te-1452g 144 mhz, 400w solid state amplifier repairings...

F5DQK jan 2008, rel 02 1

TE-1452G 144 MHz, 400W solid state amplifierrepairings & modifications


Réparation d’un ampli VHF TE-Systems 1452G

- Ampli reçu en état de marche , mais au contraire des marques concurrentes ne « digérant »pas plus de 25 Win …ATTENTION et PRUDENCE !!!!- A la suite d’une fausse manipe (entrée micro de l’IC-706MKIIg oscillant facilement), les 5 transistors ont rendu l’âme en un rien de temps !- Au contraire des marques concurrentes (Mirage, RFC, Tokyo Hy Power, etc.. AUCUNE PROTECTION du constructeur n’est prévue en cas de puissance excessive sur l’entrée RF, et de sortie avec TOS prohibitif !!- Platine epoxy commune aux versions 50, 144 et 432 MHz pour Pout>200W

Ce PPT illustre les faits suivants:

- Subtitution des 5 transistors MRF247 et précautions à prendre- Correction des nombreuses erreurs du schéma de principe (voulues par le constructeur)- Addition d’un fiche PTT Cinch RCA pour être en phase avec la concurrence- « Strap » du transistor driver permettant une Pin maxde 60W au lieu de 25W et autorisant ainsi l’emploi de tout TRx moderne. Correspond à la version TE 1454G- Mesures RF Pout fonction de Pin AVEC et SANSdriver.

Améliorations apportées:

- Alimentation +12V pour préampli de mât directement à TRAVERS de l’ampli (fini le sequencer)- Meilleurs circuits de linéarisation (prochaine modification)


- CAUTION: original version with driver doesn’t accept more than 25Win- The IC-706MKIIg mike input is very RF sensitive … and’d QRT the 5 x MRF247- Absolutely no Rf in overload or Rf out protections !!!

TE-1452G AS RECEIVED FROM UK


Repairing & modifications steps- Substitution of 4 times MRF247 in both parallel final stages & the MRF247 driver- Bypassing the driver with a coaxial cable allowing now 50 to 60W in = TE-1454Gwith reverse possibility to use the driver again (only allowing 15W max input)- PTT socket addition (RCA type)- Schematic mistakes corrections- Direct DC feeding compatibility addition for mast preamps (no more sequencer…)- Better biasing circuit (in a nearest future)

First note

TE-1452G printboard

Mother printboards on TE 0552G, 1452G and 4452G models with Pout>200W are exactly the same (also RA versions)

- CAUTION: original version with driverdoesn’t accept more than 25Win- Despite of other brands like Tokyo Hy Power, Mirage or RF Concepts, TE-Systems amps have absolutely no Rf in overload or Rf out protections !!!- The IC-706MKIIg mike input is very RF sensitive … and’d QRT the 5 x MRF247


TE-1452G printboard before repairing


TE-1452G schematic

Many errors in the initial scheme !


TE-1452G printboard after repairing

Substitution possible only after desoldering all previous metal clad mica capacitors on base and collector sides

Little teflon coax for driver bypassing


TE-1452G : driver cap position on base side

After repairing

Min distance ! Not optimized

Normal target (other new amp)

10 pF ?


TE-1452G : final cap position on base side (1 of 4)

After repairing

Min distance ! Not optimized10 pF ?

Normal target (other new amp)


TE-1452G : one final stage after repairing

10 pF ?

40 pF ?

1 nF

40 pF ?


TE-1452G : driver changed but « passed through »

- more RF input power (>50W instead of maximum 25W)- no more transistors overloading & shutdown- possibility to connect the driver again as formerly (+ collector & base DC inputs)

10 pF ?

40 pF ?

10 pF ?

