The Bitx40
What comes in the box
*4-1/2 inches by 5 inches tested SSB transceiver module, covering any 400 KHz segment of the 7 MHz band
*The Raduino board with Si5351, Arduino Nano with code loaded. Fully tested
*High quality BNC connector for the antenna
*Small electret microphone
*Two earphone-style audio jacks for the mic and the earphones/speaker
*A set of DC power socket and plug
*Volume control with on/off switch
*10k linear pot for tuning
*8 brass standoffs with mounting nuts and bolts
*Connectors with wires for all connections to the board
The Bitx40 has been covered all over by now, I will skip the intro and move onto some of the mods and building ideas. Anyone that is new to the Bitx40 should see HFSignals website for full detials.
AGC
The 1st mod I did was AGC, which I got from DuWayne KV4QB. His blog was a big help for this and have been able to get some pcb's from DirtyPCBS. The AGC works but after a few months trying out psk and other modes I found a on/off switch was useful.
The 1st mod I did was AGC, which I got from DuWayne KV4QB. His blog was a big help for this and have been able to get some pcb's from DirtyPCBS. The AGC works but after a few months trying out psk and other modes I found a on/off switch was useful.
Filters!
One filter I found by chance looking around online was, New England QRP clubs Nescaf. This filter is great for the qrp CW ops out there. The board you see under all the wires to the right is the nescaf board. It was easy to add to the audio stage, just be sure to add it as late in the audio chain as you can to avoid issues. I have placed this after the AGC in the audio chain.
The NEQRP group has great build notes which are easy to follow. I like this filter so much I have 3 of them! Great news is they are kitting the Nescaf again after many years of looking for kits at swaps.
One filter I found by chance looking around online was, New England QRP clubs Nescaf. This filter is great for the qrp CW ops out there. The board you see under all the wires to the right is the nescaf board. It was easy to add to the audio stage, just be sure to add it as late in the audio chain as you can to avoid issues. I have placed this after the AGC in the audio chain.
The NEQRP group has great build notes which are easy to follow. I like this filter so much I have 3 of them! Great news is they are kitting the Nescaf again after many years of looking for kits at swaps.
Zero beating
As I one day aspire to be a good CW op I added a zero beat led indicator, activated via a button to the lower left of the main tune knob (yellow led).
This is based off the LM567 tone detector, many diagrams and versions can ge found with a quick google search. I have also had luck with a small kit from ebay. In all forms its pretty basic, all you really have to choose/set is the center Freq at which the led will peak. I have noticed when setting the center freq its best to go back and forth from the top and bottom of the zeroed in signal to get a nice center setting. Any form of known tone generation will work be it computer, keyer or radio.
The newer bitx40 firmware has a zero beat funtion added. This allows fine tuning as well as sidetone for zeroing in with audio tone. I have commented out the portion of code that generates the tone. I just use the zero beat button for fine tuning.
As I one day aspire to be a good CW op I added a zero beat led indicator, activated via a button to the lower left of the main tune knob (yellow led).
This is based off the LM567 tone detector, many diagrams and versions can ge found with a quick google search. I have also had luck with a small kit from ebay. In all forms its pretty basic, all you really have to choose/set is the center Freq at which the led will peak. I have noticed when setting the center freq its best to go back and forth from the top and bottom of the zeroed in signal to get a nice center setting. Any form of known tone generation will work be it computer, keyer or radio.
The newer bitx40 firmware has a zero beat funtion added. This allows fine tuning as well as sidetone for zeroing in with audio tone. I have commented out the portion of code that generates the tone. I just use the zero beat button for fine tuning.
Keyer
Another Option I added that was later updated in firmware was a keyer.
The keyer I used was a V1 Mini keyer from QRPguys.com. Easy build and very simple to add to the bitx40. Has macros and command options via push buttons.
Another Option I added that was later updated in firmware was a keyer.
The keyer I used was a V1 Mini keyer from QRPguys.com. Easy build and very simple to add to the bitx40. Has macros and command options via push buttons.
Misc Mods
I have played with some other hardware mods here are a few.
Biggest mod that is a must! for U.S. operators is the LPF mod. This mod should be done very early in your build and is very simple. Add a 100pf Cap across L7 and you will be legal.
Another hack I have played with is VK3YE's great video on the bitx40's audio. Be sure to re-align the radio after this mod.
I have played with some other hardware mods here are a few.
Biggest mod that is a must! for U.S. operators is the LPF mod. This mod should be done very early in your build and is very simple. Add a 100pf Cap across L7 and you will be legal.
Another hack I have played with is VK3YE's great video on the bitx40's audio. Be sure to re-align the radio after this mod.
New Mic
I did not like the audio on the stock mic element and have since replaced it with a JLI-52B from JLI Electronics.
Sounds much better to me.
I did not like the audio on the stock mic element and have since replaced it with a JLI-52B from JLI Electronics.
Sounds much better to me.
I have had a great time building and operating my Bitx40. I look forward to the newest in the line of Bitx radios the Ubitx now in pre-order as of 12/12/17. Check out HFsignals for more info!