Date   
R141 fried

Michael Davis <maddmd818@...>
 

Well, after months of trouble free, fairly infrequent operating, I did something to burn out R141. After replacing it with a small axial resistor, it worked into a QRP dummy load, but when I connected it to my ground mounted vertical antenna, I smoked the axial too. Stinky smoke. My dummy load is the Elecraft copy so I can read voltage on the graph they publish and convert it to power. I did this while using my cell phone audio frequency app against the mic. 11 volts is about 6 watts. Of course, a steady audio tone may be too much power for the final to handle. I guess I should use my tuner, or use my QRP, 40 meter antenna and no others. What mismatch can the Bitx40 handle? Should I reduce power out by lowering the drive by adjusting r136? Any other thoughts? Thanks

Re: SMD Group Build

Clark Martin
 


Clark Martin
KK6ISP

On Jan 24, 2018, at 5:56 PM, Diver Martin <diver.martin@...> wrote:

Mouser & Digikey are my go-to for SMT parts.  They carry just about everything.  If you have other oddball SMT stuff, and either one are out, head to findchips.com.  There are alternate suppliers, but those two always have what I need, either in the exact specified part number, or an equivalent.  Other places will source 1206's and stuff, but might only sell by the full reel (which I have yet to need, except maybe 0.01uF caps or 0.1uF caps across multiple, multiple projects).

SMD resistors/caps (0603, 5% in my case) are usually cheap enough that I buy them in 1000-piece quantity, because $2 of parts for life or $0.5 for the parts I need for the project, and to always have them on hand, is easy.


I’ve only bought from Digikey a few times but I use Mouser all the time.  Also there are Newark and Allied for such supplies.

I bought a set of 0805 resistors (from 0 ohm through several Mohms) and a set of 0805 caps (10s of pF through 1µF).  They came on cards that fit a day planner binder.  There are between 1 and four strips of 25 each for each value (depending on expected usage levels).  I have little trouble working with 0805 parts and they  fit nicely on .1” grid perfboard (with plated through holes).  

When I use up a strip I buy a new strip of 25 at a local electronics shop (Silicon Valley still has a few).

I haven’t done any PCB fabricating yet but that is in the plans.

SMD diodes and transistors of most any size are easily soldered to perfboard.

I’ve also soldered up to 8 pin SOICss buy putting alternate pins on the perfboard pads and tack soldering leads to the other pins.

It definitely makes for smaller boards.

Re: SMD Group Build

 

This is how I DIY SMT....
https://hackaday.io/project/7938-pcb-smt-maker-lab-home
--
AncelB, MIT EE6002

Re: Software support Request for Full QSK BITX40

Gary O'Neil
 

... that are masked by the Purging Switch in previous post...   

Thank Apple for the #%~? discontinuity in this post.

With the caveats above, and others to be discovered, proceed at your own risk/reward comfort level. Attached are the remaining mods... requires removal of K1 & K2, and some jumpers at K2 to short pins 3 & 5, and pins 12, 14, & 16. 

All 3 circuits interface to the K1 pads. Any layout volunteers interested in doing a layout of a daughter board that plugs into a 16 Pin DIP header at K1 for this? It doesn’t look like I’m going to learn Kicad this vacation trip. :-(

72/73

Gary, N3GO

P.S.  My apologies for the slow response time and bungled posts. I’ve been barely dangling from the grid this trip.  dit dit !!!

Re: AE7EU Top Level PCB Mod

Diver Martin <diver.martin@...>
 

Geoff, I'm not sure Farhan wants to.  If he wants to, I'm sure he'd approach people with respect to that.  But I've gotten the indication that they're more about encouraging others to set up their own shops for manufacturing.  I won't put words in his mouth, but he may have discovered how time and soul consuming it is to sell a product like this :)

On Wed, Jan 24, 2018 at 6:04 PM, Geoff Lowe <gdlemail@...> wrote:
Aren't we missing the obvious solution for manufacture? Don't we already know someone who is all set up to do this? I'm thinking this might be a nice add-on for Farhan's group to do. They do SMT soldering, torpid winding, etc. Maybe he would be willing to add this to his manufacturing group? Just thinking out loud here . . . 




