NATIONAL RADIO ASTRONOMY OBSERVATORY Green Bank, … · Vn. Thermal Calibration The thermal calibration was by inserting a directional ooupler and an argon noise source into the systems

NATIONAL RADIO ASTRONOMY OBSERVATORY Green Bank, West Virginia

Electronics Division Internal Report No. 26

750 MC-1400 MC RECEIVERS AT THE 300-FOOT TELESCOPE

Dewey Ross November 1963

NUMBER OF COPIES: 100

750 MC-1400 MC RECEIVERS AT THE 300-FOOT TELESCOPE

Dewey Ross

General

This report covers lab tests made on the 750 Mc and the 1410 Mc systems

which were installed on the 300-foot telescope on October 15, 1963.

I. Antenna

The Jasik Model 275, SN No. 3, 750 Mc-1400 Mc feed was modified to utilize

the Poor Man* s Calibration System.

VSWR measurements were made before and after the calibration system was

added, with and without the radome. The results are shown in Figures 1, 5, 6, 15,

and 16.

H. Sky Horn

On October 22, two sky-horn assemblies (ASI L-band horn, 20° E-plane bend

(NRAO), a FXR waveguide to coax transition, 7 1/2 feet of RG-9 coaxial cable, and

a RF Products 48 VDC coaxial relay) were installed on the 1410 Mc system.

Two systems, one looking east and one west of the apex, were used to elimi¬

nate the possibility of interference from the sun.

VSWR measurements are shown in Figures 11, 12, 13, and 14.

HI. 750 Mc Front End

The 750 Mc system consists of an AEL coaxial switch and the Gordon Stanley

mixer with a ceramic tube amplifier (see Internal Report No. 8, "Ceramic Tube -

Low Noise Front Ends", by Joe Carter).

The system noise temperature is 410 0K with a crystal current of 0.7 mA.

The band pass is shown in Figure 2, A block diagram is shown in Figure 21.

- 2 -

IV. 1410 Mc Front End

The 1410 Mc system consists of an AEL coaxial switch, the Microwave Physics

Model No. MPC 10244 parametric amplifier, and a LEL Model LAC-3 mixer-

preamplifier.

Test results of the parametric amplifier are covered in Internal Report No. 25,

"Microwave Physics Corporation L-Band Parametric Amplifier", by B. Pastemack

and B. Hansson.

However, at the time of installation the band pass was 30 Mc (see Figure 7),

the gain was 17 db, and the noise temperature including the input cable and coaxial

switch was 180 0K.

The LEL mixer-preamplifier had a 7 Mc band pass (Figure 8), 39 db gain, and

a noise temperature of 1590° (DSB) with a crystal current of 0. 6 mA.

A block diagram is shown in Figure 22.

V. Overall System

Band pass measurements of the entire systems were made and the results are

shown in Figures 3 and 4 for 750 Mc and Figures 9 and 10 for the 1410 Mc system.

The detector linearity was measured. A block diagram of the measurement

set-up is shown in Figure 23, and the results are shown in Figure 17 (750 Mc) and

Figure 18 (1410 Mc).

VI. Calibration System

Both the 750 Mc and 1410 Mc systems utilize the Poor Man's Calibration (to be

covered in more detail in "Poor Man's Calibration System", not yet published) in which

three NE 51' s are used to supply the calibration signal.

750 Mc — Two NE 51' s are mounted on the ground plane, level with and mid¬

way between the dipoles, one on each side of the H-plane of the 1410 Mc horn.

1410 Mc — One NE 51 is mounted through the back of the horn and is positioned

in the center of the E- and H-planes of the horn.

A drawing is shown in Figure 24.

- 3 -

Vn. Thermal Calibration

The thermal calibration was by inserting a directional ooupler and an argon

noise source into the systems. (A block diagram is shown in Figure 25.) The an¬

tenna was replaced with a 50 ohm load which had a VSWR equal to that of the antenna.

The argon source was calibrated against known thermal temperature. The load was

then replaced with the antenna and the neon (NE 51) calibrated against the argon source.

The directional coupler and argon source were removed and the insertion loss

measured. The power ratio of this loss was used as a correction factor to determine

the true calibration signal.

The correction factor for the 750 Mc system is the power ratio of . 13 db and

. 10 db for the 1410 Mc system.

Figure 19 shows the 750 Mc thermal calibration and Figure 20 shows the 1410

Mc calibration.

