Triode-manual.pdf

THE TRIODE BOARD

Control and Protection

for your

Triode RF Power Amplifier

All the hard work done!

• Protects your triodes

• Grid and anode current metering

• LED status indicators

• Warm-up timer

• Adjustable regulated cathode bias

• TX/RX switching and relay supplies

• Simple wiring to one PC board

• Easy to build – clear 'how-to'

instructions in this User Manual.

Versatile!

Use with one or two tubes

including 3-500Z, 3CX800, 8877/3CX1500,

GS35b/GS31b, GI7b, TH308, YD1336...

The Triode Board: AN-2

Issue 1.7 for board v2.4, June 2011

Á 1999-2011 IFWtech Limited

N WARNING

These notes are intended for users who have sufficient experience

to work safely with high-voltage circuits.

Use at your own risk! We cannot accept responsibility for any

damage or injury.

DANGER - AC mains voltage and high DC voltages!

AN-2 Issue No

Triode Board Issue No

Revision Details

1.0, September 1999

2.4

(first production boards)

Revised after extensive pre-release testing.

1.1, October 1999

2.4

R24 changed to 3K3; note about HV metering.

1.2, April 2000

2.4

Minor updates and typos, change of Internet and

WWW addresses.

1.3, January 2002

2.4

Minor updates to Components List.

1.4, April 2002

2.4

Updated Components List, and part numbers in

schematics and main text

1.5, April 2002

2.4

Reformatted to A4; new US distributor; included

AN-5 as Appendix 1

1.6, July 2008

2.4

Tubes table expanded, high bias mod merged

into main text, updated Components List.

1.7, June 2011

2.4

Further updates to Components List.

REVISION NOTES

‘European’ Component Markings

‘R’ in resistor values means W , e.g.

15R = 15 W , 3K3 = 3.3k W , 1M0 =

1.0M W etc.

For better readability, the multiplier

letter replaces the decimal point,

so 0R33 = 0.33 W , 1K0 = 1.0k W etc.

The same applies to small

capacitors, e.g. 4n7 = 4.7nF

(nanofarads) = 4,700pF.

The Triode Board: AN-2

Issue 1.7 for board v2.4, June 2011

Á 1999-2011 IFWtech Limited

CONTENTS

Features......................................................................................................... 4

Introduction................................................................................................... 5

2.1

What You Get....................................................................................... 5

2.2

What You’ll Need.................................................................................. 5

2.3

Choosing Configuration Options .......................................................... 5

Triode Amplifier Control and Protection .................................................... 6

3.1

Grid and Anode Current Metering ........................................................ 6

3.2

Meter and Surge Protection.................................................................. 6

3.3

Grid Current Protection ........................................................................ 9

3.4

Cathode Bias ...................................................................................... 10

3.5

TX/RX Switching ................................................................................ 12

3.6

24V Relay Option ............................................................................... 12

3.7

PTT Options ....................................................................................... 12

3.8

Warm-up Timer Options..................................................................... 13

3.9

RFI Protection..................................................................................... 13

Using Your Tubes and Meters................................................................... 14

4.1

Which Tube – or Tubes?.................................................................... 14

4.2

Choosing and Using Meters ............................................................... 15

Building the Triode Board ......................................................................... 17

5.1

Mounting the Board ............................................................................ 17

5.2

Board Modifications ............................................................................ 17

5.3

Assembling the Board ........................................................................ 17

5.4

Building the LED Array ....................................................................... 19

5.5

Building the HV Divider....................................................................... 19

Off-line Testing ........................................................................................... 21

6.1

Meters................................................................................................. 21

6.2

Cathode Bias Adjustment................................................................... 23

6.3

Control Logic and Alarm Settings ....................................................... 23

Interconnections......................................................................................... 26

7.1

Mains Power Control .......................................................................... 26

7.2

HV Control and Safety........................................................................ 27

7.3

CHASSIS GROUND Connection ....................................................... 27

7.4

RFI Suppression................................................................................. 27

Power-Up ..................................................................................................... 28

8.1

First Switch-on.................................................................................... 28

8.2

Cathode Bias Adjustment................................................................... 28

8.3

RF Testing .......................................................................................... 28

Schematics ................................................................................................. 30–34

Updates and Product Support................................................................... 29

Components List ............................................................................................. 35

The Triode Board: AN-2

Issue 1.7 for board v2.4, June 2011

Á 1999-2011 IFWtech Limited

1. Features

All on one PC board – simplifies external wiring

• Cathode bias supply: adjustable 3-30V, precision regulated up to 2.5A or more.

• Grid and anode current metering, with meter protection.

• Status output to four LEDs.

• Relay TX/RX switching.

• Warm-up timer – also controls High Voltage.

• Grid current and HV monitored – protects sensitive grids from overdrive.

• Anode current monitored for surge protection – also controls your High Voltage

supply.

• 12/24V DC supply for external relays (uses external mains transformer).

• Highest RFI immunity – high-level CMOS logic, extensive RF filtering and

groundplane shielding.

• Quality double-sided PC board measures 5.7in x 3.3in.

• Designed for ‘key down forever’ reliability.

The Triode Board: AN-2

Issue 1.7 for board v2.4, June 2011

Á 1999-2011 IFWtech Limited

2. Introduction

2.1 What You Get

To give you the best possible value for money, we do not supply expensive ‘off-board’

components such as meters, transformers and large heatsinks. You can probably find these

components much more cheaply as surplus.

The full Triode Board kit includes:

1. The PC board, double-sided with plated through holes and printed component locations.

2. All the on-board components – premium quality for reliability. To cover almost all possible

combinations of tubes and meters, the kit includes a range of resistors of various values.

3. Power transistor (Q1) and mounting kit (but not heatsink).

4. Push-on tags for board connectors.

5. Complete schematics and this User Manual .

The ‘bare board’ option is the Triode Board with this same User Manual .

2.2 What You’ll Need

Most of these additional components are easier to buy surplus than at new prices, so we didn’t

include them in the kit. See Section 5 for more details about these components.

1. RESET switch: SPST momentary push-button (low-voltage).

2. STATUS LEDs: two red, one green, one yellow or blue, all ordinary 20mA types. See Section

5.4 for details of how to build the LED array.

3. Heatsink for Q1: 4in x 3in x 1in, or equivalent (2°C/W or less). For low bias voltages and

lower-power tubes, you can mount Q1 on a cool area of the chassis.

4. Metal mounting pillars and hardware for the PC board.

5. M1 (grid current): 0–100 µ A moving-coil meter recommended. See Section 4.2 for details of

meter selection and recommended scaling.

6. M2 (anode current): 0–100 µ A moving-coil meter recommended. See Section 4.2 for details

of meter selection and recommended scaling.

7. Transformer: for 12V relays, use 15V AC at up to 1A; for 24V relays, use 20V AC at up to 1A.

This transformer winding must not be connected to the transformer winding for the tube

heater.

8. HV divider, to provide a 12–15V ‘HV present’ signal (and also act as a backup bleeder chain).

See Section 5.5 for details of construction.

You will also need a few temporary components and a multimeter for the setting-up procedures.

2.3 Choosing Configuration Options

Every power amplifier is different, so there are many possible options for cathode bias voltages,

metering etc. Sections 3 and 4 give full details.

The Triode Board: AN-2

Issue 1.7 for board v2.4, June 2011

Á 1999-2011 IFWtech Limited

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