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?

Re: BitX40 voltage booster implementation

AA9GG
 

Specs say the part runs at a fixed 100khz.  The LM2587 seems to be a nice part.  Mouser wants $8 a piece, so module is a sweet deal!

On Wed, Jan 24, 2018 at 6:46 PM, Michael Davis <maddmd818@...> wrote:
In my experience, the boosters are very noisy. They are sort of inverters.

Sent from Mike's iPad WA1MAD









--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com
NAQCC 3123, SKCC 4628

Re: Software support Request for Full QSK BITX40

Gordon Gibby <ggibby@...>
 

​Are those ONE microfarad capacitors in the input and output of the series mosfet doing the T/R switching?   Seems sorta large....or is there a decimal point that I can't see and they are really supposed to be 0.1 microfarad????


Thanks....


gordon gibby



From: BITX20@groups.io <BITX20@groups.io> on behalf of Gary O'Neil <n3go@...>
Sent: Wednesday, January 24, 2018 9:27 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Software support Request for Full QSK BITX40
 
... that are masked by the Purging Switch in previous post...   

Thank Apple for the #%~? discontinuity in this post.

With the caveats above, and others to be discovered, proceed at your own risk/reward comfort level. Attached are the remaining mods... requires removal of K1 & K2, and some jumpers at K2 to short pins 3 & 5, and pins 12, 14, & 16. 

All 3 circuits interface to the K1 pads. Any layout volunteers interested in doing a layout of a daughter board that plugs into a 16 Pin DIP header at K1 for this? It doesn’t look like I’m going to learn Kicad this vacation trip. :-(

72/73

Gary, N3GO

P.S.  My apologies for the slow response time and bungled posts. I’ve been barely dangling from the grid this trip.  dit dit !!!

Re: R141

 

The transistor Q14 is probably bad. Check R142 and 143 if both are ok then replace Q14.

I have observed on a FLIR thermal imager that R143 gets real hot and heats up the whole
area on the PCB. This probably degrades other parts around it.

Raj


At 25/01/2018, you wrote:
Replace it with a 1/2 watt.  Also make sure the transistor is not bad.
There have been many discussions about this resistor.  The original part is a 1/4 watt but should be higher.

Hope this helps,

Marco - KG5PRTÂ

On Jan 24, 2018 6:53 PM, "Michael Davis" <maddmd818@...> wrote:
Well, after doing many tests and staring at the tiny components for much too long, I finally noticed, with help from this forum, that R141 was in fact burned open. I believe that I must have transmitted into a non resonant load and smoked it, or set bias or drive too high. What are the wattage values of SMD resistors? I'll replaced it with an axial 1/8 watt 10 ohm. It to started to smoke. One step forward and 2 steps back...but getting there. Is anyone using a QRP tuner? Are you doing this to protect the Bitx PA? 73

Sent from Mike's iPad WA1MAD

Re: More digital lines on the Raduino..

AA9GG
 

The 8574 I2C expander is a nice part. Good idea.  Only a 2 byte write, so lag time shouldn't be a problem

On Wed, Jan 24, 2018 at 10:28 AM, Dennis Zabawa <kg4rul@...> wrote:
With an I2C expander, the TX_A, TX_B, TX_C and CW_TONE lines could be implemented freeing up 4 digital I/O lines.




--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com
NAQCC 3123, SKCC 4628

Re: BitX40 voltage booster implementation

Vic WA4THR
 

The input and output negative leads are connected in this unit. I might be able to power it off the 12v TX line, so it would not be powered on receive, but that might be too much current from that circuit. I'll have to test to see if it adds noise or hash on transmit, but was curious if anyone else had implemented this.

=Vic=

Re: BitX40 voltage booster implementation

AA9GG
 

I believe the 12v part will do 1A on the output, where the 5v part is limited to 300mA

On Wed, Jan 24, 2018 at 9:22 PM, Vic WA4THR via Groups.Io <vhklein@...> wrote:
The input and output negative leads are connected in this unit. I might be able to power it off the 12v TX line, so it would not be powered on receive, but that might be too much current from that circuit. I'll have to test to see if it adds noise or hash on transmit, but was curious if anyone else had implemented this.

