26
3.
SERVICE
DATA
3.1.
C i rc u it desc ription
3. 1.1. HF·OSCILLATOR
( F ig. 25)
The frequency of the h.f.-oscil lator is determi ned by the resonant ci rcu it, wh ich can be switched separately to
the col lector c i rcuit of transistor 30 1 . I n conjunction with transistor 302 self-excitation occurs at the oscil l at ion
frequency due to positive feedback. The amplitude may be adjusted with potentiometer 6 1 2.
Transistors 30 1 a nd 302 are coupled via an automatical l y controlled and regul ated current source 305/306.
The ampl itude of the osc i l lator is stabi l ized via this current source. The requ i red control voltage is obtained by
rectifying the output-ampl itude of separating-amp l i fier 303/304 by diodes 406 and 407. Diodes 404 and 405
serve for temperature compensation.
The begi n- and end frequencies of every range are tuned with adjustable coils and capacitors; adjusti ng is
fac i l itated by using series and parallel capacitors. With triple tuni ng capacitor 599, five ranges can be calibrated
on two scales; the frequency response of the rema i n i ng fou r ranges is m arked on separate sca les. Both i .f. ranges
-
0.4 ... 0. 5 M Hz and 1 0.3 . . . 1 1 . 1 M Hz - have separate scales.
The sca le, corresponding with the sel ected frequency range, is ind icated by one of the six LED's 491 . . . 496.
769
527
6
'
7
C>
302
303. 30"
516
-
12V
-12V
",$ '""
DC
511-613
HF
"06 .
,
.
0
7
-
�
8 v
- 18 V
MAB2i8
Fig.
25.
HF- Oscillator
Содержание PM5324
Страница 1: ...HF Generator 100kHz 110MHz PM5324 9452 053 240 1 9499 450 05511 730801 1 01 ...
Страница 15: ...14 Fig 4 Front view Fig 5 Rear view ...
Страница 43: ...Fig 33 Front view with item numbers Fig 34 Bottom view ...
Страница 44: ...44 Fig 35 Top view Fig 36 Left side view ...
Страница 45: ...45 0 0 0 0 1 ji I I MAB225 Fig 37 Scale dri ve n ...
