Date   

Re: JackAl BOM help pls

PeteWK8S <pmeier@...>
 

The 2x3 connector specified is an IDC connector not a plain pin header. Your suggested method can work but will not be as clean or easy to connect and disconnect as using IDC connectors as Jack is suggesting.

Thanks


Re: JackAl BOM help pls

MadRadioModder
 


The transformer is just a minature interstage isolation transformer.  600:600.   They are all over ebay. 

The 2x3 connector you can make by breaking off parts of a 1x40 easily. 

 


On Dec 27, 2018, at 11:43 AM, PeteWK8S via Groups.Io <pmeier@...> wrote:

Hi all, 
I've collecting parts for the upcoming JackAl PCB. Jack's BOM lists what we need but not where to find the parts.
 I've located most parts. However, I'm having a devil of time finding two parts. 

The two parts are:  6 Pin, dual row (2x3) IDC male and female connectors.    
                                Audio isolation transformers, 600 ohm, 1:1    - need correct size for the PCB - lots of different configurations of these out there.

Thanks for any help.

Pete WK8S
pmeier@...
                     

--

…_. _._


JackAl BOM help pls

PeteWK8S <pmeier@...>
 

Hi all, 
I've collecting parts for the upcoming JackAl PCB. Jack's BOM lists what we need but not where to find the parts.
 I've located most parts. However, I'm having a devil of time finding two parts. 

The two parts are:  6 Pin, dual row (2x3) IDC male and female connectors.    
                                Audio isolation transformers, 600 ohm, 1:1    - need correct size for the PCB - lots of different configurations of these out there.

Thanks for any help.

Pete WK8S
pmeier@...
                     


Re: uBITX for sale $67

Dave Dixon
 

hi bill,
       this is not meant to be a sob story but  Ive a friend who is disabled and confined to a wheelchair and if your bitx is still for sale would you be willing to post to the uk.? then i will box it for him.Regards Dave.G0AYD QTHR QRZ.COM


On Sun, 23 Dec 2018 at 17:23, Jon Titus, KZ1G <tituskz1g@...> wrote:
uBITX transceiver for sale.  I built the radio but didn't use it beyond a few quick CW QSOs.  Unfortunately it's unlikely I'll use it again.  Well packaged and shipped in the USA.  Transceiver and shipping via UPS or USPS, $67 total.  Documentation included.  Paypal only: jontitus@....  (See photos.)

This transceiver includes a 4-line LCD and programmed Arduino module for the RadI2Cino (Radio-I2C-Arduino) modifications.  (Documentation included.)  I installed this and it works.  This mod includes a different controller board, but you can revert to the original configuration if you wish.  I'll include the original plug-in control module, 2-line LCD, and the Arduino module so you can go back to the original configuration if you wish.

The transceiver comes mounted on a wooden board with clear plastic front and rear panels.  You can use the radio as-is or put it in a case of your choice.  Instead of using the pushbutton in the incremental encoder rotary control I added a separate high-quality pushbutton.  The RadI2Cino modification required a second pushbutton for the VFO selection (A/B/Split).

I removed the transmit/receive relay and replaced it with a front-panel switch.  Two small LEDs indicate the status (red-transmit and green, receive).  I'll include this relay in case you want to use it instead of the switch.  My front panel includes an SPDT switch for power, but I didn't connect it.
--
Jon Titus, KZ1G
Herriman, UT USA




Best Mod in the known universe

Richard VA3NDO
 

Here is a 3D printable  .stl file that adapts the audio poteniometer  small shaft to a regular 1/4" shaft.
enjoy.   https://www.dropbox.com/s/gsekbxglstipxee/Audio%20Pot%20Adapter2.stl?dl=0

Richard VA3NDO


Re: uBITX Low Power Output

_Dave_ AD0B
 

For the price of some electret mic I would try a different one. There are differences. Not always based on price. I generally have to get the mic close to get much out of them. Think of how close you are to a phone mic. From a foot back you won't get much out of them.

Have found that I get approx the same peak on mic as the cw carrier puts out.

