Lafayette HA 410 Owners Manual

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TABLE OF CON'I'EN I'S

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bPhCIFICATIONS ................................................

GEXERAL DESCRIPTION ......................................... 5
INSTALLATION ................................................. b
OPERATION .................................................... 7
THEORY OF OPERATION ........................................ II
TROUBLE SHOOTING HINTS ..................................... l4
RETURNING THE UNIT FOR REPAIR ............................. IS
SHIPPING INSTRUCTIONS ........................................ 15

ALIGNMENT ........................................... . ........ 18

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illmm; UV UPI» :Mmluk

lié' R0 D U C l' lON

The folluxxing presentation of tin. 1(er l of Upclntlfll. fov" the HA ll lldlrSCViVA r .> Ilivirlwl in?»

{our parts. The first part duals, with tln up,» Mum of this v-ccwwcr portion n! two (human

The >ecmul part discuss. on for the {rarinvnitlt'l port? m m [in lfd:1> The third part outlines the pew

puwe r indicator.

vs the tintnry of Opera
:x' supply .31Jl thy lourtn part Goals with the S-Mr'Lc'JRvilltixw

REC EIV ER

Refer to the receiver block diagram (Figé) while reading the following. If greater rletnil is riir
sired, refer to the schematic diagram,

V1 V2 V3 V4) V3
mt 1" avasxc 2nd 455m m I; m I;
Am, mxen mxzn Amp AMP fl
ancs " K1 VAmAaLE XYAL
FILTER 1 LOCAL LOCAL
I use | 05:: 2 1
mums :3 6'3:
22.255 10 T X '-
23355 MC =
Avc
V6(P)
POWER
AMP
V7) vs (T)
To SPKR <-
ourPuv PHASE Aumo
XFMR mvEnTER PREAMF NL EVE;
V7(P)
IS72 mso
POWER
AMP
TO
F
s MEYER
FIGURE 4-RECEIVER BLOCK DIAGRAM NOTE (P)=PENTODE SECTION

4T1=YmonE SECTION

When an RF signal is applied to the antenna of the transceiver, it is fed through the harmonics
filter and the change-over relay Kl to the input of the RF amplifier (V1). The RF amplifier
(V1) is a loquoise Nuvistor stage.

After amplification by the RF amplifier stage (V1) the RF Signal is fed to the grid of the lst
Mixer stage (V2). The lst Mixer stage (Vd) is the pentode portion of tube Vi. The triode sec»
tion of this tube is variable local oscillator l. The frequency of the local oscillator is deter-
mined by the setting of the RCVR TUNING control and it can be varied from £1155 to 23.95::
MC. The output of local oscillator 1 is fed to the grid of the pentode portion of Vi where it
mixes with the incoming RF signal. The output of the lst mixer stage is tuned to the first in4
termediate frequency which is the frequency difference between the two signals applied to its
input.

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The output of the first mixrr Vi is fed to tho grid of tho pcntodu portion of the find mixer (V5).
in trio (1 c portion of V5 is a 6.1 MC crystal oscillator. The output of the 6.; Mc crystal
oscillator is fed to thy grid of tho pcntudc portion of the ind mixer V3 when: it combines with
the 5745 Kc signal fcd from the lst mixer VZ. The output of the 1nd mixer V3 is tuned to
455 Kc \xhich is the second intermodiatc frequency.

The output of the find IDIXLI stage V5 is fed through two stages of IF amplification (V4 and V5)
and than to a lNoO diode detector. The leO diode detector rectifics the IF signal to produce
the audio signal and the AVC voltage.

After filtering the AVC voltage is applied to both 455 Kc IF amplifiers, the second mixer, and
the Nuvistor RF amplifier to provide automatic volume control.

After filtering the audio signal is fed through a self~adjusting automatic noise limiter to the
VOL control. From the volume control the signal is fed to the input of the first audio amp1i~
fier V7. After amplification the audio signal is fed to the grid of the triode section of the phase
inverter (V6). The phase inverter processes the audio signal and feeds it to the grids of the
pentodc sections of two tubes (V6 and V7) which operate as push»pull power amplifiers. The
output of the push-pull power amplifier is fed to the primary of the output transformer (T5).

The secondary of the output transformer (T5) has two windings. One winding is used to drive
the receiver speaker. The second winding is used to modulate the transmitter when relay K3
is in the proper position.

7.0 to
7,425MC VIOW Vlom vam vsm v9
VFO osc BUFFER 7.0To m FREQ me To End FREQ 28.0 Y0 RF POWER To
7425M: DOUBLER 14,950Mc DOUBLER 29.7w OUTPUT MAT
xm. RELAYIVE
D 7,0 T0 POWER
T 7.425MC METER
7 NOTE: (P)=PENTODE SECTJON
(Damon: SECTION Vé'P
powsn
AMP
V4) V6) V7(Tl
MOROPHONE 2m: PHASE OUTPUT
PREAMP PREAMP INVERTER xmn
V7fP)
POWER
FIGURE S-TRANSMITTER BLOCK DIAGRAM "P

TRANSMITTER

Refer to the transmitter block diagram Figure 5 while reading the following. 11' greater detail
is desired at any point, refer to the schematic diagram.

The transmitter signal is generated in the pentode section of the oscillator/buffer Stage VlO.
The oscillator may be either crystal-controlled or used as a VFO. The triads section of the
oscillator/buffer stage VlO is a buffer amplifier used to isolate the oscillator from undesirable
effects which might be caused by the loading of the following circuitry, The output of the buffer
amplifie r V10 is fed to the input of the first frequency doubler stage V8.

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