The corrected calibration signal for 750 Mc is 16.25 0K and for 1410 Mc is

12.0 TC.

Vm. Cabling

The cabling used for the front ends is basically the same as the schematics

shown in Internal Report No. 5, "750 Mc and 1400 Mc Receiver Front Ends at the

300-Foot Telescope", by Hansson and Ross.

Connections will be listed here, but a schematic is not available at this time.

Cable Type Pin No. Purpose

P3 Styroflex 1400 Mc IF



P10 18 conductor shielded A Shield (switch drive common)

B Spare (BNC at focal point)

C Spare

-4 -

Cable

P10 (continued)

Type Pin No. Purpose

Pll 18 conductor shielded

E Switch drive No. 2 (1400 Mc)

G Spare

H Spare

J Switch drive No. 1 (750 Mc)

K Switch drive No. 2 (750 Mc)

L 750 Mc motor control

M 750 Mc motor control

N Spare (BNC at focal point)

P Spare (BNC at focal point)

Q Spare (BNC at focal point)

R Spare (BNC at focal point)

S 750 Mc motor control common

T Spare (BNC at focal point)

U Spare

V Spare

A Shield (crystal current common)

C Spare

D Crystal current 1 (1400 Mc)

E Crystal current 2 (1400 Mc)

G Thermistor-air temperature

H Spare

J Crystal current 1 (750 Mc)

K Crystal current 2 (750 Mc)

L Calibration voltage (1400 Mc)

M Calibration voltage (750 Mc)

P Thermistor-load-eommon

Q Thermistor -load

- 5 -

Cable

Pll (continued)

Type Pin No.

P13 4 conductor shielded



Purpose

s Calibration voltage - 750 Mc

T Sky horn - 48 VDC coax relay common

U Calibration -common

V Thermistor-air temperature-common

A Reg AC 750 Mc-1400 Mc

B Reg AC 750 Mc-1400 Mc

C Remote sensing - 750 Mc-1400 Mc

E Shield to ground

F Remote sensing - 750 Mc-1400 Mc

C Noise tube coil

E Shield ground

F Noise tube relay

A Reflector parametric amplifier

B Beam

C Cathode

Jn

Figure 1 750 Mc — after calibration system was added and with radome on.

iniii

Figure 2 750 Mc — mixer-preamplifier; 720-725. 5 Mc.

■■■■■■■■■

Figure 3 750 Mc — entire system (front end and back end), switch locked in signal; gain modulator locked in signal; bandpass 720 Mc to 726 Mc, centered on 723 Mc.

■MMSMMMM m^f gyu MW pj^gM^g ]|JJJHM£!^SM mil mn

■—■■—Ml mmuH Figure 4 750 Mc — entire system (front end and back end), switch locked in

signal; gain modulator locked in comparison; bandpass 720 Mc to 725. 5 Mc, centered on 722. 5 Mc.

Figure 5 1400 Mc — after calibration system was added without radome.

Figure 6 1400 Mc — after calibration system was added and with radome on.

Js"_ '- - Win ftMF*"a V^^^Fa ff^WBs

Figure 7 1400 Mc — input cable, switch, parametric ampHfier and output cable. Switch locked in signal.

Figure 8 1400 Mc — input cable, switch, parametric amplifier, output cable and LEL mixer-preamplifier. Switch locked in signal; bandpass 1416 Mc-1423 Mc, centered on 1420 Mc.

I mm ■■■■■—■■■ Figure 9 1400 Mc — entire system (front end and back end), switch locked

in signal; gain modulator locked in signal; bandpass 1416 Mc to 1423 Mc, centered on 1420 Mc.

WMBOtm ■Mi muQ

Figure 10 1400 Mc — entire system (front end and back end), switch locked in signal; gain modulator locked in comparison; bandpass 1416 Mc to 1423 Mc; centered on 1420 Mc.

Figure 11 Horn No. 1 with standard transitron.

Figure 12 Horn No. 1 with modified transitron.

Figure 13 Horn No. 1 with bend and modified transitron.

Figure 14 Horn No. 2 with bend and modified transitron.

