Harris Amplifiers

Harris linear amplifiers RF-353 and RF-355

How to use them WITHOUT the Harris transceiver RT-1446

by F1FRV

* December 2009. Original issue *

* March 2010. Added internal link to antenna tuners *

* May 2013. General update of control systems *

What about these Harris amplifiers

Both are full automatic amplifiers, 1.6 to 30 MHz. They are part of the " RF-350 " line, widely used since the 88's (and still today) by armys and civil aviation networks. The RF-355 is equiped with a 3CX800 and given for 500-750 W, the RF-353 with a 3CX1500 given for 1000-1500 W (24/24, 365/365, -30°C to +50°C, up-to 3000 meters ASL). But, they are full automatic, only when driven by the RT-1446 Harris transceiver, thru a serial link and specific protocol. As they are, without modification, they can be tested (and used) in "manual" local mode (only an external 12-14 VDC @ ~150 mA supply is required).

The purpose of the modifications is to have them working automaticaly, with any ham transceiver. Maximum power can also be safely increased, up-to 1 kW for the RF-355 (3CX-800), and up-to 2 kW for the RF-353 (3CX-1500). Due to the noise produced by high speed 400 Hz blower, it is quite mandatory to have amplifier outside the shack, and remote controled.

Harris technical documents available

Download RF-355 / AM-7223 (3CX-800) Operation manual.
Download RF-355 / AM-7223 (3CX-800) Service manual.

19" rack, height 18 cm, depth 52 cm, weight 29 kg.

Download RF-353 / AM-7224 (3CX-1500) Operation manual.
Download RF-353 / AM-7224 (3CX-1500) Power Supply Service manual.
Download RF-353 / AM-7224 (3CX-1500) Amplifier Service manual.

Amp: 19" rack, height 27 cm, depth 51 cm, weight 18 kg
Supply: 19" rack, height 27 cm, depth 51 cm, weight 65 kg

General description of operation

Step 1
Inside amplifier, detection of the band to to be used by the automatic band decoder, which will then move the bandswitch to the right band.
This is done, amplifier in by-pass, when you tune the antenna coupler, or transmit without amplifier. Power >= 5 Watts is required.

Step 2
With amplifier in service, make the “ Tune For Max “, either manualy, or automaticaly. This vary the tuning coil inductance inside amplifier output PI network.
This is done in the remote control box, either with a manual switch CW / CCW, or with the automatic “ Tune For Max “ board. Power >= 20 Watts is required to tune the amplifier.