Document
VALVES
LOW NOISE
VHF TRIODE
A2599
ISSUE 2
The A2599 is a low noise v.h.f. triode for grounded-cathode use. It is a commercial version of the CV5242.
BASE CONNECTIONS h
h
k k g
AND VALVE DIMENSIONS
k Base: B9A
k Bulb: Tubular. Max. overall length:
g Max. seated length: Max. diameter:
a
56mm. 49mm. 22·2mm.
Viewed from underside of base.
HEATER
6·3 0·3 (approx)
V A
MAXIMUM RATINGS (Absolute)
Va pa
Ik
+Vs
Vh-k(pk) Tbulb
250 2·5 20
20 100 200
CAPACITANCES (Measured on a cold screened valve)
Cg-all. less a: 3·5pF;
Ca-all. less g: 0'7pF;
V W rnA V V °C
Cg-a: 1·lpF.
CHARACTERISTICS
Va i,
Vg
gm
[.1
*Cin(w) *nn(w)
130 16 -1 (approx) 15 60 6 (approx) 30 (approx)
* Measured hot at 45Mc/s with anode decoupled to cathode.
V rnA
V mA/V
pF kfl
-.,------T-H-E---M--O--V-A--L-V-E-C--O-.-L-T-D-.-. --B-R-O-O-K--G--R-E-E-N-'--L-O-N--D-O-N-'---W--.6--AUGUST 1962
A2599
TYPICAL OPERATION Class A. Low Noise Amplifier. Grounded Cathode Connection.
Used in the first stage of a cascode amplifier, followed by an A2521 triode, operated in grounded-grid connection, as shown in figs. I, 2 and 3.
Va(b)
180
Ra 3·3
Rk 68
[a 15·5
Frequency
45
*Noise factor (average)
1·5
tNoise factor (average)
1·3
:!:Power gain (approx)
30
Optimum source resistance
(approx)
1300
*Input circuit tuned.
+Input circuit adjusted for lowest noise factor.
tFor the cascode amplifier.
250
68 14·5 200 6·8 4·7 20
290
V
kn
o
rnA Mcjs
dB dB dB
n
INSTALLATION
The valve may be mounted in any position. The use of a retaining device is recommended.
If a screening can is used it should be blackened inside and out. Free air circulation around the bulb or the outside of the screening can should be provided.
Provision of circuit information in this publication does not imply a right to use any invention which may be involved and which is the subject of patents by whomsoever owned.
2
A2599
R2
Fig. 1.
Circuit of 45Mc/s cascode amplifier.
COMPONENT VALUES FOR FIG. I.
Valves
VI A2599 V2 A2521 V3 Z77
Capacitors CI C2 to C14, C 16 CI5
2-8pF l000pF 470pF
Resistors
RI, R3 R2, R4, R8 R5
R6 R7 R9 RIO
6811 3·3k11 4'7kO
0·25W IW 0'25W
l'OM11 1500 22k11 10011
0·25W 0·25W 0·25W 0'25W
Inductances
All coils of enamelled copper wire wound on ! in. dia. former.
Ll L2,L6, L7 *L3 *L4 *L5 *L8
Turns 9 80 12 35 10 12
*Core is of the type recommended for use up to 100 Mc/s,
s.w.g. 18 34 20 30 20 20
3
A2599
Inp,Jt stuo s
," ,I I
R2 R3 (8
Fig. 2.
Circuit of 200Mc/s cascade amplifier.
ht +
COMPONENT VALUES FOR FIGS. 2 AND 3
Resistors RI R2-R3 R4
Inductances LI
L2 to L6
L7
6811.
rooi o,
I kll.
Capacitors
Cl, C6 C2, C4, C9 C3, C7, CIO C5, C8
3-30pF ceramic trimmer. 4700pF feedthrough. lOOOpF. 2000pF.
It turns 14 s.w.g. copper wire tin. i.d. tapped at 1 turn from earthy end.
20!in. of 26 s.w.g. enamelled copper wire close-wound -i\rin. i.d. air-cored coil. H turns 14 s.w.g. copper wire tin. i.d. tapped at t turn from earthy end.
4
A2599
Input socket
C3/;,3in.
32 ~1
L2
C2 A2599
A 2521
Output socket
Fig. 3.
Layout of 200Mc/s cascode amplifier.
5
A2599
b
II
i
I
J
/
V
I/
/
I
!i
[L'tmeasured)
II
II
~ I I ]I zo 2 I
l/
!V
: ./
1110
a
10
Fig. 4.
50 100 (Mel.)
500
Variation in average minimum noise factor against frequency for A2599-A2521 cascode amplifiers. (FI measured using a noise diode).
1000
6
A2599
20 I
~:::..
1702
Cl
I
" :::..
:::"~I
Cl
...:.
,
I
15 :::..
V) p
Ij_
~
-';"'0",<. , l'. Si1/
; Cl t~
-;Vj ;..
~ ~I
f-I~ ~
';>.t
~'i
,.;,'0/
/
~~
..;..<:::'1
5 /~
!50 100 150 200 250
Fig 5.
7
A2599
~17~O~l~:~IJ=CIJ[=r~rT~Tl-r~rT-rTl-'''rT,-,,-r~I~,~~----20
1£
[I
[
1/
II
4 3 2 -I Vg (V)
Fig. 6.
RIIOI Printed in England - K-C.
.