""— - BVItflTT flOHl*

1.15 X.IO ^ , --^ *>. v

1— "a* ^ 1.14 , _ __ ^

• L 3 7

c 1" 5 1.13 - -nr- t -<»- S. - X ; / ̂ ^ _ ^^^r - -

-• \ - ^ î.^ ,^? S^ v _ .,._ ^ t. Z ^^^ ^ S^ > 2 ^ ^ / ^K ^ ^«r A - - 1.12 , ^ J.- - _ _ , _ -^ _^_ _ *C _ . _ _ __, _ ±.±4 ^ - - -^ -^_

^ ^ ^ u S v V v S S^ C y 5 y Z ^ i 11 .- 2 ^ 4 2 5 .t

\ ^ -L ^ Z i Z 2 r- - 3 ■V » L- J. _J t S r

T 1A ^ :_ _ _>^l .t- ^^- __ _ ______ _ __ _i_ 3- __ _ _ 1.10' ---,|-_ j^.-^.------^-- _ _^_ __ _ ,.

^«- - £ \ v ^ ^ > z: S ~~ 1 no X 5 3

\ ^ 3 \ >^ t -"i

^ v? r I.O84 - -, L _ _ _ 3 i.uo- ^ - --£- \ ^ t ^

\ 7 -1

3 t V 1 07, - X 7 3 1. U f ' -^ f

v_

^ 7 3 \ / -1 — — —

^ 7 I infi— A- - - -,L_ _ _ _ __ _ .3.

1.05 -

■\ (\A. - _ _

-

700 710 720 730 740 750 760 770

Figure 15 Jasik Feed, Model No. 275, SN 3 (before calibration was added).

780 790

____ | ____ _ _ _- . '--- cjjfiaii. HUQI: UUSIUC

on _ _ _ _ ■ , r

19 _ 2" : t

.18 _ —-j- L

1 . 17 ^ T

1- r

16 L- _ _ z _ - -2 _ t -.t-

15 - _ - ^ - —_ L S

-J- -r

14 1- -,±r t 1 - I

' "^"-"x L ' 13 - -.^ ""^-""s 1 - t v :

S ^ J__ ^ .12 ^ -.^r % ZZZi. . Xii <- -\ S; u 2 S ^^ t i ll 7 \ -i — —

^^ -, ^ t^r ^ 1 ^

.10 ^ Jl _ S- _ ______ At ^2 - — , - ^L.

^ V 2- 09-2^ ^ -< 7 ^ ^r- ^7 J _ S ?f

08 Z^^ ^^^ „__ __ ^-r—,Ll .VO h K^ S*^*\ -^— — —. --. .-Tf-

i >. .s r ^ -.-• '" 1 .07 ^ x- _^ 3 ^-^ ~~ t • 2___ __ __ __ ^^_ *: _ _£ _ _ _ _ _____ _,z_ __ ______ ---* - ^ _7

06 c ^_ ^ s; 7 *

S TT

05 v- S . vU V £ L £

04 ^ 7 . V* ^^ S _^. _ 'Z. _ _ 0^

^ _ ^__ _ __ — _ ^ ^

^ ^ .02 -

s>^^

.01 -

1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480

Figure 16 Jasik Feed, Model No. 275, SN 3 (before calibration was added).

in 750 Mc

9 « = = i

8 --=- =

7 --- =

6 = = -: 1 —* : :: , , J

11111 fi '11 H 11 I'll 111111IJ11 ti't'l'li" 1

5 1 1 -1 1

A v rr^r 4a» 5=

.—| 4-2^ U£_ .94 ■*,' __ _ _j . 1—-^

_?■' .* i ,...,. < < ^

t -#: ' ^ ■ ■"". '

3 ..„ " ~ . :^ r'

y l , s ■ ■ : 1 ^,

._. _ j ' '•II ! y

i ! ■ ! y , i 1 j y<5

: ~ _I_IJIILI c r . r ,< it L. it -J- 9 i T:^^ _ it _it _ _ _ HHII i

■■ ■,..'*•' ' ■" ■ '"

s- j S* i . .. _ .._ .. '^ ^

y 1 ■ " !

A'' ' ' i i i y'\ 1 t— 1 i .^ i : 1 , ^ > !

i i

1 ■ " ... - -■ 1 y | | j

T ~r" "1" 1—^^T * T i "_r

1 ' 1 \ ' ! ! I ! ; ' ■ ^\ ! | . ! 1 i .

