Date   
Re: Bitx ver 3b/3c Linear power supply 40 meters

John Backo
 

This is L2. Yes, it is a toroid wound coil.

It is referred to on p.8 of the BITX v.3B complete assembly manual. It is part of a Pi network feeding the gate of the IRF510 to better balance the impedance needs. This is seen in the schematic of the PA. The original idea came form Farhan in a new design for a power amplifier, which is also in the files section.


john
AD5YE


---In BITX20@..., <ka2rrz@...> wrote :

Yes vers 3b /3c power supply pcb he small one with the irf520


On Wednesday, January 11, 2017 4:34 PM, "iam74@... [BITX20]" <BITX20@...> wrote:

Which BITX pcb are you referring to? I think you were working with the v3.B from Sunil.
What is the reference designator?


john
AD5YE

Re: Bitx ver 3b/3c Linear power supply 40 meters

Ron Hayes
 

ok thank you. I guess I am the only builder of this like the Bingo pcb I got last year? anyhow this was reassuring.


On Wednesday, January 11, 2017 6:49 PM, "jgaffke@... [BITX20]" wrote:


 
I have no idea what this "E-bay meter" thingie is.
Regardless, even if it was supposed to accurately measure an inductance that's down in the nano-Henry's, I'd have a lot more faith in the torroid charts.

Here's a chart that says 0.55uH would be more like 11 turns on a T50-2:
  
Jerry, KE7ER
 

---In BITX20@..., wrote :
Near the bottom of the pcb is a .55uh inductor, I don't have one and went on Toroid King site and claims T50-2 9 turns. My E-bay meter shows it as a resistor. Should I just go with the t50-2  9 turns?


BITX40 mod for better audio and a lesser hiss!

 

The Q15 collector voltage is a bit low to handle loud signals. I changed R114 to 180K and
added another 180K from Base to Emitter. This increases the collector voltage from around
1 Volt to about 3V. The hiss reduces a bit due to the change in time constant of R114 and
C118. You can add a parallel cap of another 100 or 150pf to roll off highs above 3 KHz.

Now the audio is better and more mellow in my BITX40 #63 with analog VFO.

73

--
Raj, vu2zap
Bengaluru, South India.

Re: groups.io Not Working

William R Maxwell
 

Maybe you jumped the gun. I thought we were awaiting advice from Hans and Fahan that it was all set to go?

Bill, VK7MX


On 12/01/2017 11:28 AM, kg4rul@... [BITX20] wrote:
 

I signed up and got the initial confirmation EMail and replied to the EMAIL as requested.  I can log onto the groups.io site but get this message for for Bitx and QPRLabs and groups:


Your account is not confirmed. You will not be able to participate in any groups until your account is confirmed.  Send another confirmation email.


I click on the message to have another confirming EMail sent and nothing shows up.


What am I missing here?


Re: Bitx ver 3b/3c Linear power supply 40 meters

Jerry Gaffke
 

I have no idea what this "E-bay meter" thingie is.
Regardless, even if it was supposed to accurately measure an inductance that's down in the nano-Henry's, I'd have a lot more faith in the torroid charts.

Here's a chart that says 0.55uH would be more like 11 turns on a T50-2:
  
Jerry, KE7ER
 

---In BITX20@..., <ka2rrz@...> wrote :

Near the bottom of the pcb is a .55uh inductor, I don't have one and went on Toroid King site and claims T50-2 9 turns. My E-bay meter shows it as a resistor. Should I just go with the t50-2  9 turns?

groups.io Not Working

Dennis Zabawa
 

I signed up and got the initial confirmation EMail and replied to the EMAIL as requested.  I can log onto the groups.io site but get this message for for Bitx and QPRLabs and groups:


Your account is not confirmed. You will not be able to participate in any groups until your account is confirmed.  Send another confirmation email.


I click on the message to have another confirming EMail sent and nothing shows up.


What am I missing here?

Re: Bitx ver 3b/3c Linear power supply 40 meters

Ron Hayes
 

Yes vers 3b /3c power supply pcb he small one with the irf520


On Wednesday, January 11, 2017 4:34 PM, "iam74@... [BITX20]" wrote:


 

Which BITX pcb are you referring to? I think you were working with the v3.B from Sunil.
What is the reference designator?


john
AD5YE


---In BITX20@..., wrote :

Near the bottom of the pcb is a .55uh inductor, I don't have one and went on Toroid King site and claims T50-2 9 turns. My E-bay meter shows it as a resistor. Should I just go with the t50-2  9 turns?


Re: Further impressions of the Raduino.

John Backo
 

You are probably right. This is common with the first version of many things. Now the question is: What would you do to improve things?

It's likely that the noise is the major source of your problems. The rig acts pretty good with a VFO (and maybe some other DDS).How does one isolate and eliminate it?

It's likely that faulty input on the pot connection is making the response flaky. How would you stop it?
(Probably with a damping capacitor).

