PROJECT:

Conversion of ITT 1850 MHz Transceiver to 2400 MHz

PURPOSE:

To easily obtain all mode transmit capability in the 2400 MHz band. The ITT transceiver on 1800 MHz is based on an X6 varactor multiplier which may be converted to 2400 MHz ham band. The modified unit will accept power in the 400-420 MHz range from a standard UHF ham transceiver and deliver power on 2400-2520 MHz with an overall conversion efficiency of 25 - 30 % at an output power of 1-2 W.

TOOLS AND EQUIPMENT:

ITT Transceiver
UHF transmitter, 5w at 408 MHz
RF power attenuators and dummy load
RF power meter reading 1 mW to 5W
5/16 deep well socket
5/32 long arm allen wrench

CONSTRUCTION:

Disassemble s-band section of transmitter. Discard PIN diode switch.

Modify s-band filter as follows. Open filter and remove 3 resonators. Cut resonators down to 1-9/32 inch. Reassemble filter.

Reconnect ITT tranmitter components as shown in diagram.

TEST AND TUNE UP:

Insert power meter at output of s-band isolator. Use sufficient attenuators to protect power meter from overload. Apply no more than 5w of 408 MHz drive power to input of UHF isolator. Tune varactor multiplier for maximum smoke. Obtain at least 1 W at 2448 MHz.

Tuning tip: use tiny insulated screwdriver, take care not to load or short adjustment screws.

Reconnect modified s-band filter to multiplier and insert power meter at output of filter. Tune filter resonators for maximum smoke. Tune only the resonators, do not change coupling. Maximum insertion loss 1.5 db.

Tuning tip: use long arm allen wrench inserted thru bore of deep socket, do final tuning of resonators while a slight drag is applied by locknut via finger pressure on deep socket. Think of setting the tappet valves on an old Harley.

Listen with s-band receiver or convertor setup such as shown in diagram. Sounds great, huh ?

HAVE FUN ON 2400 MHz WITH YOUR NEW TRANSMITTER.

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