The All-band HF Amateur Radio Transceiver: Just waiting to be modified
Jim Sheldon W0EB says, “Finally I have this one where it will get it’s top cover put on and the radio goes into the ‘go box’. “With the addition of one of our RadI2Cino cards, an I2C 4 line by 20 character display, a Teensy 3.6 adapted to plug in place of the NANO, this …
John VK2ETA has uploaded an updated folder to the BITX20 IO Group list files section. This adds new schematics for his Antenna Tuning Unit (ATU). ATU Design objective 1. Fits in the limited space of my Jameco case (Jaycar case here in Oz), on my second level board. 2. Tunes long wire and EFHW (worst …
Continue reading “VK2ETA automatic L-match using separate arduino nano”
Don ND6T has been tinkering with AGC mods, and has come up with a new solution that gives much high levels of RF compression. The µBITX presents some challenges with RF AGC system design: There is no RF preamplifier to use as a voltage-controlled attenuator, it is broadband and includes no tuned circuits in the …
Allison KB1GMX finds it odd that every one seems to be bent on levelling the audio volume in the audio circuit. The Bitx or uBitx has enough gain and handy places that RF gain control based on audio detection works very well. The easy way is replace R13 (ubitx) with a diode such as 1n400x …
Continue reading “Using a 1N4004 or similar as a varicap or pin diode for AGC control”
Don ND6T has recently installed a 20 dB RF AGC modification in the BITX40. He has not installed it in the uBITX yet but intends to do so soon. It’s a simple circuit and replaces the S meter circuitry, too. Most BITX automatic gain control schemes use the audio output to apply control of the …
There are a number of very talented people involved in modding the µBITx. A number of BITX20 IO group members have mods under way that we can look forward to hearing reports on in due course. This news item provides a bit of a round up of what’s in store for the µBITx constructor community. …
John VK2ETA has done a strait replacement of the IRF510s with RD16HHF1s in his uBITx. You can see from the photo above that he has them installed cross-legged. John says, “To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and …
Why should I use a BCI filter? The uBITx has a front end 0-30MHz band pass filter. If you live in an area where there are high power AM Medium Wave transmitters you are likely to suffer from Broadcast Interference (BCI). BCI typically appears worst on the 160m and 80m bands, but as a result …