1 I i 1 _L JJI-' f : _1 ' i i ' ! ' _J J 4- ^ _J 4-"' X-T

r_t 3=---^-= ---r-^,^ _-+J^ -:J^-— -=j=.- t-^r: = "' 4= —1=— =F I*-T--— '— ' : I i-i . I— --r r-— — - - J =B -,'£--,^._z±_: t4r. i_-^-i4^-^^-i-

P—f ^-zg—^^^tf u-^^-- rn-^:--^^1-4^- CI — _. . J—J _ . I—L - - -T* _L. .L ' _( ' _ t

T . . ,_., :_ z—. t^rr i. T:_-J— -X T -; X- ' ■ • - 4~ 1 "' i ~ 7x M"2 ,. -pf: ^-=n=r ^f-f-l-: i P^-^-.EÊH-; f j - -j=fb ^fH=E4- -^Z^ --• -- . ; -t_ __r^ pi ^^t J^

-Ft^ ̂ ^-1^ =__ j=,^ fr:.4r.^_t_Tt - .-p+-i^K -44^- Ff4t T^4 r-^pMr-fT *-- f r-H -t -'• ^4 T^ H -- "& __]_ .j 4 t__-__.l_L.4_ -- -L44 4 \ p ._*- >C i —>&- : t__i 4-J-_. T_u -L_ — i .j._.■ . 4_i .i-.^^-Lj- : - « p^ 4^3"t^H^4^j îijX|-Lj>j2 H": ;

-l-Li—'—i i 1 1 1 [ 1 i 1 [ 1 1 1 1 1 l--i—1—i--!—1 t-T-*-^ t-*—"^-^1

. j. u^^n-j- \-X~~1— - JLt-4-4-- t—M-i^-'-, - _!_-4_i_ r-

-L-P- ._| T._L

-1—1-4- i+hf 4=^4i'- F-i-l-M-l-'--M414444-t-H-H4-^-f- 4 ^--+ J i—j—■ 1 j—, f— !—J 1— 1 1 r_— ' i ' i i ii i i ' ' ■i ■■ f 1 • f - ' : i r ■ . ■ 'I'M ' i M i 11 '

—^*i -- f-4 r -, i-i 1- -1 1 ' t : ; . 1 1 ' ! ! i , • i iii 1 ' , I ! 1 ' ! hi , * : r . ^ • ' * ^ ' ! > ' 1 '

ITT- 1 j . , - - -}- j-j j , | ■■ - ■ -j h j .•* ? 1 ■■■-■■-" \-\ M ' ' : ' 1 1 j i ' " ' < ' 1 'Ml • ' i <>r i ! '

i 1 ! Mi : M ' <■ • ' ' : - M • i 1 1 • ' ' ! 1 . I

i ' Ml M ! 1 M ' ' !

i M ! • ' ,-'• 1 MM ' j M ■ _, fL ^J _+ _4_._i.lJ. _^**4__l_ __ ! II- i ■ ' ■ i 1 M ^ .! • ! | 1 1 i ! 1 ' LK " 1 1 1 , ■

, rtr -2 in,T+li M ' J---'I I I vblti i 1 ^ j i !.- j 1 Figure 11 . i r i 1 . —,,

ili iM ix - - • ' L-^ i i . ' ' "" 1 ' 1 M i^. ..... 1

1 -A* ' i . - - .it"' , 1 r . t" - ! , • _1 .. . 4.. , • ■ Lx 1 -■-,-. }- ■ --4- ■- - ■ ■ ^^ ■ •■"■ i ■■ ■" ""t " • ■-;■!■: ' M '

.-^ i i i i | 1 1 ■

irf' 'i ■ ■ i i - - ■- i - .. . . i - i , i 1

'T1 ■ ■ i i i ' r " " 1 . ^ j i , j i •' , ' Mi'! , 1 ■ ; ' j • i 1 1 : • t it - ■ ■ • 1 .. .. . , i ! ' i

i , 1 L ,.,.,. _ 1 1 ! 1

db

1400 Mc

Figure 19

Figure 20

SWITCH

MIXER -> 3^ Mc OUT

Figure 21

F»:n N/ SKYHD^l

MPC

AilPLIFIaF. /

KLXEH PREAKP

> 30 Kc

Figure 22

VTVTi

< ^ IS DS T

TEST __ ' 1 DCT. Ik HAC I—i

STASDARD RECEIVER

mam*. iO He AMP .ITTFS,

7$0 Mc CALIBRATION NE-£l

lUlC Mc Calibration NE-51

Figure 2h

FEED

AIL ARGON SOURCE

NAHQA.

DIR, COUPLER

AEL SWITCH

Figure 2$

Documents

NATIONAL RADIO ASTRONOMY OBSERVATORY Green Bank, … · Vn. Thermal Calibration The thermal calibration was by inserting a directional ooupler and an argon noise source into the systems