If you choose to run higher voltage on the finals would put on bigger heat sinks and fan.

I would agree that the metering gets wonky when transmitting into a mismatched antenna feed line. I made this mistake in believing the power meter with a higher swr. Can still pick up a few ft8 signals when on my dummy load so it isn't as dummy as predicted. My shack has metal siding and roof.


Re: Volume Limiting and Distortion Reduction for uBITX #ubitx

Jerry Gaffke
 

There's a lot more going on here than just replacing R13 with a 1n4007.
We need to send a current through the 1n4007 from a control circuit,
the more current through the 1n4007 the lower its resistance and 
the greater the gain in that IF stage.

If you bridge R13 with a 1n4007, then gain in that IF stage
can never be less than that of a stock radio (not good).
Removing R13 from the board will be the least of your worries.

To get any AGC design to work well, you either have to be
extremely lucky or really know what you are doing. 
Or copy a design that somebody else got working.

If you want AGC, I'd recommend dead-bugging the ND6T scheme here:
   http://ubitx.net/category/hardware/agc-mod/
Use the circuit under the heading "New AGC System", April 16 2018.
That is what Kees shipped out as a kit (he has no more available).
Works on both the Bitx40 and the uBitx.

Kees' version uses jumpers to adjust R6 (in the ND6T schematic)
for values between 330k and 2meg, not just frozen at 1meg.
This allows the AGC hold time to be set to your preference.
Making R6 be 0 ohms would shut down the AGC, so it works like a stock rig.
Kees also added some 0.01uF and 1.0uF bypass caps to the 5v rail.

Allison's 1n4007 would more or less replaces Kees' two 2n7002 FET's.
Details of how to implement Allison's scheme are left as an exercise for the reader.
Good luck! If you want easy, I suggest you use ND6T's scheme.

Jerry, KE7ER


On Wed, Dec 26, 2018 at 08:07 PM, Bob Lunsford wrote:
My question is whether merely bridging R13 with the 1N400X would
bring about positive results or if adding the diode would be useful
only if R13 is removed?


Re: Volume Limiting and Distortion Reduction for uBITX #ubitx

Bob Lunsford
 

RE:
Allison recommends using a 1n4007 as a pin diode to set the gain in one (or both)
of the bidi IF amps, many of us have a 1n4007 in the junk box:
https://groups.io/g/BITX20/message/45984