How can the CW be improved? Would it take a shaping circuit? Could the audio be improved?

Etc.

john
AD5YE


---In BITX20@..., <special@...> wrote :

Well I'm sad to say that my third BITX40 is very unimpressive compared to the first two that I got.


First off I've needed to work on the audio stage as it was horribly unstable, even worse than most LM386 circuits and needed a couple of extra decouplings fitted.


Secondly I am sad to say that the Raduino DDS really is very poor.

It's noisy RF-wise (as I have mentioned in another post), is unstable and tends to run away with itself when you're trying to tune down the band. I also noticed that the tuning pot is sensitive to vibrations when you have managed to tune it in and will jump off frequency.


I managed to improve the RF radiated noise by not powering the board via the fitted 7805 device but (rather naughtily) supplying 5V via the micro usb port straight into the NANO.


The noise on the 5V rail when using the on-board 7805 was excessively high, coming I assume from the LCD and / or the Atmega328 chip switching and getting onto the supply rail. Lots of very nasty noise spikes could be seen on a scope, spiking at around 600mV. Adding some extra decoupling around the board helped but a separate supply was far and above superior.


Also I found that the Raduino simply isn't stable (another problem of the noise I suspect). It was ok listening to SSB but made CW sound very chirpy.


I also found that, when tuned it it would suddenly decide to step off down the band until it reached the band edge where it would stop. I haven't found a cure for that yet.


I'll be interested to see if anyone else has had these problems and if they've managed to deal with it.


As a precaution I also suggest checking the kludge on the 5 pin connector on the Raduino board.

On the one I got, a mistake on the board has simply been cut through with a knife and I found mine had not been done particularly cleanly. There was a real risk of a short occurring straight across the power rails due to copper whiskers left there..


73


Slim G4IPZ


Re: Bitx ver 3b/3c Linear power supply 40 meters

John Backo
 


Which BITX pcb are you referring to? I think you were working with the v3.B from Sunil.
What is the reference designator?


john
AD5YE


---In BITX20@..., <ka2rrz@...> wrote :

Near the bottom of the pcb is a .55uh inductor, I don't have one and went on Toroid King site and claims T50-2 9 turns. My E-bay meter shows it as a resistor. Should I just go with the t50-2  9 turns?

Further impressions of the Raduino.

special@...
 

Well I'm sad to say that my third BITX40 is very unimpressive compared to the first two that I got.


First off I've needed to work on the audio stage as it was horribly unstable, even worse than most LM386 circuits and needed a couple of extra decouplings fitted.


Secondly I am sad to say that the Raduino DDS really is very poor.

It's noisy RF-wise (as I have mentioned in another post), is unstable and tends to run away with itself when you're trying to tune down the band. I also noticed that the tuning pot is sensitive to vibrations when you have managed to tune it in and will jump off frequency.


I managed to improve the RF radiated noise by not powering the board via the fitted 7805 device but (rather naughtily) supplying 5V via the micro usb port straight into the NANO.


The noise on the 5V rail when using the on-board 7805 was excessively high, coming I assume from the LCD and / or the Atmega328 chip switching and getting onto the supply rail. Lots of very nasty noise spikes could be seen on a scope, spiking at around 600mV. Adding some extra decoupling around the board helped but a separate supply was far and above superior.


Also I found that the Raduino simply isn't stable (another problem of the noise I suspect). It was ok listening to SSB but made CW sound very chirpy.


I also found that, when tuned it it would suddenly decide to step off down the band until it reached the band edge where it would stop. I haven't found a cure for that yet.


I'll be interested to see if anyone else has had these problems and if they've managed to deal with it.


As a precaution I also suggest checking the kludge on the 5 pin connector on the Raduino board.

On the one I got, a mistake on the board has simply been cut through with a knife and I found mine had not been done particularly cleanly. There was a real risk of a short occurring straight across the power rails due to copper whiskers left there..


73


Slim G4IPZ


Re: Rarduino WAY off Freq

Mike
 

Farhan,

Yes I agree. But my Rarduino is putting out a much higher frequency. I have confirmed this with a scope and a radio. What would cause the frequency to be off that much? Can the sketch be corrupt? Do I need to ground the brown wire and try to move it 2 MHZ?

Thank you

Mike WA3O

Re: Rarduino WAY off Freq

Cory Clemmer
 

Is there a way to use my oscilloscope to measure the IF and then hardcore that into the atmega mcu?

On Jan 11, 2017 3:21 PM, "Ashhar Farhan farhanbox@... [BITX20]" <BITX20@...> wrote:
 

the vfo should run from 4.5 Mhz to 5.005 Mhz. At 5.005 MHz VFO, the RF frequency will be 12-5.005 = 6.995. At 4.5 MHz VFO, the RF frequency will be 12-4.5 = 7.5 MHz. 12 Mhz is the nominal IF frequency.

