Sencore FC51 User Manual
FC51
1GHz Frequency Counter
Operation, Application and Maintenance Manual
SIM PL IFI ED O PE R A T IO N S
Refer to Table of Contents for location of complete information.
Corresponding
to Selected Input
Push Button
Lfor Desired Read Rate
o p\q q q q q q
I \ | \l. I I I I I · >»
SE NC O^EX 1GH z : F R E QU E N C Y COU N T E H
50 Ohm I 1 Meg
Dummy Load input for
for high frequency circuit testing
testing
i
Rea d Frequency
Directly from Display
Push Button
Corresponding to
input Frequency
SIGNAL CONNECTION SELECTOR G U ID E
FREQUENCY RANGE
SIGNAL SOURCE
Audio Circuits
Digital Pulses
Digital Square Wave Signals
High Voltage Signals y
IF Stages y
RF Oscillators (transmit or receive)
RF Signal Generators
Signal Tracing
Transmitter Outputs
10 Hz -10 0 SVIHx 10 MHz - 1 GHz
1 a
Direct
/
/
y y
1EG
Isolated
y
y
50
Direct Isolated
y (ecu
y <ECL)
Pick-up
Loop
Γ /
i y
■WARNINGS-----------------------------------------------------------------------------------------
1. Always r e place fuses wi t h correct value, i mprop er fus e(s ) voids wa r r anty .
2. Refe r t o specif i c atio n s f or m aximum 1 Meg inpu t a n d 5 0 Ohm i np ut voltage.
10 Hz-1 GHz
Antenna
y
y
y
INTRODUCTION
DESCRIPTION
Most ele c t r onic s techn icians are fin ding more and m o re
need for a high accuracy digi ta l fr eq ue ncy count er.
Co mm uni cati ons shops a nd commer cial broad cast s t a
tio ns need bo th a wide f r equency ran ge a nd high ac
cur acy in t he i r fr e q uency counte rs to meet t he FCC
requ i reme nts for accu r a te measu reme nts of various
tr ansmitter freq ue ncies. Service t echn i cia ns f i nd that
a freq uency cou nte r is a valu a b le piece of test e qui p
m ent for troubleshooti ng t he digi tal ci r cuits found in
UHF a n d VHF television tuner s and th e mode rn digi
tal FM receivers. Other appli c atio ns (like video tape
re corder, medical equ ipment, and industri al m ainte n
anc e ) requ i r e fr e quen cy cou nte rs fo r man y test s an d
adjustments.
The FC51 offers both a wid e input freq uen cy range
and high acc uracy for work in any of thes e a pplicati o ns
whe r e the signal is betw e en 10 Hz and 100 0 MHz.
E xtra fe atur es, like all push button op eration and a uto
matic sele ction of prescalers , are n ormally foun d onl y
on fr equen cy cou n t ers costin g much m or e t han the
FC 51. A review of the follow i ng s ection will cover
the se speci al feat u r e s and exp l ain h ow they simplify
the o perat ion of the FC51 and offer ve rsa tility no t
usu ally found in a fre quency c oun ter in this price
range.
FEATURES
The F C 51 1 GHz Fre quenc y Cou nte r allows dire ct
readi ngs of all fr e q u e n c i es from 10 Hz thr ough 1 GHz
wi t h accurac ie s that e x c eed the FCC speci f i c a tion s
for all communica t i ons work u p t o 1 GH z . The meta l
case of the F C 51, along with in ter nal RF shielding,
pro v i des interf erence-fr ee measu r em ents in p ractical
ly any ty pe of R F field.
The large (. 5” ) 8-digit display allows dire ct readings
wi th automat ic placeme nt of the d eci mal . Special
in di ca to r lights sh ow whether t he co unte r is mea s u r
ing LiH z' \ or “MHz”, and an o v e r f low in di ca to r in
dicates that a re adi ng re quir e s m ore than the full 8
digits o f readout .