Jerry, KE7ER
~~~~~~~~~~~~~~~~~
The link refers to replacing R13 with a 1N400X diode to assist
in leveling the audio and avoiding the booming effect. The "fix"
is simplicity itself even if not totally effective.

This relates to lack of AGC for the UBITX.

A few times listening to a net where some powerhouse station blasts
the audio line is enough to make this a consideration. Seeing the link
above shows that a simple "fix" may be effective but ass to just how
effective it may be is another factor.

My question is whether merely bridging R13 with the 1N400X would
bring about positive results or if adding the diode would be useful
only if R13 is removed? I know the mechanics of removing an SMD
device but bridging the resistor with rhe diode would be much simpler.

Also, it seems obvious that the diode's cathode would be connected
to ground. Is it so obvious that polarity was not mentioned?

Bob — KK5R

--------------------------------------------

On Wed, 12/26/18, Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:

Subject: Re: [BITX20] Volume Limiting and Distortion Reduction for uBITX #ubitx
To: BITX20@groups.io
Date: Wednesday, December 26, 2018, 11:26 AM

There have been dozens of
threads in this forum about adding AGC to the Bitx40 and
uBitx.
Most get hacked in (both detection
and attenuation) after the rx audio preamp,
to prevent ear damage on a sudden strong
signal.
Then perhaps add a manual RF gain
pot at the antenna port to avoid audio preamp overload.

Some used PIN diodes to
attenuate the signal at RF (or IF) frequencies,
and thus get around the dynamic range
limitations of that 2n3904 audio pre-amp stage.
Here's the earliest thread to identify the
dynamic range issue of that Bitx/uBitx audio pre-amp
stage:
:    https://groups.io/g/BITX20/topic/5945215#32066

Kees (K5BCQ) sold nearly 1000
kits of an AGC design from Don (ND6T).
This
was audio detection with RF attenuation at the antenna port
using 2n7002 FETs.
Nik (VK4PLN) was planning
to sell a kit with audio detection and attenuation
after the audio preamp, I don't know what
came of that.
    http://ubitx.net/category/hardware/agc-mod/
 

Sensing
signal levels is probably best done after conversion to
audio.
Must sense after the 12mhz crystal
filter, or strong signals elsewhere in the band
will bring on the AGC action.  But if we sense
between that 12mhz crystal filter
and the
demodulator, then we will likely be seeing mostly the
unshielded 12mhz bfo.

Attenuation could be anywhere between the
antenna port and the input to the audio preamp.
Putting attenuation at the antenna port avoids
overloading the mixers and IF amps,
but they
generally have enough dynamic range that it doesn't
really matter where we pot it.
Putting
attenuation after the audio preamp works, but does not fix
the dynamic range
issue of that preamp.

Various ways to implement
attenuation at RF, here's a good one that 
tries to maintain a 50 ohm impedance match, and
is quite cheap:
    https://www.nxp.com/docs/en/data-sheet/BAP64Q.pdf

Allison recommends
using a 1n4007 as a pin diode to set the gain in one (or
both)
of the bidi IF amps, many
of us have a 1n4007 in the junk box:
  https://groups.io/g/BITX20/message/45984

Jerry,
KE7ER


Re: uBITX Low Power Output

Rod Russell-Brown
 

Hi Bret,

I got a result, not perfect but It will do for what I want.  I adjusted up RV1, a 100ohm trim pot which is before the final chain.  It didn't solve the problem of why the difference between CW and SSB.  The trimpot cranked the whole output up somewhere near 10w.  I can now get 3w CW and 10w SSB so that is close enough.  As I mentioned in the thread, some bands were higher on CW and others lower.

One suggestion had been that oscillators were giving different outputs.  Never got that far.

Cheers,

Rod
VK1ACE


On Thu, 27 Dec 2018 at 06:07, Bret Mills <bret.wx7y@...> wrote:
Hi Rod, 
Did you ever get your low power issue resolved?
I have finally gotten around to getting my UBITX V3 board done and on the air and I find the same issue as you have described here on this thread. 
about 3 Watt's is about all I can get out and that is on 20 Meters when driving the Mosfet's to about 125MA Bias. 

--
You can email me back direct bret.wx7y@... if you like.
thanks and 73's
Bret
WX7Y


Re: Help on parts and or repairs !

Mike Lichtman
 

Chuck,
Check to see if you have the heat sinks on the finals touching the case. That will blow them. 73 Mike KF6KXG


Re: Changing out L5 & L7 in UBitX for Spur Fix

iz oos
 

How big are the spurs at 12Mhz? Transmitting on 20m I could barely see that on my Softrock receiver (which grounds on TX) and a lot less than the fundamental, seems, I would say at least - 50db. The spur exists but seems to me quite low. Has anyone measured it against the fundamental with a reliable spectrum analyzer?


Il 25/dic/2018 13:04, "Evan Hand" <elhandjr@...> ha scritto:
I ordered the kit from the ubitx.net link on spectral purity: https://ubitx.net/spectral-purity/

I am assuming that it will include the correct devices.

Thank-you for your checking!

73
Evan
AC9TU


Re: Tracing receive signal for low signal

