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Showing posts from September, 2024

1200W HF Linear Amplifier from budget parts - 2

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While I'm waiting for the rest of the parts to turn up, I have started working out how to automate band-switching on the Low-Pass Filter module.  To do this, I am relying on the output of my IC-7300 transceiver to control this. If you want to skip ahead, the source code is located on my GitHub page:   https://github.com/au-chrismor/arduino7300 As noted in part 1 of this series , the IC-7300 outputs a voltage from 0 - 8V depending on the band selected.  The approximate values (from IC-7300 forums) are listed below: 630m     7.41V 160m     7.41V 80m        6.07V 60m        5.07V 40m        5.07V 30m        0.03V 20m        4.07V 17m        3.18V 15m        3.18V 12m        2.22V 10m        2.22V 6m          1.88V   My LPF has switch inputs for: 10/12m 17/15m 30/20m 40m 80m Fortunately a lot of these will line up, at least for my usual bands. However there seems to be a bit of dispute about the actual voltages.  Icom don't publish anything, which is not entirely surprising.   My

1200W HF Linear Amplifier from budget parts - 1

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This is either going to go very well or very badly, and if I'm honest it's 50/50 right now... I was scrolling through AliExpress (who doesn't?) and I came across a listing for a 1.2KW 1.8-54MHz LDMOS amplifier for a little over $A100.  Of course for this, it doesn't include the BLF188 device ($A300 from DigiKey).   Unlike most of the other amp packages on these markets, this one is assembled except for the LDMOS device, so there's no trying to interpret the schematic only to find it has nothing to do with the PCB you have on hand.   It didn't take long and the module arrived at my local post office.  It's small, at less than 100mm x 100mm and it appears to be quite well made: My research also tells me that a multi-band Low Pass Filter is an excellent idea and fortunately the same vendor has a nice unit at about twice the price of the amplifier module.  It arrived in the same package:   At about 250mm x 200mm it's substantially bigger than the amplifier,