The FC51 feature s large, comfort-size d pus hb utt on s
fo r ease of o peratio n. These butto ns select the de
sired inpu t jack, read r ate , a nd frequency range. Three
in puts are available. The first is a fuse -protecte d 50
Oh m ter mi na tion for prope r r eadin g of high frequ en
cy signals. The 50 Ohm t ermi na tio n prevent s cable
ring i n g which coul d cause inacc ura t e r eadin gs.
The second inp ut is a high sensitivity inp ut with 1 Meg
oh m loading to allow di rec t conn ect i ons t o lo wer fr e
qu en cy cir c u it s. This i npu t is c on trolled by a fro nt-
panel sensit i v it y control wh ic h allows ma ny noisy sig
nals to be measure d which nor mal ly will pro duc e er
rat ic readin g s o n a high sen s iti v ity counter.
The sensit i v ities of b ot h of th ese inputs have bee n de
signed f or fa s t signal tracin g in most a pplic a t ions. If
ad dit i onal sens i t i vity is required for special ap plica
tions, th e optio na l WBA52 1 MHz throu g h 1 GHz
Wide b a n d A mpl i fier prov id es an add i ti onal 30 dB of
in pu t gain. The WBA52 is power ed fr om t he acce s
sory j ack on t he fr ont o f th e FC51.
The th ird input is S enc ore’s exclusive crys tal c heck
whic h allow s an y c r y stal to be te s t ed by sim p l y in
ser t i ng it int o the spe cial front pan e l tes t so c k e t.
Two read r ates give a choice of fast upd a tes o r maxi
mum r esoluti on , depending on th e typ e of signal you
want to meas ure . Four d i f ferent freq uency range but
to ns prov i de th e be st r eso l utio n for a n y measurement.
Two bui lt-i n pr es ca le rs extend bot h the high and low
fre quency capabili t i e s of the FC51. The fir st pr e
scaler allo ws frequenci es f r o m 100 MHz to 1 G Hz to
be mea sured and t he seco n d “audio pres c aler” pro
vides ad ditional dig its of resolu t i on when m easur i ng
fre que ncies bel ow 20 KHz. Bo th prescal ed op tion s
provide automatic decimal placem ent for direct read
ings.
The high acc ura cy timeb a s e oscilla t o r is built i nto a
prop or t iona l ly-con t rolle d oven to assure the hi ghe s t
accuracy pos s i b le over a wide range of ambi ent tem
peratures. The en tire oven an d osc il la t o r is c onta ined
in a single plug-i n mo d ule to allow the opt i on of e x
chang i n g the mo dul e wit h one that is freshly cal i brate d
so tha t i t is not nece ssa ry to return the en t i r e coun ter
fo r acc uracy cal i bra t ion .
Fina l l y, the FC5 1 o ff ers a choice of 1 10-120 VAC
line ope ra tion o r 12 VDC op era tio n for versa t i l i t y of
use in bench or port able testing . Input conn ect i ons
are mad e wit h the supplie d coun t er p ro b e , pickup
loop or a djustable anten na.
SPECIF ICATIONS
INPUTS:
Fre qu ency Range
1 Meg o h m I np ut
10 Hz — 100 MHz
50 Ohm Input
10 MHz - 1 0 0 0 MHz
50 Ohm VSWR: Lowe r t han 2.5:1 thr ough
1 GHz
CRY STAL CHEC K
1 — 20 MHz Fun damental Frequency
(Overt one crystals read at approxi mat ely funda
men tal frequency.)
ACCUR AC Y
i Ti meb a se a cc u r ac y i 1 digit
TIMEBAS E (repla c e a b l e module)
Crystal Fre quen cy: 10 MH z —p ro portion al oven-
controlled
Set a bility: — 0.01 ppm (.00 000 1%)
Tem per ature Stabilit y : 0 . 5 ppm (.00 0 0 5%),
0—40to C. Am bie nt after 10 minute wa rm up
Maxim u m aging: 2 ppm/ye ar
Timeb as e out put ava ilable th ro ugh rear panel
BNC jack .