Dave Space
 

Thanks will check.  I was thinking about that before and I tried a random cap I had around but didn't seem to make a difference maybe have to try a different one.


Re: Help on parts and or repairs !

Timothy Fidler
 

Chuck, 

there are cases where people have wanted a new Raduino and hfsignals has allegedly sold one of those , independently of other hardware (via an email enquiry to the gmail.com  letterbox ).  That was $25 USD plus shipping last I saw.  Subtract that from what you paid for your board and that will give you an idea of the cost you are up for.   (A fair proportion of the original price )
2. Re contacting HF signals - you could get cheeky and sniff around for a recent post/ans by A. Farhan on this wunnerful (sic)  BBS and reply to him about cost and arrangements for getting a new main board. 

3. There is another option (but with greater technical risk)  if you have not put it into a min. size case and if the board works fine on Rx. http://www.qrp-labs.com/linear.html  It needs 25 mW to drive it . You will need to ensure you have somewhere on the existing PCB that has this power available.  He does not state the input impedance of the  .... hust ma mouth... look at the input Z measurements by Fred  down the bottom of the referenced page.  BTW others (AN Other) AKA the mad radio modder has allegedly had the modified kit working on 6m SSB and it appears that the Hans 10 W kit is the one to do just that (with other mods on the HF signals board and firmware  too)


Re: Bitx40 No display

courier4000@...
 

Thanks to all who responded,
I was checking solder points with a meter... voltage ect and it blinked and blew a fuse( 2A)     now i get no hiss out of the speaker.... after replacing the fuse....
have good voltage in all points.... speaker checked out OK.

 


Re: Help on parts and or repairs !

Timothy Fidler
 

Basis of  above  rabbit out of the hat statement Drive power  in this case 25 mW =  10 Wout  x Alog  ( - 26/10)


Re: Help on parts and or repairs !

Dexter N Muir
 

Reviewing this tale of woe, I find no mention of initial bias. It's a common failing that people will 'zero' the pots before power-on, and *before* RTFM! Reading that fine manual will reveal the bias pots to be wired the 'wrong' way, i.e. fully clockwise to zero. Leaving them with factory-setting is recommended until either 'fine-tuning' with meter in *each* FET's supply (difficult, not for the newcomer) or complete 're-do from start'.
Hopefully helpfully - and "Best'v the Festive"!
Dex, ZL2DEX


Re: uBITX Low Power Output

Bret Mills
 

Hi Rod, 
Did you ever get your low power issue resolved?
I have finally gotten around to getting my UBITX V3 board done and on the air and I find the same issue as you have described here on this thread. 
about 3 Watt's is about all I can get out and that is on 20 Meters when driving the Mosfet's to about 125MA Bias. 

--
You can email me back direct bret.wx7y@... if you like.
thanks and 73's
Bret
WX7Y


Re: Tracing receive signal for low signal

jim
 

Check (with an ohm-meter) for resistance to ground on generator ...Likely it has 50 ohm to ground ..If you hook that directly across the base of the transistor, you've just mucked up the bias on that transistor ...If you want to random-probe circuits, you need a DC blocking capicitor on the generator lead

Jim


On Wednesday, December 26, 2018, 9:56:42 AM PST, Dave Space <davesspacebar@...> wrote:


Interesting thanks that is a good map to work through will try to trace.

I noticed something interesting maybe it's expected trying to understand why though.  If I input a low signa from generatorl like 10mv 1khz one side of C50 I get a clear tone (the side away from the Q70 base) the other side towards Q70 base I hear nothing unless I increase the power to like 2v or more on the generator  (That could be due to the issue you found with collector voltage I guess... though I see similar behavior on the other transistors inputting to the base Q71, or  (72,73 - I see these in push pull config not sure if that correlates to needing more power at the base).


Re: Volume Limiting and Distortion Reduction for uBITX #ubitx

ND6P
 

Yes, points connected to volume control are in parallel with existing wiring.  The relay and regulator are new, not the existing uBITX ones.   Here is a photo of the mod that I made for mine.


Re: Tracing receive signal for low signal

Dave Space
 

Interesting thanks that is a good map to work through will try to trace.

I noticed something interesting maybe it's expected trying to understand why though.  If I input a low signa from generatorl like 10mv 1khz one side of C50 I get a clear tone (the side away from the Q70 base) the other side towards Q70 base I hear nothing unless I increase the power to like 2v or more on the generator  (That could be due to the issue you found with collector voltage I guess... though I see similar behavior on the other transistors inputting to the base Q71, or  (72,73 - I see these in push pull config not sure if that correlates to needing more power at the base).