Date   

Firmware loading ignorance

Bill Robbins
 

I now have my ubitx20 v5 assembled.  I was working fine and I had begun the alignment process.  Then it occurred to me to load the KD8CEC firmware rather than going thru alignment twice.

I have loaded sketches previously but it has been sometime.  I followed the KD8CEC instructions (I thought).  But I get no satisfaction.

So I tried to revert to the stock firmware with no success also. I clearly am missing something.

One source of confusion is after I unzip the packages I am left with many files.  When opening Xloader I select one of the files believing that the others will follow.  Nope.

HELP!!

Bill


Re: uBitx v5 issue

Bill Cromwell
 

Hi Ted,

I am preparing to replace Q90 in my V3 and I will be installing the diodes. I have used them in other solid state rigs in the past and a couple of time I have had to replace them (two different radios). The usual failure mode is for them to fail-short. It becomes obvious then that they have failed because incoming signals pretty much vanish. In both cases the rest of the radio was preserved. The sacrificial diodes did their job.

I have never had any problems with radios that have those diodes installed. Most of the caveats that have been posted here are *speculation* about what might happen. It hasn't happened. None of the posts have asserted that any problem has actually happened. I have two experiences where the front ends were saved and no experiences where the diodes caused any problems. And that is experience, not speculation.

73,

Bill KU8H

bark less - wag more

On 11/24/20 11:40 AM, Ted via groups.io wrote:
Would the common 1n914 serve the same purpose?   Being as common as it is, etc.
Ted
k3rta


Re: uBitx v5 issue

Evan Hand
 

Ted,
Yes, the 1n914 or equal would work as far as the information that I have found and what I have tried.  I believe that the 1n4148 is a direct replacement for the now obsolete 1n914.

73
Evan
AC9TU


Re: uBitx v5 issue

Ted
 

Would the common 1n914 serve the same purpose?   Being as common as it is, etc.


Ted
k3rta


Re: New PCB available for WA2EBY linear amp #linear-amp

 

Hi,

It does look nice for single band use as it looks like Sunil has added a spot for a single LPF on the amp board.  Probably it's set up for 10m now, but you could choose a lower band as desired.

73,  Mark


Re: uBitx v5 issue

Evan Hand
 

Jerry,
Thank you for the feedback.  It is a good summary of the data that has been presented in this forum as far as I know.  

No one has yet published any data on either the susceptibility to high RF (what is the actual threshold before failure), on the effect of the diode on Q90 to transmission, or back to back diodes on reception. 

There was concern about the reverse diode on the base of Q90 having a negative impact on the SSB transmission.  Has anyone tried that?  If so, it would be good to know if it works with no adverse effects.  

I have done the back to back diodes on the input to my v4 board and have not noticed any negative effects on the receive capability.  I have NOT done any significant testing to verify the before and after results of the diodes, so this is not conclusive of this being a good solution other than one that works at my QTH where the noise floor is very high.  The high noise could mask any of the potential problems that Farhan points out.  NOTE: the noise issue is on all of my rigs that include an Icom 7300, Hermes HL2, QCX+, and an RSP1a as well as 2 v4 and one v5 uBITX.  I have only modified one of my v4 boards to test the effect of the diodes.

I have not had the Q90 failure problem, mainly because I very rigorously only connect one HF rig to an antenna at a time (I do have three HF antennas up).  I do have a 50 watt Kenwood TM-D710G 2m/70cm that I do use at the same time, and so far it has not destroyed any of my uBITX Q90s.  I have also tried to measure the signal strength of the VHF/UHF antenna to the closest HF antenna, and could not get an effective measurement.  I tried that with my oscilloscope.  The sensitivity is only 2mv/division (1x probe setting).  That should have been low enough to measure any signal large enough to overcome the 0.6volt diode threshold.  The measurements would be specific to my QTH and antenna placement.

To sum up my opinion at this point; without more data, I would do one of the diode protection schemes only if you will be using the rig near other high RF transmitters when connected to an antenna, or if you do experience a Q90 failure.  I am still leaning towards the back to back diodes as that is switched out when the uBITX goes into transmit.  This could be modified to a single diode connected as to protect the base to emitter junction, just installed at the switched point like the back to back diodes.

As a side note, the back to back diodes was cited on this reflector (sorry, I do not have the original post), and lead me to further internet research on my part.  I found that the scheme (with variations) have been used to protect receivers quite often for the exact same reason: protecting sensitive components connected to the antenna from strong RF fields.  Here is one of the articles that I found:
http://www.ad5x.com/images/Articles/FrontEndProt.pdf
and another
http://www.na0tc.org/lib/exe/fetch.php?media=technical:rx_protect.pdf
Both use variations on the back to back diodes.  These are only two of the references that I found.


Jerry, again thank you!  Also thanks to Iz and Farhan for sharing their thoughts.  This is how I learn.
73
Evan
AC9TU


Re: uBitx v5 issue

Bob Lunsford
 

Correction: ...a 3/4-in square heat radiator attached to the regulator....