Re commend ed re cali bration interval: 1 year for
FCC tolerances b e l o w 8 00 MHz, 6 mont hs f o r
frequencies above 80 0 MHz.
MAXIMUM RES OLUTI O N
10 - 5 0 0 Hz
.01 Hz
500 - 200 00 Hz
.1 Hz
20 KHz - 10 0 MHz
1 Hz
100 - 1 000 MHz
10 Hz
READ RAT E S (gate times)
1 se c ond or .1 second
Pus hbutton selected .
INP UT PROT ECT I ON
1 M egohm Input
250 V pp to 10 KHz
50 V pp to 3 0 MHz
8 V p p t o 10 0 MHz
50 Oh m Input
5 Vo l t s RF, fuse - prot ecte d
100 Vol t s DC ma x.
GE NERAL
DISP L A Y: 8 digit, 0. 5” LED, auto deci mal,
overf low, “ Hz” a nd “MHz ” indicat ors .
SIZE: 5. 5” x 7. 83” x 9 ” HWD (14 cm x 19.9
v· O O Ο
WEIGH T : 6.5 lbs. (2.9 Kg)
POWER: 10 5—130 VAC, 50/60 Hz, 45 W m ax.
(220 VAC co n versio n available) 12 VDC, 2.2
Amps maxi mum
FUSE RE QUIREM ENT S : 1/ 8 Amp RF fuse fo r
50 Ohm input, 2 spare fuses includ e d on P.C.
board. 3 Amp, 3AG Fa s t blow for 12 VD C leads.
One sp are fuse inc luded .
AC LI NE: Transforme r int e r nall y fused.
ACCE S S O R Y O U T P U T VOLTAGE : 9 -12 VDC
th roug h th e front panel jack to pow e r WBA52
1 GHz Amplif ier.
SEN SITI V I TY
1 Megohm Input
10 mV typical t o 20 MHz
25 m V average when sens it i v it y control is at
max i mu m — c on t inuousl y v a r ia ble to cut- off
(See respon s e curv e. )
50 O hm I npu t
100 mV average
3 mV average wi t h WBA52
(See res p onse curv e. )
ACCE S SORIES
Supplied: 39G112 Direct/i sola t ed C ounte r Prob e
39G11 1 Fused DC Supply Lead
39G1 38 RF Pick-up Loo p a nd exten
sion
AN 210 Antenna
Optio nal: WBA52 1 GHz Wideband Amp l i fier
Spec i ficat i o ns subje ct to change without no tice.
GRA P H 1 — Guaranteed and typical sensitivity curves f o r FC51.
F R E QU E N C Y IN MH z Frequency Ranges
CONTROLS
LED read ou t , 8-digit wi th au to matic pla cemen t
of d e c i mal f o r all read in gs.
Overflo w ind i c a tor, which sho w s wh en reading
excee ds 99. 9999 99 or 999.99999 MHz.
Vinyl- c l a d steel case, provides full RF shielding
for stabl e readings.
INPU T SELECTOR BUTTON S
Crysta l check inp ut button for te sting crystals
ins erte d i nto soc ket (15).
1 Me g ohm inp ut but ton selects high sensitivity
input jack (14) for me a s urin g f req uenci es up to
100 MHz.
50 Ohm inp ut but ton sele cts high fr equency in
put ja ck (1 1) for p roper te rminati on of higher
inpu t signals. Op e ratin g r a nge 10 MHz—1 GHz,
H and l e/ t ilt stand for po rtable a pp l ication s or for
tilt ing un it on be n c h .
Powe r s w it ch, contro l s unit wh e n ope rate d fr o m
AC or DC inpu t s.
