Join us as we make contacts from BITX40 to BITX40 on 7.277 MHz in 40 meters!

This is a worldwide event for BITX40 stations starting at 7pm in each time zone. To participate, call CQ BITX on Sunday, starting at 7pm your local time. The BITX QSO Night continues through the evening and conditions usually improve after sunset, so it is worthwhile to participate later in the evening.

Suggested Best Operating Practices:

Work at QRP power levels unless conditions require more power.
Call and listen for CQ BITX on the hour and every quarter hour.
It is helpful if you call CQ BITX with your callsign, name and location.?
Repeat your callsign a number of times during your CQ BITX and during QSO's.
Start a QSO by confirming the callsign, location, name and signal report of the other operator.
Say the callsign, name and location of the other operator so others can hear.
If the frequency is busy, avoid long conversations.
After your initial QSO is complete, ask if there are any other stations who would like to contact.

Report your QSO's, discuss propagation, noise, signal reports, audio reports, antenna type, etc. in this thread.

This is an undirected, scheduled event.? The BITX QSO Night relies on you to call CQ BITX to initiate contacts with other stations, so warm up that final and transmit a few calls on Sunday evening.? Talk to you then!
--
John - WA2FZW

¿ªÔÆÌåÓý

I have purchased this kit from EA3CGY, which is intended to mend this problem... have a look at it
?
?

systems like that will cover? over the issue --- but adding delay can make your system less able to participate in ARQ error correction system that need fast switchovers (a key goal for ARES usage in my group)

Instead of covering it over, fixing it by discharging the filter capacitors faster through a simple transistor switch driven by the rising TX power line will reduce/eliminate the voice-through.? ? Regardless, the system as built functions well with error corrected WINMOR protocol.

but if voice isyour only interest, the suggested system should work well for you.

Hi Rob,
C14 is a 100uF electrolytic cap.?

Good luck and 73,

Loren

¿ªÔÆÌåÓý

"I am experiencing this annoying thing when I PTT.?When I speak my voice can be heard through the rig speaker. It is only for 1sec maybe less.?
Anyone experiencing this??"

It is a normal thing.? ?The capacitors on the last and next-to-last audio stages are able to drive the audio amplifier for 1-2 seconds, and perhaps through +V modulation, they pick up whatyou are saying.??

There was a previous modification suggested but I didn't quite understand it.? ?I have tested simply having a 2N3904 through a 470 or 1000 ohm resistor pull the last audio amplifier capacitor down; the 2n3904being driven by 10K from the +TX power line.? ?This significantly shortened the time the audio amp remained "on".? ? I haven't yet written it up, am working on a small audio preamp printed circuit board that will also include this little transistor switch as well.? ? Am hoping to use the Bitx40 to help members of my ARES group get on HF so working on little mods.? ?

Gordon

With RV1 fully clockwise, the FET's current *will* be 0. With power off, practice turning RV1 anti-clock to get about 10 seconds end-to-end. Back to fully clockwise, power up and turn anti again as before. Around mid-way the current will increase. I'd recommend the 2A range for starters, and go as far as 0.1A - no further. Then go to the 200mA range and 'fine tune'. It's touchy!

73, ZL2DEX

I'm thinking my problem is either at the very beginning of the transmitter section, or at the very end.
While checking voltages all throughout (yeah I don't know what all of them are suppose to be but you'd think there should be something) I found the voltage directly before capacitors 155 and 156 to be the same as my power supply. On the other end of these capacitors I found it to be in the milliamps regardless of transmitting status. I figure this is either because something is wrong here...or maybe on the other end of the transmitter section.

OK, education time. The diagram has red bits as components connected (by track or wire) by green lines. Label 'flags' go to other parts of the diagram, continuing the connection/s. As such, PA-PWR (DC? Volts) goes through L8 and primary of T7 (it can't go through C 153 or 154 - DC cannot pass through a capacitor - only the effect of changing voltage - i.e. AC - can do that) - so it continues to and through one of the secondary windings to C155-C156. It can't go any further, so the other side is *by definition* at 0V (Volts! DC!) at all times. Back to basics.

73 de ZL2DEX

VA3NOI

Hi Loren - I am currently building the B40 but I am a few days behind you (looking at the pace of my building and my projection of free time). If you don't mind, I have a quick question for you.?

I noticed that there is a place for a capacitor (C14) on the board but there is no mention of C14 in the bill of materials, or on the schematic or in any of the other documentation. There is an electrolytic capacitor shown in one? photos and it looks like it simply connects from the the DC source to ground to dampen any voltage fluctuations. Is that right? What value, if any, for C14 did you use??

I'll wait patiently until Jack returns from vacation to hear about the rotary encoder or I may try to figure it out in the meantime.?

Thanks and 73,
-Rob
N4MN

¿ªÔÆÌåÓý

Yes, you are on the right track.

I have built about16 RaduinoX PCB that a lot of folks here have purchased.

I had problems on AT LEAST 1/2 like you are describing.

It was always the Crystal or the SI531 part.? I use a Tiny little crystal that is tough to solder.

So, I now have a procedure.? Solder all the I2C circuitry down with its connector.

I have another RaduinoX? (Without SI5351 part) sending a test program at 10 MHz.

I get the I2C signals on the Scope looking like they should at the SI5351 part on the board I am testing.

Then I install the SI5351 part.? Sometimes it Kills the I2C.? I have seen I2C even on the Clock outputs.

I have seen open pins to the Clock or Crystal.

hi
my raduino doesn't work again, checked it with frequenzy counter on the outout signal, the frequenzy go up and down isn't stable.
infact the rtx don't work, to made a test i have used a rf generator into VFO input and the rtx start to give a good power out.
i think there is a problem on my raduino board.
the nano is able to program infact i download the last sketch for it.
do you think is the chip 5351 the problem?
thank you
73 Aurelio IZ8EGM

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

¿ªÔÆÌåÓý