Little teflon coax for driver bypassing


TE-1452G : DC bias

Ic=100 mA

Ic=100 mA per transistor

DRIVER39Ω, 10W 3.3Ω, 0.5W

FINAL

6.8Ω, 1W

50Ω, 5W

1N9001


Initial bias switching

Mod bias switching allowing now direct masthead preamp feeding with IC-910H or FT-736r rig

- Guardian 1st contact used both for Rfin and DC biasing injection

- DC biasing is now given by a 2nd separate relay- Guardian relay contacts only used now for RF switching

+12V DC in Rx position always present on all collectors & circuitry, except for the DC biasing

TE-1452G : mods for mast preamp DC feedthruBefore

After


DC on Guardian relay in Tx mode

GND

DC for preamp

Preamp & TRx relais DC feeding

RFout

RFin

TE-1452G : mods for mast preamp DC feedthru


DC bias feeding with RF shoke between RFin and TRx relay

input (under VOX_PTT printboard)

Rfin cap (must be taken off)

1nF cap (must be taken off & placed between collectors

and Relay RF output)

RFin

RFin

RFoutBefore

After

DC thru

1 nFa/ DC feedthru for masthead preamp direct feeding



2nd DC shoke (DC bias extracting)

+12V preampPTT line

Rx +12V Tx 0V

From +12V switch amp on

+12V DC bias whith

Txing

50 Ohm RFin line + DC bias

GND


Before After

Now DC biasing injection from the rig to the masthead preamp is possible

b/ DC bias separation from RF

Separated bias relay


TE-1452G: on board GaAs preamp

Preamp RFout & +12VAmp in

Preamp RFin

Amp out



Before After

c/ Separate preamp DC feeding

DC shoke (preamp DC bias feeding)

DC shoke : 1 pin desoldered

Added DC wire soldered now to

relay feeding



Preamp out & +12V DC feeding shoke

7805

LCin

Autopolar Radj for Vsource =1V

Vd Radj

LCout

Preamp in + DC shoke

Top view

Gate

Drain

Desolder here



Bottom view

RF protection with 2 diodes in each transistor

2 CMS caps for GaAs source RF biasing

+12V & preamp RF out

Preamp in & DC shoke



d/ Gain / Nf measures

Insertion losses Preamp meas

HP-8970a noise / gain analyser + Ailtech 7615 noise generator


TE-1452G : VOX scheme

Too high resistor, half value is sufficient


TE-1452G : VOX & PTT printboard mod

To TRX Guardian relay

GND

22 kΩ in parallel to the 1st one

Initial DC biasfeeding coil BEFORE Guardian TRx relay

With 11 kΩ, the VCE sat in the relay PNP transistor is now 1.5V instead of 4V initially !!

Bottom position


TE-1452G : rear of front panel

TE 1406 printboard


TE-1452G : adding of PTT cinch socket on rear panel

+12V arrival

- The initial remote accessory socket in normal & G versions has no utility- every other brand has a PTT cinch connector


TE-1452G : printboard connectors pin layout

1 2 3 4 56 7 8 9 10

1 2 3 4 56 7 8 9 10Front panel with switches & LEDs

Rear panel with RF in/out connectors

Output J3 remote plug10

General +12V incoming9

+12V after thermal security8

Preamp & LED switch7

Ground6

NC5

PTT or remote LED4

+12V after amp on switch beforethermal security

3

DC bias & RF LED2

FM/SSB switching1

On/off connector 1 nearfront panel

J3 SSB delay pot10

PTT from 4 conn 19

FM/SSB switching from 1 conn 18

+12V from 3 conn 17

Output on J36

Output LED to 7 on J35

Ground4

DC bias output3

Guardian TRx relay2

Preamp relay 1

RF switching connector 2 near rear panel


TE-1452G : J3 remote plug

LED cntrl gnded7

Ground6

PA cntrl gnded5

Preamp4

+12V, max 1A3

PTT2

FM/SSB1

J3 remote plug

J3 connector(not used in RA version)

Cinch PTT connector

+12V arrival

1

7 6 5 4 3 2


TE-1452G: RF power measures


0.6750.6700.6500.6250.626VBE (V)

8

12.5V

14

13V

33

13.8V

30

13.5V

4.5Ib bias (mA)

12V

TE-1452G biasing current

MRF247 driver

0.6620.6470.6350.6130.592VBE (V)

0.7

10

12.5V

2.22.01.90.4Ic total (A)

22

13V

75

13.8V

48

13.5V

6Ib bias (mA)

12V

4 x MRF247 final stages


TE-1452G: Pout versus Pin à 144.400 MHz without driver

35.833031029027745

35.833031029027740

39.1

34.2

31.9

29.8

27.3

24.4

21.5

16.5

14.4

I à 13.8V (A)