500 Hz—20 KHz range button provides in ter nal
Φ
re so l ution m ult i pli er t o p roduce .1 Hz resolut i on
with a 1 sec on d re a d rat e . Used only with 1 Meg
ohm i nput jack (14 ).
20 KHz —100 MHz ran ge button provides a d i re ct
Φ
(non -pre scal ed) in put for dir ect c ounting t o 1 00
MHz. Wo rk s wit h eit her in put ja c k (11 or 14).
100 MHz—1 GHz range button provides a 10: 1
φ
prescal ed input with automa tic decimal pla ce
me nt. Should be used o n ly with 50 O hm input
jac k (1 1 ).
MHz range li ght use d with aut om atic dec i mal for
direc t readout of frequen c y .
Hz range ligh t used with automat i c d ecimal for
φ
direc t readout of fre quen c y.
REAR PANEL
Timebas e output jac k provides a buf fere d output
/-if fJho 1Π MH7 rpfprAtirp ns Hllat nr fnv* nhw k infr
of the 10 MHz re f eren c e oscilla t o r f or c hecking
Θ
acc urac y wit h another f r e que ncy standard or for
cali brat i n g other less acc urat e coun t ers.
10 Volt accessory ja ck for po we rin g WBA52
1 GHz Wideban d Ampli f ier or o ther accessories.
Ground return is through shield of input jack .
50 Ohm i np ut jack prov id e s prope r termina tio n
for 50 Ohm coa x i a l cable to preven t doub le
co untin g d u e to r e f l ections. RF prot ecti on fuse
is loca ted inside un i t al ong with t wo spar e fuses.
REA D RAT E BUTTONS
.1 se c ond read rate provides appro ximate ly 1 0
readi n g s pe r second for fast updates whe n maxi
mum re s olu tio n is no t necessary.
1 seco n d read ra te provid es approx imately 1 read
ing per second fo r o n e e xt ra di git of resol utio n
and for more st a b l e readin g of “drift y” signals*
Sen s i t i vity adjus t cont rol op erates in conju nction
wi th 1 Megohm inp ut jack (14) to provid e variable
sen s i t i vity for meas u ring signals with n oi s e in
fo rm ati on .
1 Megohm i np ut jack pro v id e s high sensitivity
fo r dire ct signal c onn ections .
Cry stal check s ock et pr o v ides unive rsal sock e t
@ @ @00 © ΟΦΟ Θ Ο 9 φ φ θ
for t estin g crys tal s out of ci rc uit.
Antenna clips f or sto ri n g AN210 ant enn a.
Φ
Spare fuse clip for storing a spare 3 A m p fus e for
Φ
use in the DC supply leads.
AC input lin e cord .
DC i nput j ac k f or supplying 12 VDC ( negative
gro und ) for portable oper ation of counter.
Cord wr apper s for s to r in g AC line co r d a nd test
©
leads.
SUPPLI E D ACC ES S OR IE S
3 AN210 Adjust able Ante nna for picking up off-
the- a i r signals.
39G1 12 C oun te r Probe w ith direct / i solate swi t c h
for use when direct con nection is d es ir ed.
39G1 11 Fused DC Supply Leads fo r po wer i ng
FC51 fro m au to accessory j ack.
39 G138 RF Pick-up Loop for mak ing hig h fre
quenc y or hig h pow er frequ e ncy me asurem ents
whe n a direct c on nection is not des ire d.
OPTIONAL AC CESSORY
FRE QUE NCY RANGE BUT T O NS
10 Hz—5 00 Hz range but ton provide s inter nal
Φ
resolutio n mul ti p l ier to pr oduce .01 Hz resolu
tion wit h a 1 second read rate . Used only w it h
1 Meg ohm inp ut ja c k (14 ).
WBA52 1 GHz Wideband Amplifie r to increase
©
input sensi t i vity of e i t her 50 Ohm or 1 M ego hm
inputs for m e as u r i n g e x t r emel y small signals.
