10
1.4. Description of the block diagram
The frequency of the generator is determined by an HF-oscil lator the ampl i tude of wh ich is e l ectronica l ly
stabil ised. Frequency ranges are selected with push-bu tton MHz. With in the sel ected range the frequency can
be adjusted continuously by control FREQUENCY.
A frequency-modu lator provides vol tage-controll ed frequency m odulation
of
the HF-osci llator
-
e.g. for
wobbulating purposes - in the ranges 75 MHz
. _ .
1 10 MHz, 0.4 MHz ... 0. 5 MHz and 10.3 MHz
.
.. 11.1 MHz
(/\/V'v).
In the amplitude-modulator the ampl i tude of the HF-s ignal can be modulated in a l l frequency ranges and the
HF-signal blanked during fly-back at mode WOB
(/V).
The HF-output stage ampl ifies the power of the HF-s ignal, the amplitude of wh ich is adjustab l e continuously
with attenuator HF AMPLITUDE.
T he output � ignal is ava i lable at connector H F OUT; the output impedance amounts to 7 5 D_
If button CAL. is pressed an X-tal controlled calibration oscillator produces harmonics to ch eck the
ca l i bration of the sca l e. The markers are at a distance of 10 MHz, 1 MHz or 0. 1 MHz, depending on the
sel ected frequency range.
In the m ixer the signa ls of the HF-output stage and of the calibration osc i l lator are m ixed. The low-frequency
s igna l which is obta ined at approx i mately equal frequencies of both signals is ampl ified, l i m ited, rectified and
indicated by a moving co i l meter. If the HF-frequency control is set at a cal ibration frequency, the ind icator,
at exactly equal frequenc ies, indicates a sharp, l i m ited m inimu m between two fu l l sca l es. (Fig.
1).
A 1 kHz-s ine wave signal, produced by a 1 kHz osc i l lator, is used for amplitude- or frequency modu lation
and sel ected by push-buttons AM or FM. The 1 kHz signa: is also available at connector 1 kHz/SWEEP OUT
if button WOB has not been depressed. If bu tton AM EXT. or FM EXT. h as been depressed the H F-signal can
be modulated by an external signal supp l ied to connector LF IN.
If button WOB has been depressed, a saw-tooth signal, produced by
a
saw-tooth generator, is supplied to the
frequency modulator. The sweep of the frequency can be adjusted by potent iometer SWEEP W IDTH. At the
same time the saw-tooth signa l with constant ampl i tude is avai lable at connector 1 kHz/SWEEP OUT.
A square-wave pu lse derived from the saw-tooth signal blanks the output stage d u r ing fl y-back.
The supply section delivers two stabi l ised direct vol tages (-12 V and -18 V) and an a l ternating vol tage for
i llumination of the sca l e.
Summary of Contents for PM5324
Page 1: ...HF Generator 100kHz 110MHz PM5324 9452 053 240 1 9499 450 05511 730801 1 01 ...
Page 15: ...14 Fig 4 Front view Fig 5 Rear view ...
Page 43: ...Fig 33 Front view with item numbers Fig 34 Bottom view ...
Page 44: ...44 Fig 35 Top view Fig 36 Left side view ...
Page 45: ...45 0 0 0 0 1 ji I I MAB225 Fig 37 Scale dri ve n ...
