Racal 409 Modulation Meter FM AM Mod Meter

Circuit Diagram, Service Manual, Service Information,  Schematic Diagrams and Manuals

For Repairing, Restoration and Servicing of Vintage and Modern Electronic Equipment

Manual with Circuits
& Layouts Available
Details Below
As a Download

Click Here

Circuits & Manuals
Military, Radio, TV, 
Amateur & Marine
World Wide Service
For Lists Click Here

Use R/H scroll Bar
More information below

Radio's For Sale Click Here

Military and Broadcast
Radio Ads 
Click Here

Military Radio Home Click Here If no Index to the left

Modulation Meter Type 409
A wide range highly sensitive instrument, designed to measure percentage amplitude modulation (a.m.) of carriers from 3 - 1200MHz and frequency deviation (f.m.) on carriers from 3 - 1500MHz.
The meter scales for AM are : -
0 - 10%
0 - 30%
0 - 100%

The meter scales for FM are : -
0 - 3k Hz
0 - 10k Hz
0 - 30k Hz
0 - 100k Hz
0 - 300k Hz
0 - 600k Hz deviation.

Outputs at the intermediate frequency (nominally 1MHz) and at l.f. are available at front panel terminals.

An in built switched noise filter permits measurement of very narrow f.m. deviations using a sensitive external I .f. millivoltmeter.

Changes in mean carrier level when a.m. is applied can be measured to better than 1% accuracy and effective i.f. limiting permits measurement of spurious f.m. on a.m.

An f.m. calibrator circuit, which can be checked directly on an electronic counter, is provided within the instrument to enable periodical calibration to be carried out.

Tuning the instrument at very high frequencies has been simplified by the provision of a fine tuning control and a SET l.F. position on the meter switch.

In this position the tuning control is simply adjusted until the meter reads to the SET l.F. mark, thus eliminating tedious peaking procedures.

The instrument is fully stabilised against changes in mains supply voltage of 10% from the value set on the mains voltage selector.

The power consumption is approximately 120 VA.

The instrument is supplied in a metal case with quickly detachable top, base and sides.

A rack mounting kit is available.

Racal 409.jpg (44880 bytes)

Manual with Circuits
& Layouts Available
Details Below
As a Download

Click Here

The Manual Consists of  the Following :-



Tuning Procedure 
Measurement of Amplitude Modulation 
Measurement of Change of Mean Carrier Level 
Measurement of Frequency Modulation 
Monitoring Facilities 
FM Calibrator 

External Oscillator Facility 
Anti - Microphonic Turret Mounting 
Measurement of a radiated signal 

Input, Mixing and IF Amplifier 
AM Measurements 
FM Measurements 

Fault Finding 
Preset Controls 
Adjustment of RV1 
Adjustment of RV1O 
Adjustment of RV5 
Alignment of the IF Amplifier 
Adjustment of RV3, RV6, RV8, RV13 and RV14 
Adjustment of RV15 
Adjustment of RV12 
Adjustment of the Preset Components of the FM 
RF Alignment 
Voltage Measurements 


Manual with Circuits
& Layouts Available
Details Below
As a Download

Click Here

Racal 409 Modulation Meter FM AM Mod Meter
Manuals are Available Worldwide as a Download.

Manual with Circuits and Layout images 59 pages
Manual 59 A4 pages worldwide

( For all Payment Options )
( Please Click the Payment Links Below )

We do all we can to provide the very best that is available for you.
But in the unlikely event that any data should not be as you expected.
A refund is always available. Kind Regards Allen and Alanna.

Manuals are Available Worldwide as a Download

Thank you for your interest. Allen and Alanna G0RIT
Should you wish to purchase

For Worldwide Prices Payment Options and Delivery Details



This Website is Copyright
Copyright 1999 [www.shopingathome.com/Military Wireless]. All rights reserved.
Please ask before using any images or text thank you.

Revised: February 09, 2021