350

305

277

250

212.5

175

132.5

75

56

13.8V

52.55047.53.25

200182.517520

230225212.525

260250232.530

305

275

150

115

65

12.5V

68605

1225.11010

162.514015

325

282.5

13V

282.5

262.5

12V

50

35

Yield

%

Pin (W)

- Rig IC-706MKIIg, Pin from 3.2 to 50W- Wattmeter Telewave model 44A- Dummy load BIRD Termaline 8135 - 150W- MAAS SPS9600 power supply à 13.8V

=TE 1454G=TE 1454G


TE 1452G without driver at 144.35 MHz: Pout/Pin

50

100

150

200

250

300

350

0 10 20 30 40 50Pin (W)

Pou

t(W)

10

20

30

40

50

60

70

Pout (W) à 12V

Pout (W) à 12,5V

Pout (W) à 13V

Pout (W) à 13,8V

I (A) à 13,8V

I (A

mps

)

U=13.8V

Pin allowed now up to 60W

I @ U=13.8V

=TE 1454G=TE 1454G

U=12V


35.855.1854.4246.53

35.855.1854.4246

39.1

34.2

31.9

29.8

27.3

24.4

21.5

16.5

14.4

I à 13.8V (A)

55.44

54.84

54.42

53.98

53.27

52.43

51.22

48.75

47.48

13.8V

46.7735.12

52.4343

53.2743.98

53.6644.77

47.7837

50.4140

51.4641.76

54.51

54.19

12V

46.99

45.44

Pin dBm

- Rig IC-706MKIIg, Pin from 3.2 to 50W- Wattmeter Telewave model 44A- Dummy load BIRD Termaline 8135 - 150W- MAAS SPS9600 power supply à 13.8V

=TE 1454G=TE 1454G

TE-1452G: Pout versus Pin à 144.400 MHz without driver


TE 1452g without driver à 144 MHz: Pout/Pin

46

47

48

49

50

51

52

53

54

55

56

35 37 39 41 43 45 47 49Pin (dBm)

Pou

t (dB

m)

Pout (dBm) à 12V

Pout (dBm) à 13,8V

U=13.8V

U=12V

P1dBc=55.4 dBm or 348 W

P1dBc=54.5 dBm or 282 W

=TE 1454G=TE 1454G


TE-1452G: Pout versus Pin à 144.400 MHz with driver

47.8

45.8

44.3

42.8

42

40.5

36.7

32.6

I à 13.8V (A)

382

375

370

360

350

330

280

225

13.8V

1801551351

31027524010

32028226015

32530027020

300

262

245

200

12.5V

2301752.5

2802125

3002307.5

332

13V

275

12V

25

Yield%

Pin (W)

- Rig FT-847, Pin from 1 to 25W- Wattmeter Telewave model 44A- Dummy load BIRD Termaline 8135 - 150W- MAAS SPS9600 power supply à 13.8V


TE 1452G with driver at 144,35 MHz: Pout/Pin

100

150

200

250

300

350

400

0 5 10 15 20 25Pin (W)

Pou

t (W

)

30

40

50

60

70

80

90

Pout (W) à 12V

Pout (W) à 12,5V

Pout (W) à 13V

Pout (W) à 13,8V

I (A) à 13,8V

U=13.8V

I (A

mps

)I @ U=13.8V

Original manufacturer version !!

- Max SAFE Pin allowed <25W- Sat Pin 10W !!!!!!

U=12V


QRO 2 meter amps comparaison

0

50

100

150

200

250

300

350

400

0 10 20 30 40 50

Pin (W)

Pou

t (W

)

B-5030-G Pout (W)

HL-350Vdx Pout (W)

TE-1452G Pout (W) without driver

U=13.8V


Aknowledgements-- Special thanks to Jim W3ATV who’d sell me this « technician special » amp, also to many US hams but especially Jeff Allen KB9YSJ from Los Angeles, Dave WB0GAZ, David W3KM, Don N8ECH, KT0WN, John VE3MPH, Maximo EA7FGJ and many others for the precious help I’d get and the veryconstructive discussions we’d have about-- Also to many french hams who kindly’d give me complementary US screws vy difficult to find here in W-Europe !!!-- The AD5TH site also gives many infos about TE Systems six & two meter amps

te-1452g 144 mhz, 400w solid state amplifier repairings...

Documents