- f

On Thu, Jan 12, 2017 at 12:01 AM, mikeymustang2000@... [BITX20] <BITX20@...> wrote:
 

Group,
For some reason my Rarduino is way off frequency. ..6.1mhz at a display of 7.100 into a scope by itself...what an I doing wrong?

Thanks

Mike WA3O


Re: My BITX40 build

steve.shorey@...
 

I took a 100n cap in series with a 10k preset pot..and connected from the top (Red) connection of the volume control to ground..twiddled it to drop some of the treble off. The simplest tone control

Steve G3ZPS

Sent from Windows Mail

From: johnlinux77@... [BITX20]
Sent: ‎Wednesday‎, ‎11‎ ‎January‎ ‎2017 ‎20‎:‎07
To: johnlinux77@... [BITX20]

 

"The damn hiss was still present, and my simple but very effective solution was to roll off the audio response a bit with 100n and 10k preset across the volume control – very mellow sound now."


could you post a picture of this?
tnx


Re: Powering the BitX40 for portable use: votlages and battery chemistry

John VA7JBE
 

Thanks everybody for the helpful information!  I'm sure this will be quite useful as I build out my BitX40 into a lightweight portable unit. 

In regards to Sandeeps suggestion of using a 2SC1969 or RD16HHF1, would I be able to simply "drop in" these transistors to replace the IRF510 or would there be some additional adjustment necessary? 

Back when I was thinking about getting a KN-Q7A I found a final PA modification that used two RD16HHF1 chips as a class AB amplifier that would put out 20W with good linearity and little heat.  It was based on a design by Loftur Jonasson (TF3LJ/VE2LJX) and I'm wondering if it might make a more robust final stage for the BitX40.  It would also allow for 20W output at 13.8v. 

Based on the mods made by VK3IL, I'm also considering an LM2940-8.0 regulator and power schottkey diode for RX and a bypass to the final PA.  This would hopefully take a lot of strain off the regulator on the Raduino and moving the lowest supply voltage down to 8.5v, well within the ability of a 3S lithium ion or 4S LiFePoly battery.

Loftur Jonasson amp schematic and PCB
https://sites.google.com/site/lofturj/softrock6_3#TOC-Project:---HF-Power-amplifier-20W-using-2x-RD16HHF1-Mosfet.

VK3IL amp for KN-Q7A, with a very compact PCB including LPF for 40m
KN-Q7A mods

 

Re: Rarduino WAY off Freq

Ashhar Farhan
 

the vfo should run from 4.5 Mhz to 5.005 Mhz. At 5.005 MHz VFO, the RF frequency will be 12-5.005 = 6.995. At 4.5 MHz VFO, the RF frequency will be 12-4.5 = 7.5 MHz. 12 Mhz is the nominal IF frequency.

- f

On Thu, Jan 12, 2017 at 12:01 AM, mikeymustang2000@... [BITX20] <BITX20@...> wrote:
 

Group,
For some reason my Rarduino is way off frequency. ..6.1mhz at a display of 7.100 into a scope by itself...what an I doing wrong?

Thanks

Mike WA3O


Re: My BITX40 build

ohwenzelph
 

"The damn hiss was still present, and my simple but very effective solution was to roll off the audio response a bit with 100n and 10k preset across the volume control – very mellow sound now."

could you post a picture of this?
tnx

Bitx ver 3b/3c Linear power supply 40 meters

Ron Hayes
 

Near the bottom of the pcb is a .55uh inductor, I don't have one and went on Toroid King site and claims T50-2 9 turns. My E-bay meter shows it as a resistor. Should I just go with the t50-2  9 turns?

Rarduino WAY off Freq

Mike
 

Group,
For some reason my Rarduino is way off frequency. ..6.1mhz at a display of 7.100 into a scope by itself...what an I doing wrong?

Thanks

Mike WA3O

Las Vegas Ham Convention

Gary Desler
 

The second annual ARRL sponsored Nevada Amateur Radio Convention will be held March 31st through April 2nd.

We are looking for Bitx speakers to join an already impressive list. Please contact me if interested in speaking 

 

(Gary Desler AA7YO gdesler@me dot com)

 

. For those who wish to come you can register at 

Nevada State Convention  


Re: groups.io - was BITX 40 Questions

Jack Purdum <econjack@...>
 

Thanks, Hans. I think all of us appreciate your efforts to enhance the utility of this site...it's a treasure-trove for all of us.

Jack, W8TEE



From: "Hans Summers hans.summers@... [BITX20]"
To: BITX20@...
Sent: Wednesday, January 11, 2017 3:55 AM
Subject: [BITX20] Re: groups.io - was BITX 40 Questions

 
All

Farhan and I discussed it. As a result, I will move this YahooGroups BITX20 group to a groups.io BITX20 group. You do not need to do anything now. All members will automatically be moved across, and all files, folders, photos, archived messages, etc. All your preferences such as whether you receive every email, no email, or digest email, will also be preserved during the copy. It will take a day or two. I will inform the list when it is done

Thanks

73 Hans G0UPL