Power e d fro m 10 V o lt accessory jack (,9) on
FC51.
6
ο ο σ ο
I. I ι ι
REAR VIEW
------
ACCESS OR IE S
Fig. 1—Location of controls ana features.
O PE R AT IO N
INTRODUCTION
Befo r e using your FC51 for the firs t t i me , ta ke a few
mi nut es to read th rough the opera tio ns and app l ic a
tions sectio n of the manu a l c arefu l ly to acquai nt your
self wi t h the fe at u r e s of the FC51 . On c e you are f a m
iliar with the general op erat i ons, most t es ts can be per
fo rm ed with the info r ma t i on provide d on t he FC51’s
front panel .
POWER CONNECTIONS
AC OP ERATION: The FC51 is de s igned to b e oper
at ed f r o m 105 -130 VAC (50/60 Hz). If 210-230 VAC
opera tion is requir ed, the unit may be mo dif i ed (at
ad dit ional cost) by th e Sen core Service D epart ment ,
3200 Sencore Drive, S io u x Falls, SD 57 10 7.
To op erate t he FC51 from a st andard AC lin e:
1. C onn e ct the AC c ord to a 117 VAC (or 2 20
VAC fo r m odified u nits) ou tle t.
2. Turn the power s witch on.
3. The FC51 is i mm e diat e l y ready for frequency
me a sureme n ts. If very pre c i s e me asure me nts are
to be m a d e , the un i t sh ould be all owe d to oper
ate fo r at lea s t t en min utes to allow the tempe r
ature of the cr y s ta l oven to s ta bil iz e.
DC OP ERATION: T h e FC51 m ay be oper ated from
a 12 VDC power source cap a b le of d el iv ering 2. 2 Am p
eres. Po w e r is s u p p lied throu gh th e stand ar d ada pter
jack locate d at th e bottom of th e rear panel . A set of
fus ed DC sup ply leads is supplied with the FC 51 for
DC o per ation. Make sure the pr op er size fuse (see
FUS E RE P LACEMEN T b elow) is in the in-l in e fuse
hol der for prote cti on of yo ur FC51 duri ng DC o p er
ati on.
-----------------------CAUT ION-----------------------------
Observe proper p o la ri ti es (negat ive gr o und) when
connect i ng t he DC p o w e r source. No dama g e
will result if the polarity is reversed, but t he FC51
will not operate wit h a reversed pol a ri ty.
To oper ate the FC51 from 12 Volts DC:
1. Co nne ct the adapt er plug of the supplied
39G11 1 DC p ow er sup ply leads to the DC input
jac k on the back of the FC5 1.
2. Co nne ct t he sta nda rd a utomot i ve a c cesso r y
plug o f the supp l i e d power supply leads to the
sour c e of 1 2 VDC, observing p r oper polarity.
3. Turn th e po wer switc h on.
4. The FC51 is im medi ately ready for f requ ency
measure ments. If very precise me a s ure men t s are
to be m ade, th e un it sho u ld b e al low ed t o op erat e
for at le ast ten min u tes to allow the temperature
of the cry sta l o ve n to stab ilize .
_______
FU SE REPL ACEMENT
---------------------------
Always rep l ace the fuses wit h t he value sp ecif i e d.
Larger val u e fuses may cause in t ernal damage t o
the FC51 o r cause a fire haza r d and will void all
war r anti e s.
If th e FC51 s hould fail t o op era t e when c onn ected t o
a 12 V o lt DC p ow er sou r ce , check the, powe r su pply
fuse. If the fuse continues to b low each time it is r e
plac e d , refer to the service and mai ntenan c e secti on
of the m anual.
AC FUSE: The FC 51 does not require an AC fuse as
th e transformer uses a special in ternall y protected pri
mar y winding.
WARNING
--------------------------
Fig. 2—Connecting the 12 Volt DC supply lead. Be sure
to observe proper polarity (negative ground).