=Vic=




--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com
NAQCC 3123, SKCC 4628

Re: Software support Request for Full QSK BITX40

Jerry Gaffke
 

I like what you're doing, hope it works.
A few potential issues to think about if you haven't already:

The receiver protection diodes may cause trouble on the uBitx:
    https://groups.io/g/BITX20/message/37380

I've seen TR switching done like that with series and shunt 2n7002's,
but not beyond the 5W level.

What impedance to received signals does the transmit final present?
Often TR switches at these power levels use a pin diode (or 1n4007) to isolate the transmit final.

When transmitting 10W, that's around 64v peak-to-peak of RF into 50 ohms, 
more if voltage to the IRF510's is raised above 12v, or the antenna is high impedance.
Vgs for a 2n7002 is +/- 20v max, has an intrinsic diode from source to drain.
I'm not sure exactly what will happen around those 2n7002's but would not bet they will survive.

The Bitx20 up on qrpkits.com is doing something vaguely similar in TR switching,
but they found reason to make it a considerably more complicated.

Jerry, KE7ER

Can uBITX be modified for AM Phone operation?

Nelson
 

I recently ordered a uBITX kit and from what I am reading it will be a while before I get it.  In the mean time I am reading the posts on this site and considering the type of box I want to mount it in etc. 

I do have a question.  Can the transceiver be modified for AM Phone operation?  If so what would be involved?  I have also ordered a 45 watt linear amplifier to use with the uBITX and perhaps with my FT-817ND  so a reduction in power by going to AM operation would not be so critical.

Thanks,

Nelson
KG7GYS

Re: Can uBITX be modified for AM Phone operation?

wb7dmx@att.net
 

why would you want too ?

Re: Can uBITX be modified for AM Phone operation?

Jerry Gaffke
 

AM Phone would require a significant redesign. 
Start by ripping out the 12mhz crystal filter at X1-8
and the balanced modulator at T7/D5
Have at it!

Jerry, KE7ER


On Wed, Jan 24, 2018 at 07:56 pm, Nelson wrote:
Can the transceiver be modified for AM Phone operation?  If so what would be involved?

Re: SMD Group Build

Jack, W8TEE
 

Thanks, I might give this a try.

Jack, W8TEE



From: Ancel <protofabtt@...>
To: BITX20@groups.io
Sent: Wednesday, January 24, 2018 9:19 PM
Subject: Re: [BITX20] SMD Group Build

This is how I DIY SMT....
https://hackaday.io/project/7938-pcb-smt-maker-lab-home
--
AncelB, MIT EE6002


Re: SMD Group Build

Jack, W8TEE
 

I can barely see a 0603! I would prefer 1206 if I can find them and am not too worried about the cost differential.
Jack, W8TEE


From: Clark Martin <kk6isp@...>
To: BITX20@groups.io
Sent: Wednesday, January 24, 2018 9:15 PM
Subject: Re: [BITX20] SMD Group Build


Clark Martin
KK6ISP

On Jan 24, 2018, at 5:56 PM, Diver Martin <diver.martin@...> wrote:

Mouser & Digikey are my go-to for SMT parts.  They carry just about everything.  If you have other oddball SMT stuff, and either one are out, head to findchips.com.  There are alternate suppliers, but those two always have what I need, either in the exact specified part number, or an equivalent.  Other places will source 1206's and stuff, but might only sell by the full reel (which I have yet to need, except maybe 0.01uF caps or 0.1uF caps across multiple, multiple projects).

SMD resistors/caps (0603, 5% in my case) are usually cheap enough that I buy them in 1000-piece quantity, because $2 of parts for life or $0.5 for the parts I need for the project, and to always have them on hand, is easy.


I’ve only bought from Digikey a few times but I use Mouser all the time.  Also there are Newark and Allied for such supplies.

I bought a set of 0805 resistors (from 0 ohm through several Mohms) and a set of 0805 caps (10s of pF through 1µF).  They came on cards that fit a day planner binder.  There are between 1 and four strips of 25 each for each value (depending on expected usage levels).  I have little trouble working with 0805 parts and they  fit nicely on .1” grid perfboard (with plated through holes).  

