Service Manuals, User Guides, Schematic Diagrams or docs for : . Rare and Ancient Equipment MFJ MFJ-812 and 810
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INTRODUCTION
The MFJ-810 and MFJ-812 VHF SWR/WATTMETER a r e low l o s s meters p r i m a r y designed f o r 2
meter operation. However i t w i l l f u n c t i o n down t o 2 1 MHz w i t h reduced sensitivity.,,hhe
MFJ-812 a l s o has a f i e l d s t r e n g t h c i r c u i t b u i l t - i n t o m o n i t o r RF r a d i a t e d s i g n a l s .
INSTALLATION
1. Connect a coax c a b l e from t h e t r a n s m i t t e r t o t h e coax connecter on t h e meter marked
" TRANSMT. TTER"
I 2. Connect the antenna cable t o t h e coax connector i n t h e meter marked "ANTENNA".
OPERATION
1. SWR Measurement:
A) S e t t h e FS/SWR b u t t o n t o OUT f o r SWR. (For model MFJ-812 o n l y . )
B) S e t the FWD/REF b u t t o n OUT. Transmit a continuous c a r r i e r and s e t the SWR/
POWER c o n t r o l f o r f u l l s c a l e d e f l e c t i o n .
C) Push I N t h e FWD/REF b u t t o n and read SWR.
NOTE: The SWR s e n s i t i v i t y must be r e s e t when power l e v e l i s changed This w i l l .
m a i n t a i n an accurate SWR reading.
2. Power Measurement:
A) S e t the FS/SWR b u t t o n OUT (For model MFJ-812 o n l y ) .
B) S e t t h e FWD/REF b u t t o n OUT.
C) S e t the SWR/POWER c o n t r o l t o t h e 30 mark. This s c a l e reads a maximum o f
300 w a t t s .
- -- - -- NOTE : T k .
ft i s f a c t o r y --
-
cal i l m t h is control .
However, due t o component t o l e r a n c e when p r e c i s i o n reading i s desi red,
t h e 300 w a t t range can be r e c a l i b r a t e d as f o l l o w s : S e t t h e FWD/REF b u t t o n
OUT. (Set t h e FS/SWR b u t t o n OUT on the MFJ-812.) S e t t h e SWR/POWER c o n t r o l
t o 30, n o t e t h e power l e v e l on t h e 30 w a t t scale, then r o t a t e the c o n t r o l
t o read t h e same power l e v e l on the 300 w a t t sca'?. Mark t h e c o n t r o l s e t t i n g
f o r t h e r e c a l i b r a t e d 300 w a t t range.
FIELD STRENGTH METER (For MFJ-812 Only)
1. Connect a 1 t o 2 f e e t l e n g t h of w i r e t o the b i n d i n g p o s t on t h e r e a r o f the meter.
2. Set t h e FS/SWR b u t t o n t o FS ( I N ) . The FW@/REF b u t t o n can be e i t h e r I N o r OUT.
3. A d j u s t the SWWPCWER c o n t r o l f o r the d e s i r e d meter s e n s i t i v i t y .
TRANSMITTER ANTENNA
5 0 OHM STRIPLINE
- --- -
ON M F J - 8 1 2
''IUF
ONLY
1
1 UF FIELD
OUT I I s w 2 STRENGTH
f ANTENNA
REF
1 0 0 uA sw1 1N 3 4
--
ON MFJ-810 JUMPER A TO B L - - -- -_I
MFJ-8 1 2 / 8 1 0 SCHEMATIC DIAGRAM
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