Here's an account of getting the Bitx40 on to Winmor on USB, from a ham who was first licensed in 1963, and who has been completely out of the hobby for decades.? Not much new to report here, just a confirmation of what others have noted, and a tip of the hat to those kind souls who have posted their knowledge here.
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In Oct 2017, I purchased the board from Farhan at HF Signals, and a case from Sunil at Amateur Radio Kits.In.? Both arrived quickly.??
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The case saved me the effort of trying to turn my kitchen table into a metal fabricating shop (cutting a square hole for the display would have been an adventure).? The case's pre-drilled holes fit the Raduino assembly (with the included standoffs) perfectly, and the holes in the bottom of the case were perfectly aligned with the circuit board.? A well-made case.? The case came with some parts such as a 10k pot to replace the original with the small shaft, a couple of knobs, antenna and audio jacks, and a fuse holder with 3A fuse.? Nice touch.??
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I am powering the unit with a large 12 volt AGM battery.
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After connecting the board, on the "Wire up" webpage on Farhan's website I immediately jumped in with number 1 on the "Alignment" list, not noticing the phrase "pre-aligned out of the box".? My failure to RTFM.? No harm done, as I became better acquainted with the unit's driver and final.??
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With the PA disconnected, I found my unit draws 150 mA on receive, as expected.? But it seems to draw more current on transmit than expected (280 mA with the PTT pressed, no audio in the mic).? This is mildly troublesome.? Perhaps RF is getting into my VOM on transmit and causing it to deceive me.? Whatever.??
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With the PA connected, I slowly set the PA current to 100 mA, which put the gate voltage at 4.0.? Speaking into the mic brought the TX current up to about .7A.? My SWR/Power meter reads only 3 watts out when I say "Ah" into the mic (though I'm unsure how accurate the meter is).? Good enough for now.? I have read here that there can be a low drive issue with these units.? The final doesn't get warm, and that's a big plus.
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Tuning around with a hastily erected dipole, I heard a ton of very loud QRN.? I happened to have recently purchased a $22 SDR dongle that amazingly receives DC to light, and when I attached it to the dipole, it revealed a comb-like pattern of regularly spaced noise spikes throughout the lower HF spectrum.? I immediately started thinking malevolent thoughts towards my neighbors, the power company, and the modern world in general until I noticed that the noise spikes disappeared when I unplugged a certain 12 volt adapter I sometimes use in my house.? I contritely hung my head and carried on.
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I added a 3 watt diode in series with the Bitx40 +12 supply, to guard against any fat-fingered misapplication of reversed polarity voltage.?
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I found the tuning clicks a bit much, but they were easily remedied with a series 6 ohm resistor and a couple of caps paralleled on the Raduino +12 line.
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Using my SDR dongle I was able to listen to my own voice transmitting into a dummy load.? The audio sounded fine.? This SDR dongle is absolutely worthwhile as a piece of test equipment.?
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I wanted to use the Bitx40 for digital modes, and Winmor in particular, so I modded it to work on USB.? After reading several threads on this forum, I decided on the hardware approach (I am not interested in QRP voice operation, therefore a "permanent" mod to USB-only was OK.? Furthermore, I'm an old guy who understands more about linear circuits than about programming.? Raduino sounds to me like something I'd find at the farmer's market.)? So in order to bend the BFO for USB reception, I replaced the L5 jumper with a 5.6 uH inductor, and inserted a 2-23 pF trimmer into the holes for C103.? I adjusted the trimmer for zero beat audio at 1.5 kHz dial above an AM commercial SW station.
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Before connecting the unit to a digital interface, I wired a series 470 uF cap into the Mic input line.?
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The digital interface I chose to use is the Easy Digi by KF5INZ, who supplied me with one that has 3.5mm phone jacks for Mic, Spkr, and PTT.? Instructions were included, and were very clear.
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The Winlink software works only with Microsoft, and required that I install Net Framework 3.5 on a Win10 laptop.? This mysteriously turned into a rather frustrating flailex which reminded me of why I switched from Microsoft to Linux Mint years ago.? After some heartburn I got Net Framework sorted out, and got Winlink Express installed.
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A bit of cut and try with audio levels, and I soon made my first Winmor connection.? The RMS gateway I linked with happens to be very close to my QTH, and I suppose calling this "success" is setting the bar low.? I likely still have some tweaking to do.? But at least the Bitx40 works pretty as much as it should.??
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The pleasure of getting this rig up and running compares with that of the first Novice CW contacts I made long ago as a teenager.??
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Hats off to the fine contributors to this forum who so generously share their knowledge, especially KE7ER, KK6WUU, YT5AAA, and others.?? And hats off to Farhan and Sunil!
Rick N3ECZ
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Raj vu2zap
John 2e0eii
Tominaz
_Dave_ AD0B