Howard Radio Co. 225 Schematic

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Product Information:
Model:225
Manufacturer:Howard Radio Co.

Schematics Content:

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Page 1:

HOWARD PAGE 9 9
HOWARD RADIO Co. s?h@m<=1?,?r?1ea?e '
_I B W .... mil og
(C)John F. Rider, Publisher

Page 2:

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THE I. F. S'1'AG?
The I. F.'s are aligned oy the usual system of feeding the intermediate
- _ - - - - frequency or 465 KC into the grid of the SA? tube.
' The two trimmers in each of the I. F. cans should 'oe very fully peaked
RF to resonance as they are vary critical and will yestly effect the performance
, ' , of the egg. ghese are trimmers number TB, T9, Tlo, 111. (see pictorial dia-
R; . ' The Sensitivity of the I. F. stages will be 25 to 50 mlcrovolts or better
for a 50 milliwatb Output.
_1 __ ff/ Always use as lon an output as possible from th test oscillator in ln;
?5"~ __ - ' Q (D the vartous adjustments.
'etifo-_ 2,22 rust check one pceatlon or me fuel nano by rotating one condenser shaft
j U b S'? `S to the left to full capacity. At this point the dial d should be strsimt
1-., -y.. -r, 15 across in line with the lines dividing the scale ln half. It the hand is nf!
A position it can be lined up by removing dial glass and setting hand with screw
S :. ln center or dial.
S 5 1. Set the test oscillator to 6 megacycles.
5 t 2. Tum wave band switch all the way to right for Police &nd, and .set dial
' y hand to 5 H. C.
\ - ` 5. Peel); trimmer; condenser T4 of the oscillator coil Fig. 2 to reso ce with
6 . C. e into antenna.
__ _ _ _ _ _ _ ,_ _ _ _ __ __ _ __ ._ 4. Adjust antenna coil trimmer T2 to some frequency after the above mentioned
-,-up vmw 225' 5?',z25',?5,_, oscillator trimmer has been set.
FIG l. BROADCAST FIG 2 ORFIG Z
|.|;?'v"",f",'1"__- ,QQYQQ =';_',{',j - 1. Turn mve Sand switch all the way to left and dial hand set to 1400 KC (the
I 2. Peak oscmllstor cr r 'rs to 1400 xc and antenna cr r 11 to sans
= O C SETTGH K Z. 8% dial to 600 KC and adjust oscillator padding condenser 'IB to 600
_ " ' 4. Recneox cual et 1400 Kc ea an number (1) ann (z).
VOLUME LUIIYRCH.
ml convumw. e?. -rms 5. Points in the middle of the dial my be checked and if necessary the plates
?'""-" $1.1 teena. of the front section of variable condenser may be bent for alignment.
C'l (C) | 1.. Seal all tr rs after their final adjustment. _
neue: une, ,Wa _ /ZZ," 2. Be sure that the settings are being mde to the true tsl signal
?"-=?'~ -'el egg; __' from the oscillator and not on e harmonic or image frequency
an 're Gm. "*'~ T, The models Z5 and 250 are electrically the same chassis; the only differ
ence being the cabinets ln which they are mounted. These models have two d
,?v,,,,, circuits covering the Broadcast Bend 550 to 1700 KC and the a lled Police
nm g O `\,&r:?-_*ml :Qld from 2 to 6.5 megacycles, having ss te Antenna and Oscillator coils for
KL ! Bhortfhgvrrcgg ????tanz?e5% cover the Broadcast Band 550 to 1700 KC and the
ffgnvc O The models _&0 end _ggg have the same circuit or the 225, S225 respective-
ly with the addition of the tuning eye tube to indicate resonance;
>> r, 3 C The models QL5, QQ and 280 are the electrically, covering 5 bands,
4, .,, ow W I asc to lvoo xc, 1.7 to 5.5 rc, and 5.5 to ls rn.
Ch mod
c ( ' G O about 15 to 30 mcrwoltgu Ol' 8 B18 described in this folder N111 be
to be obtained from the models 225 250 260 1 wil
' "" " M #444 A W *bg* -25 mite- The undlatorted oucpuc about 1-1/2 ,-.EUR,t?B_' S" 9
501-1-UM* vlzw _ Zn' Z5a_Z?? 4 muse 275 series will give you a 1 output of 5 watts, undlstorted abou
FIB Z '
(C)John F. Rider, Publisher

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