When I use up a strip I buy a new strip of 25 at a local electronics shop (Silicon Valley still has a few).

I haven’t done any PCB fabricating yet but that is in the plans.

SMD diodes and transistors of most any size are easily soldered to perfboard.

I’ve also soldered up to 8 pin SOICss buy putting alternate pins on the perfboard pads and tack soldering leads to the other pins.

It definitely makes for smaller boards.


Re: BitX40 voltage booster implementation

vk3xl@...
 

I use one of these in one of my BitX40s.
http://173.214.160.240/item/in-stock-MP9141ES-MP9141/32800753682.html?spm=0.search0305.3.53.619060867Nvj7u&ws_ab_test=searchweb0_0,searchweb201602_0_10130_10615_10617_10616_10618_10059_10534_10313_10084_100031_10083_10547_10624_10546_10623_441_10307_442_10548_10341_10065_10142_10340_10068_10343_10342_10103_10620_10344_10325_10545_10622_10324_10621,searchweb201603_0,ppcSwitch_0&algo_pvid=c90bd8e3-3705-43cd-980a-a810f9ce870c&algo_expid=c90bd8e3-3705-43cd-980a-a810f9ce870c-7
I have it set to 12V and it powers the main part of the circuit board and the raduino. The finals are powered separately but from a common DC connector. This allows me to power the rig from any voltage source from 12V to 28V  without having to make any internal adjustments. The Bucking converter does not introduce any noise that I can hear above the band noise on 40 meters as far as I can tell.

--
Mike VK3XL

Re: BitX40 voltage booster implementation

Clark Martin
 


Clark Martin
KK6ISP

On Jan 24, 2018, at 7:22 PM, Vic WA4THR via Groups.Io <vhklein@...> wrote:

The input and output negative leads are connected in this unit. I might be able to power it off the 12v TX line, so it would not be powered on receive, but that might be too much current from that circuit. I'll have to test to see if it adds noise or hash on transmit, but was curious if anyone else had implemented this.

Check the idle current, it might not be very much in which case there is little advantage to switching it on with TX.

Re: SMD Group Build

Jack, W8TEE
 

I think 0805 is about as small as we'd want to go. Man, one good sneeze with 0603's and the project's dead. Good to know about the PCB houses. Sounds like that's the way to go.

Jack, W8TEE



From: Diver Martin <diver.martin@...>
To: BITX20@groups.io
Sent: Wednesday, January 24, 2018 8:57 PM
Subject: Re: [BITX20] SMD Group Build

Hi Jack,

SMT board is the same as Through hole, no cost difference.  Some PCB manufactures will put a limit on the hole density, but it's usually gotta be something pretty high like 1000 holes/sqin (think perfboard).  As an example, OSHPark charges $5/sqin.  It doesn't matter if it's all SMT + vias, no vias no drills, or TH.  2 layers, $5/sqin as big as you want to go.  

Mouser & Digikey are my go-to for SMT parts.  They carry just about everything.  If you have other oddball SMT stuff, and either one are out, head to findchips.com.  There are alternate suppliers, but those two always have what I need, either in the exact specified part number, or an equivalent.  Other places will source 1206's and stuff, but might only sell by the full reel (which I have yet to need, except maybe 0.01uF caps or 0.1uF caps across multiple, multiple projects).

SMD resistors/caps (0603, 5% in my case) are usually cheap enough that I buy them in 1000-piece quantity, because $2 of parts for life or $0.5 for the parts I need for the project, and to always have them on hand, is easy.

On Wed, Jan 24, 2018 at 5:27 PM, Jack Purdum via Groups.Io <jjpurdum@...> wrote:
All:

We have a small group of local hams who enjoy building stuff, yet most are scared to death of SMD parts. Our last build had 29 do the build which is about half of our group. What I'd like to do is put together a small SMD project and have 30 or so boards made. (I have no idea what a good starter project would be.) If anyone has done this, are the board costs less than thru-holes boards? Also, are Mouser and Digikey the likely source for large (e.g., 1206) parts or do you know of a better source.

Thanks!

Jack, W8TEE



--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?