My uBITX is alive!!
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David Robertson
Everyone.
Last night my uBITX took ti's first breath of life. Even worked a couple of QSOs. Attached are some pictures. Please note that I installed the 4.7K resister on the radinio board for CW pull up instead of installing it in the wiring with the CW jack on the front panel. Because of the case size I removed the heat sinks from the finals and using mica insulators I mounted them to the back panel. The heat sinks that were supplied had metal ridges on the back that had to be removed so they could mount flat on the bolts that fastened the finals to the rear panel. The radio works on 80 through 10 meters with decreasing power as you go up in frequency. I get about 15 watts out on 80 down to 5 watts on 20. The frequency calibration seems to be very close. In performing the bias adjustment I discovered that I could only adjust the current for each final to about 83 ma with the pot set fully CCW. So to even the shared current of the two finals I adjusted them to 60ma each with the total of 120 final bias current. The little voltage regulator in the final circuit was working correctly supplying 5 Volts to the bias circuit during transmit. Though this radio is not in the same league as my Elecraft equipment it is a radio I can have a lot of fun with. 73 Dave? KD1NA |
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Looks pretty good David, but where you have the Raduino mounted to the display and mounted off the main board, you really should rework the cabling a bit and use miniature coax for the Clock 0, Clock 1 and Clock 2 wires between the Raduino and the main board. ?These are 30 to 50 MHz signals except for Clock 0 which is the BFO and is around 12 MHz. ?Still should use coax as these are the main RF signals that control the rig. ? A better choice might have been to plug the Raduino into the main board and use cabling to connect the Raduino's display header to the display itself. ?Could save RFI from the clock signals from getting into things it shouldn't on the main board and also RF from the main board being picked up by those wires. Jim Sheldon - W0EB ------ Original Message ------
From: "David Robertson" <kd1na363@...>
Sent: 2/14/2018 11:29:16 AM
Subject: [BITX20] My uBITX is alive!! Everyone. |
Jim Sheldon