DC FUSE: Th e fu s e f or DC operation is loc ated i n t he
in-line fus e holde r in the 39G111 power supply leads.
Di sconnect the power su p p ly leads fro m t he DC sup
ply before r e movi n g the fuse. The fuse hold er is
open ed by pushing slightly ag ai n st th e t wo sections
of the fus e holder and tw istin g t he two sect ions in
opposi t e d i rec t i ons.
Replac e th e fuse with a 3 Amp Fastblow 3AG fuse
only.
50 OHM INP UT F U S E: The 50 Ohm input is prote ct
ed b y a special R F fuse loca ted inside th e b ot tom
cover o n t he inp ut PC board of t he FC51. F a i l ure of
th e FC51 to stab i li z e an d a lack of sensitiv ity th r ou gh
the 50 Ohm in put ind i c ates possi ble failure of the 50
Ohm inp ut fuse .
3
Fig. 5—The fuse in the 39G111 DC supp ly lead is
changed by separating the two halves of the fuse holder.
The pr ocedu res for checking this fu se ar e as f o llows:
1. Connec t one end of the su p plied co nne ct or
cable wit h a BNC co nn ector on each e nd to the
10 MHz refe r ence output j ack located on the
ba ck of the FC 51 . C onne ct th e other e nd o f the
cable to t he 50 Ohm inp ut ja c k .
2. Depress the 50 OHM INPU T bu tton a nd the
20 KHz to 100 MHz F R E Q UENCY RANGE
button .
3. The coun ter should re gister 10.00000 MHz
1 count wh en the 1 SEC READ RATE button
is depre ssed. Failu r e to obt ain a c o r re c t reading
ind i c a t es f use failu r e . For fuse replace me nt in
structions, re fer to th e ma i ntenan c e section o f
thi s m anual.
TABLE 1 - BLOWN FUSE CONDITIONS
FUSE
DC Power
50 Ohm
input
TYPE
3 Amp 3AG Type
1/8 Amp iVlicro-
fuse
CONDITIONS
Unit will not turn on
when DC-operated.
loss of sensitivity at the
50 Ohm input. Unstable
readings in 20 KHz-
100 MHz and 100 MHz-
1 GHz frequency ranges.
Fig. 5—Access to the
50 Ohm inp u t fuse is
obtained by removing
the bo tt o m panel. Two
spare fuses are supplied
Be sure to disconne ct
the AC p o w e r cord be
fore removing the b o t
tom p a ne l
Fig. 4—Th e l O MH z ou tpu t (back panel) provides a con
venient signal source for testing the 50 Ohm in p u t fuse.
The cou nt er should read 10 MHz with good stability.
SIGNAL CONNECTION S
Several metho ds may be used for m e asuring fr equen
cies w i t h the FC 5 1 . In ma ny cases a dire ct conn ec tion
to th e circu it under test is desir e d . The 39G1 12 Fre
qu en cy Co un t er Probe, su pplied with the F C51, al
lows a dire ct or capa ci ti vel y iso lated co nnect i on. Othe r
te sti ng te chniques re quir e i ndi rec t or “l oose” coup
ling to p r event the cou nt er ’s in pu t circuits fro m dis
tu rb in g the circuit being m easured—the 39G1 38 R F
Pick -u p Loo p or the AN2 1 0 A nte nna ar e intend ed to
be used for th i s ap plica tion .
USING THE SUPPLIED
COUNTER PROBE
Th e supplied 39G112 Fr equen cy Cou nter Pr o be al
lows a direc t or capacitively is olate d inp ut. T he ch o i c e
o f th ese two inputs is made with a miniat ure slide
switch built into the probe. The Freq ue ncy Counte r
Probe may be used w it h the 1 MEG INPUT or th e
50 OHM IN PU T.
Fig. 6—S upplie d 39G112 Counter Probe is equ ipped
with a switch to select direct or isolated connections.
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