On Monday, November 23, 2020, 10:38:02 PM EST, Bob Lunsford via groups.io <nocrud222@...> wrote:


Don't recall if my V6 had one but I remember seeing a picture of the regulator and it had a about a 3/4-in square heat regulator attached to the regulator. If one is in your parts drawer, I think it would be wise to attach it to the regulator. Or, you could bend up a small strip of aluminum and make one. No real danger of shorting and no need to insulate it from the tab. It would provide peace of mind when the regulator heats up and most of the heat is drawn away and dissipated.

Bob — KK5R

On Monday, November 23, 2020, 5:03:34 PM EST, Curt via groups.io <wb8yyy@...> wrote:


Bill

great you are checking these things as you assemble.  do examine the schematic and you will see what Jerry is citing - funny thing I was once worried as you!  oh yes - when you power up and touch the regulator on the raduino - don't be alarmed when you discover it is quite warm.  and that your BFO calibration may be way off. 

welcome to the global bitx community.  73

curt


Re: uBitx v5 issue

Bob Lunsford
 

Don't recall if my V6 had one but I remember seeing a picture of the regulator and it had a about a 3/4-in square heat regulator attached to the regulator. If one is in your parts drawer, I think it would be wise to attach it to the regulator. Or, you could bend up a small strip of aluminum and make one. No real danger of shorting and no need to insulate it from the tab. It would provide peace of mind when the regulator heats up and most of the heat is drawn away and dissipated.

Bob — KK5R

On Monday, November 23, 2020, 5:03:34 PM EST, Curt via groups.io <wb8yyy@...> wrote:


Bill

great you are checking these things as you assemble.  do examine the schematic and you will see what Jerry is citing - funny thing I was once worried as you!  oh yes - when you power up and touch the regulator on the raduino - don't be alarmed when you discover it is quite warm.  and that your BFO calibration may be way off. 

welcome to the global bitx community.  73

curt


Re: uBitx v5 issue

Jerry Gaffke
 

I think Iz is right, that DC path does help with static on the antenna, 
which can get quite substantial with nothing more than the wind whistling past.
Evan is also right, the DC path does not protect Q90 from something like
a nearby FM or TV broadcast station due to the 30mhz LPF not allowing it through.

HF will get through the 30mhz LPF, and likely get at least somewhat snubbed out by the diodes in the first mixer.

Gordon GIbby has pointed out that the base-emitter diode of Q90 will conduct
only on positive RF peaks from a nearby (VHF?) transmission, causing C80 to charge up.
The resulting negative voltage on the base during negative peaks can exceed the Vebo spec
of a 2n3904, 6 volts max, and blow out Q90.  He suggests a 1n4148 or similar, anode at Q90-emitter,
cathode at Q90-base, to prevent Q90-base from going more than a diode drop below the emitter, and thus
avoid a violation of Vebo.

Farhan has suggested that there might be more birdies in the receiver if the back-to-back diodes are
added, due to the wideband nature of everything between antenna and first mixer.  The diodes will
create lots of harmonics, creating lots of new mixer products that could sneak through the IF filters.

Most uBitx owners haven't bothered worrying about protecting Q90,
but a few have been bit.

Jerry, KE7ER


On Mon, Nov 23, 2020 at 04:39 PM, Evan Hand wrote:
iz,
The dc path does not really help in protecting the rig in my opinion.  Q90 is the first driver stage in the transmitter, it is connected before the receiver low pass filter, and has been known to fail when the antenna is connected and there are strong nearby RF signals.  There is a preventative measure that I and some others have taken to protect that device.  Back to Back 1n4148 diodes across pins 12 and 16 of K1 would be some protection from strong RF.  Lightning would be beyond the simple diode protection.  A lightning arrestor on the feed line is a better solution to protect against damage from large static discharges, or better yet ground all antennas when storms are near

My opinions so there could be better solutions.  Feedback always welcome.
73
Evan
AC9TU. 


Re: uBitx v5 issue

Evan Hand
 

iz,
The dc path does not really help in protecting the rig in my opinion.  Q90 is the first driver stage in the transmitter, it is connected before the receiver low pass filter, and has been known to fail when the antenna is connected and there are strong nearby RF signals.  There is a preventative measure that I and some others have taken to protect that device.  Back to Back 1n4148 diodes across pins 12 and 16 of K1 would be some protection from strong RF.  Lightning would be beyond the simple diode protection.  A lightning arrestor on the feed line is a better solution to protect against damage from large static discharges, or better yet ground all antennas when storms are near

My opinions so there could be better solutions.  Feedback always welcome.
73
Evan
AC9TU. 


Re: V6 BFO alignment problems after installing AGC

KE2GKB
 

If you continue to have issues Jack feel free to reach out to me or David (N8DAH), Here or at info @ kit-projects and we can help fix and make things right if need be! Almost a thousand happy customers. Let us know how your BFO calibration goes!

-- Tim Keller - KE2GKB https://shop.kit-projects.com


Re: V6 BFO alignment problems after installing AGC

Jack Hunt
 

Update - I tracked down the problem. I had soldered the ground of the BCI filter to what I thought was ground, it was not...

