After discounting a W6PQL based kit, a PE1RKI 23cm 150W Power Amplifier was decided upon.
Like the W6PQL design, the PE1RKI (Bert Modderman) amp uses a pair of XRF-286 transistors, but comes fully assembled and tested AND worked out cheaper (Dec 2012) than stuffing around building your own. It requires 8W of drive for 150W out.
Considering the reports of “fake” XRF-286 transistor out there, or using second-hand transistors of dubious origin and quality, this was a no-brainer.
Take a punt, and spend more on something that might work, or get something that does work.
Of course, you need to integrate this into an enclosure, with appropriate RF switching, and a 28V power supply.
28V power supplies are cheap and easy, these days.
A Meanwell SE-450-24 24V 450W power supply was purchased off eBay for around $100.
Kuhne sell Meanwell power supplies, but it is much cheaper to obtain these off eBay.
At 24V out, this power supply will deliver just over 18A, but has a trimpot to set output voltage above and below the nominal 24V, so even though it is marked as a “24V” supply, it will provide 28V with ease. It can provide the 28V @ 11.2A the amplifier module requires, with some headroom.
The input port can be seen at right, and Bert describes this amplifier module as:
150 watt and is available in 2 versions. both 250 euro.
same ssb output as 8 x m57762 !
8 watt in 140-150 watt amp out.
frequency range 1240mhz – 1280mhz.
8 watt in 150 watt p1db out.
frequency range 1290mhz – 1310mhz.
28 volt 11 amps
N or sma connector input and N connector output.
The “SSB” version was requested with an “N” connector input, but in hindsight, an “SMA” version should have been asked for, because the input side relay is an SMA type relay, and internal coax cable will be semi-rigid UT-141 hardline.
With 141, SMAs are the “go to” connector. N plugs for 141 are just as easy though, and these right angle N plugs were purchased from The RF Shop in Brisbane.
As seen right, Bert provides a data sheet for each amplifier, detailing it’s specifications.
You will also see the power sense circuitry, near the output N connector.
All of this is being mounted inside a 2RU 19″ rack enclosure.
More to come, as progress is made.