected to
_the tuner chassis; but in record players which do not have this connection
`a separate connecting lead between the record player frame and tuner may be
2. The record player motor may be plugged into the convenient outlet on the
rear of the tuner chassis. A power switch must be provided on the record
player to turn the motor on and off.
3. The connecting lead from the ickup cartridge must be provided with a
miniature phonograph plug. The EE chassis is shipped with a proper plug
in the input jack for use on phono units not so equipped. The outer band
or shield is connected to the shell of the plug, end the center wire is
/,` soldered in the pin of the plug.
?J'ohn F. Rider

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ln c1rc11ts formerly employlng a small value of f xed condenser across the
output transformer as a permanent m1HlmUm tone ccntrcl lt lS desirable to
out this capaclty to approxlmately one half lts former value when the 10
kc fllter lS added Pentode anpllflers usuallJ employ such condensers
Trlode ampllflers seldom u e such oondensers, but lf they do lt lS well to
reduce thelr value to half
Allgnment Procedure (use 200 uuf dummy)
1 US1HQ an F M Slgnal Generator and Oscllloscbpe
Connect the vertlcal plates of the oscllloscope to the Ch8SSlS and top
the volume control Connect the horlzontal plates to the sync termlnals of
the F M slgnal generator
Set the dJal of the tuner to l, 00 kc and the generator to l hoo kc uslng
put of the generator tc he lea t that wlll g ve useful plcture, connect
lng generator to antenna te ll al
Adjust the trnmmers at the top of the gang condenser to obtaln a pat
tern of the greatest amplltude, TEURdUC1Hg generator lnput as allgnment pro
ceeds, and at the same tlme adyust ng the tr11mer tc glVEUR a double humped
pattern wlth humps of eotal maenltude and wlth the center of the pattern
centered on the scope
2 US1Hg an A M Slgnal Generator
Connect the slgnal gen rator as usual, wlth an output meter as lndlcator
connected to top of Volume control or
Set generator at l 355 kc nd tuner
on top of the gang and slowly tlghtcn
output readlng Keep each trlnmer on
wudlo cable
t l 00 k Loosen the M trlmmers
one at a tlme to obtaln a maxlmum
the loose slde of resonance until all
TPlmmEURTS are nearly peaked ther carefully eak each trlmmer Check align
ment by slowly tunlng generator to about l l5 kc durlng whlch the output
meter should show a sl; ht drop and then arlse agaln Th1S allgnment cen
ters the response at l OO kc o that the d1al callbratlon wlll be accurate
If the generator had been set at l O0 kc lnltlally, the center of the tun
e 's respon e would be below l OO kc on the tuner dlal
Res; tance and Voltage Chart
Reslstance between pin and ch ssls
SAT6 Detector
Pln Number
l meg 0 5 meg 5 meg 70
70K 0 5 meg 5 meg 70
l meg 25 O 25 9 K l TK 5 meg
2 O Tie Point 0 25 0 25 Tle Polnt 240 meg
Readlng subject to posltlon of hum balance control
Read1ng subject to v rlatlon dependlng upon the fllter condensers
CAUTION: D1SCh8Pg9 fllter condensers before mak1ng measurements.
Voltage between pin and chassis.
No signal condition.
Measurements to ground with 20 OOO ohm volt met r, l OOO ohm volt
6AT6 Detector Sl.Neg. >>~
6 Rectifier
185 VAC Tie Poift a Tie Point 18a vAc 2
i3eading will range from O to 6,3 volts AC depending on setting of hum
Pin Number
Sl Neg Sl Neg
a sweep freouency of boo cycles and deviation of about i5O kc. Set the out-
?John F, Rider

Page 3:

,-\ General Service Data
Power Supply llO-l2O V 50-60 cycles.
Power Consumption 25 watts.
Undistorted Output 2 to 15 volts.
Replacement Part Numbers - as shown on circuit diagram
Circuit T.R.F. Bandpsss.
Audio Frequency Response - flat i2 db. to to 15,000 cycles.
Hum Output .OO2 volts.
Tubes: 6EA6 R.F. Amplifier 6AT6 Detector - Audio Amplifier
6BA6 R.F. Amplifier 6Xh Rectifier
lO-kc Filter
/~\ In the case where two strong broadcast signals are received on adjacent
channels, a 10-kc beat note is formed by the two broadcast signals heter-
odyning together and when this happens a broad band, high fidelity receiver
or tuner will pass this 10-kc beat note and produce an annoying high pitch-
ed whistle in the speaker.
The Meissner 10-kilocycle filter is designed to eliminate the lO-kc whistle
between stations being received on high-fidelity radio installations. This
filter has several points of superiority listed below:
l. It is placed in the output stage where it will not pick up hum voltages
from filter chokes and power transformers, a common fault of high-impedance
filter sections connected one or more stages ahead of the output tube.
2. It employs two filter circuits instead of the single circuit usually
used, producing far greater attenuation of the l0-kc note than a single-
section 'filter can produce.
3. It requires no tuning, being manufactured of close-tolerance circuit el-
ements of fixed values.
M. Requires a minimum of space for the attenuation produced, both filter
circuits being placed in the same can but shielded from each other.
5. Can be utilized efficiently in either pentode or triode circuits.
6. Works well with a single tube, or two identical filters usable for a
7. Current-carrying capacity of 75 ma. permits it to be used in any receiv-
er and in all but the very high power Public Address systems.
White Blue Blue White
f"' ; | To Speaker : H To Speaker
, : Voice Coil I c,T Voice Coil
Red e
E ----- -- ;iR@d To Speaker Red; ___-J To Speaker
B+ I ____ ___ :Red Voice Coil BRe?g_______' Voice Coil
white' ?"'" ` ' Blue Blue White '
NOTE: G = approx. l/2 original fixed l
tone control capacity.
? John F. Rider

Page 4:

(C)John F. Rider
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