Now I have noise consistently within the band on the BFO alignment tool. Now I just need to do the frequency calibration. I'll do that tomorrow when propagation is better for WVV.

73s


Re: uBitx v5 issue

iz oos
 

I am not totally sure, but that DC Path at the antenna input might provider some degree of protection in case of statics.


Il lun 23 nov 2020 11:07 PM Bill Robbins <wa8cdu@...> ha scritto:
Thanks Curt. 


On Nov 23, 2020, at 5:03 PM, Curt via groups.io <wb8yyy=yahoo.com@groups.io> wrote:

Bill

great you are checking these things as you assemble.  do examine the schematic and you will see what Jerry is citing - funny thing I was once worried as you!  oh yes - when you power up and touch the regulator on the raduino - don't be alarmed when you discover it is quite warm.  and that your BFO calibration may be way off. 

welcome to the global bitx community.  73

curt


Re: uBitx v5 issue

Bill Robbins
 

Thanks Curt. 


On Nov 23, 2020, at 5:03 PM, Curt via groups.io <wb8yyy@...> wrote:

Bill

great you are checking these things as you assemble.  do examine the schematic and you will see what Jerry is citing - funny thing I was once worried as you!  oh yes - when you power up and touch the regulator on the raduino - don't be alarmed when you discover it is quite warm.  and that your BFO calibration may be way off. 

welcome to the global bitx community.  73

curt


Re: uBitx v5 issue

Curt
 

Bill

great you are checking these things as you assemble.  do examine the schematic and you will see what Jerry is citing - funny thing I was once worried as you!  oh yes - when you power up and touch the regulator on the raduino - don't be alarmed when you discover it is quite warm.  and that your BFO calibration may be way off. 

welcome to the global bitx community.  73

curt


Re: uBitx v5 issue

Jerry Gaffke
 

Antenna connector looks shorted to ground because there is a DC path through K3-13,11, K1-12,14, L1,L2,L3,L4, T2-1,6
Jerry, KE7ER


On Mon, Nov 23, 2020 at 12:33 PM, Bill Robbins wrote:
I am just completing my V5.  No power applied yet.   Everything is remove from the board and it lays naked in front of me.  The following connectors are installed; Power, Raduino, Audio, as well as the IFR510's.

My problem is that the both leads of the antenna connector, presumably ground and lead, show continuity to ground.  They are shorted. I find no solder bridges anywhere.

Ideas??

Bill


uBitx v5 issue

Bill Robbins
 

I am just completing my V5.  No power applied yet.   Everything is remove from the board and it lays naked in front of me.  The following connectors are installed; Power, Raduino, Audio, as well as the IFR510's.

My problem is that the both leads of the antenna connector, presumably ground and lead, show continuity to ground.  They are shorted. I find no solder bridges anywhere.

Ideas??

Bill


Re: New PCB available for WA2EBY linear amp #linear-amp

Ken K0KV
 

The bare board should be available on www.amateurradiokits.in  in a few days.  A kit with most of the components will be available later.  

50V is too high - 28V is the absolute max.  It requires at least 4A. 


Re: V6 BFO alignment problems after installing AGC

Jack Hunt
 

Hi Lori's,
Thank you for your input. After posting this I did wonder about a potential ground loop. 

I have noticed that the radio is a lot less sensitive. A +10 station on my Yaesu was lost in the noise on my ubitx, but I put this down to poor BFO alignment.

73s
Jack 2E0GDV


On Mon, Nov 23, 2020 at 07:53 PM, IW4AJR Loris wrote:
Hi Jack 2E0GDV,
 
the problem you filmed in the video would seem to derive from a strange ground loop that somehow affects the receiver, perhaps due to the two ciscuiti added in cascade or perhaps to the arrangement of the AGC switch.
I can't help you more because in my case I don't have this problem, instead, the sensitivity reduction seems to be a typical "disease" of this circuit, in my µBITS.V6 are lost  about 2 S points (10/15 dBµV), I think it is due to the internal resistance of the 2N7000 in series with the antenna, which is always present and which, even if polarized, has a significant loss.
Obviously all is only my opinion, I may be wrong in the measures or have a bit obsolete instrumentation, but my ear does not deceive me, the sensitivity drops a lot!
73 de IW4AJR Loris


Re: V6 BFO alignment problems after installing AGC

IW4AJR Loris <lorisbollina@...>
 

Hi Jack 2E0GDV,
 
the problem you filmed in the video would seem to derive from a strange ground loop that somehow affects the receiver, perhaps due to the two ciscuiti added in cascade or perhaps to the arrangement of the AGC switch.
I can't help you more because in my case I don't have this problem, instead, the sensitivity reduction seems to be a typical "disease" of this circuit, in my µBITS.V6 are lost  about 2 S points (10/15 dBµV), I think it is due to the internal resistance of the 2N7000 in series with the antenna, which is always present and which, even if polarized, has a significant loss.
Obviously all is only my opinion, I may be wrong in the measures or have a bit obsolete instrumentation, but my ear does not deceive me, the sensitivity drops a lot!
73 de IW4AJR Loris

3821 - 3840 of 86823