144 MHz 1500w Larcan

$900 plus shipping (typically around $150)

FOR SALE: 1500 WATT LARCAN 2 METER AMPLIFIER **** $900 + shipping

The amplifier is one module out of a Larcan 30,000 watt television transmitter

for [legacy, analog] TV channel 5 or 6. Each of 24 modules in such a transmitter is

capable of 1500 watts. This is ONE modified module. It uses six MRF151G LDMOS FETs. I

provide a BNC-F input and N-F output connector, and two terminal Bias Jones strip.

This module is tested and typically requires about 54 Amps at 50 volts dc and less than

30 watts input to drive it to full 1500 watts output. It will do 1500 watts key

down all day long for you JT65 folks, if you have an adequate power supply

and good fans. I use four muffin fans for cooling (not included). See photo8.JPG

Blank Aluminum heatsink covers are included.

I had to significantly modify this to get it on 144 MHz. I used a modified N4NGZ

modification procedure. I had to do the following:

1. Remove 81 chip capacitors and six inductors.

2. Install about 30 chip caps in some of those locations with new values.

3. Add six 1/4 wavelength coaxial delay lines

4. Add about 20 jumpers on the PCBs.

5. Change input and output connectors to BNC-Female in and N-Female out.

6. Add a terminal strip for a bias enable line (keying line).

7. Remove existing power connector.

I.e., this was not a trivial modification, but provides very good results. It

requires 25 to 30 watts to drive it to full power output. Overdriving can

cause failure, so care should be taken to avoid this. VSWR protection circuit

is provided, but I have not tested this. It can sense reflected power and disable

the bias.

My FT-736R barefoot drives it to full power. Typical performance

measures as follows:

15 watts input = 1000 watts output @ 40 Amps

27 watts input = 1500 watts output @ 52 Amps

Key-line (enable) switched by normally open contacts. This will switch the 39 volt

bias line which appears on the included terminal strip.

Amp needs to have a good 50 Ohm match. 1.5:1 maximum VSWR. Exceeding this can cause

failure, usually blows one or two of the MRF151G which cost around $80 each.

Schematic and documentation is readily available on this amp.

As is, this amp weighs about 35 pounds. It measures about L/W/H 23 x 17 x 3 inches.

I build a wooden crate for shipping and total weight is about 21 kg (46 pounds).

Questions? Contact Mike at kl6m.com