Keyboard Shortcuts
Likes
Search
Bitx40 on 20 m
|
Now that I have the bitx working again with the arduino, I built an off board BPF for 20m. Using VFO - BFO (25.998600 MHZ -?11.998600 MHZ), the VFO is greatly attenuated when it reaches T2. All I'm getting is 700 mv p-p. I am assuming that the Q7 to Q9 circuitry is attenuating it. Maybe C91 and C92 have something to do with it. I will investigate. Guess I can try switching to VFO + BFO to check. I will post my results. 73 Ken VA3ABN |
|
remove the two caps and try. - f On 27-Jan-2017 3:54 am, "Ken" <chase8043@...> wrote:
|
|
next thing I will do 73 Ken On Thu, Jan 26, 2017 at 9:30 PM, Ashhar Farhan <farhanbox@...> wrote:
|
|
Did you get this figured out?...I did the same by replacing the band pass and low pass for 20 meters...when the VFO is set for 2 MHZ I get RX on 20 but on LSB...So I move the VFO to 26 Mhz and I get no RX. So I am betting the ?VFO amp is not working at 26 MHZ. I realize I can move the IF frequency to above 12MHz... Thank you Mike WA3O |
|
If using the same VFO frequency range as in 40m, shouldn't it be 19 not 26. 19 MHZ - 5 MHZ = 14 MHZ. 73 Ken VA3ABN On Tue, Mar 28, 2017 at 4:24 PM, Mike via Groups.Io <mikeymustang2000@...> wrote:
|
|
OOPS, wrong numbers. 12 MHZ + 14 MHZ = 26 MHZ 73 Ken On Tue, Mar 28, 2017 at 4:35 PM, Ken <chase8043@...> wrote:
|
|
Great Mike, thanks a lot. I am adding 80m to mine with a QRP Labs 80m BPF, but I'm interested in adding 20m as well. Once I get the 80m BPF in it won't be hard to add a 20, and I can use my same method to add a 20m LPF I think. I'm interested in how you're switching them out. Also, does removing?C91 and C92 affect LSB operation? If not, then it's just a matter of removing those, switching filters, and getting the VFO to automatically change offsets, I think!?
-- Ryan Flowers KC7RYS? |
|
?OK I removed C91and C92 and the BitX40 now receives and transmits on 20 meters on USB using the 26.180mhz -11.995mhz ~14.180. Ken you where correct! ?Ryan I have the pics you asked for but with the storage constraints on the forum in am not sure I should upload them? Is there an email I can send them to? Thanks to all that helped! 73s Mike WA3O |
|
Mike May I see them as well? My email is this one for the group. 73 Ken VA3ABN On Wed, Mar 29, 2017 at 4:42 PM, Mike via Groups.Io <mikeymustang2000@...> wrote:
|
|
Mike, An easier fix would be to increase the VFO signal by the raduino software, using the "drive_strength" command. Just add the following line to the setup() routine: si5351.drive_strength(SI5351_CLK2, SI5351_DRIVE_8MA); The drive strength is the amount of current into a 50¦¸ load. 2 mA roughly corresponds to 3 dBm output and 8 mA is approximately 10 dBm output. I believe the default is 2mA, and you can increase it to max 8mA. This is probably sufficient to compensate for the attenuation of the two caps. 73, Allard PE1NWL |
|
Mike Thanks for the pics. Nice job on the Bitx. Those are QRPLabs filters? 73 Ken VA3ABN On Wed, Mar 29, 2017 at 6:00 PM, Mike via Groups.Io <mikeymustang2000@...> wrote:
|
|
Hey Mike, Thanks for the pix. Looks like QRP Labs filters to me- The stock LPF should work for 80 and 60m, so I don't plan on replacing that. I see that you've made it so that you can plug in any filter set, which is very cool! Mine will simply switch out the 40/80m BPF's with less board surgery. When it comes time to go 20m, more work will need to be done for sure. -- |
|
Mvs Sarma
Raduino know whether 300¡ã pot or 10 turn pot.? Firmware, perhaps looks for the resistance at that moment and the takes action. ?for experimentation on raduino you can always have a new mega328 and load with same file or do mods etc ?original would be in safe custody> On Thursday, 30 March 2017 11:20 AM, Ryan Flowers <geocrasher@...> wrote: Hey Mike, Thanks for the pix. Looks like QRP Labs filters to me- The stock LPF should work for 80 and 60m, so I don't plan on replacing that. I see that you've made it so that you can plug in any filter set, which is very cool! Mine will simply switch out the 40/80m BPF's with less board surgery. When it comes time to go 20m, more work will need to be done for sure. -- Ryan Flowers KC7RYS? |
Allard PE1NWL