Date   
Re: Overvoltage to Ubitx - now no receive

MVS Sarma
 

I do work T 19v using a laptop adopter selected for low ripple. But , I DO TAKE CARE  that a 12v 2 amp regulator supplies to blance circuitry other than the final IRFs. There also the current is adjusted to say 80mA.
If the due care is not taken , obviously components would fail. Om Bose might take a cue from Allison's advise.

Satma vu3zmv



On Sun, 15 Sep 2019, 6:54 pm ajparent1/KB1GMX, <kb1gmx@...> wrote:
Sumit,

You grossly over voltaged the LM386 audio amp.
Other parts are likely suspect but start  there.

Start at the speaker and work back.

FYI: the only parts that would tolerate more than 15-16V would be the finals IRF510.

Allison

Re: Compliance Summary - other radios

Ted
 

Not a bad deal (as of date of this message) considering those "kits" on eBay that self-destruct upon contact with electricity:

  https://www.newegg.com/p/0TF-0002-00002

Re: Flipping Nextion display in software? #firmware #nextion #ubitx

Ted
 

Please don't think of me as obtuse, though, in what way is your rectangular opening "upside down" for the display? 

I would second the recommendation of using a surrounding bezel to take care of this, short of going with a larger size which might negatively alter the paradigm of the rig you're working toward.

Re: Fix for Spurs and Harmonics on V3 Board

Dale Hardin
 

Curt, 

Harmonics.--I have already ordered the new Axiom relays, so I will try replacing the relays first.  I have a good desoldering gun, solder wick, and chipquick, so I should be ok there.  If that doesn't do the job, I can alway add the outboard relays.  Allison mentioned moving the relays to the bottom of the board, so I may add that to the fix. 

Spurs.--Also, both she and Kees mentioned moving the toroids to the bottom of the board.  I may do that first before replacing them.   I do want to do Farhan's V5 fix; it seems simple enough.

 However, I don't know if there is a local spectrum analyzer available to check the results.  I'll have to pursue that with the local ham club. I am looking at using a rtl-sdr and Spektrum as a test instrument if I can't find a local spectrum analyzer.  I already have the rtl-sdr.

As to parts, I need the replacement toroids and parts to do Farhan's V5 fix.  I assume most hams are like me and order parts like that 10 at a time (just in case).  If you have parts to spare, please contact me privately to discuss.

Iz-oos,

I don't think I will attempt the trap fix until I hear from others who have done it.

Thanks for the input, Dale



On Mon, Sep 16, 2019 at 1:30 AM iz oos <and2oosiz2@...> wrote:

About the 12mhz spur, the trap I believe is not that simple. Please let me know a good design without affecting the 30 and 20m bands. Checking it on my SDR receiver is really very low.


Il 16/set/2019 03:54, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
Dale

I can speak to v3 and v4 because they are similar in this regard.

First on harmonics an effective solution involves more isolation in the relays selecting the low pass filters. I am using the external board now kitted by N8DAH. It should make your ubitx compliant on 80 to 17 meters, both cw and ssb. CW tends to be okay on these upper bands without a fix, but not ssb or data modes using the ssb math. An alternative scheme is removing the relays and replacing them with Axicom parts. This tends to be more complex work.

The remedy of the ssb spurs on the upper bands is more challenging. Possibly the Axicom relays may help here along with shielded inductors to replace the toroids at the 45 MHz crystal filter. Others add a second 45 Mhz crystal filter, but without others mods this approach doesn't work for me.

I suggest choosing one of these approaches for harmonics, and working the other matter later.

Curt



--
Dale Hardin
24750 State St. Unit 487
Elberta, AL 36530
251-597-9256

--
Dale Hardin, KS4NS
Elberta, AL

Re: Flipping Nextion display in software? #firmware #nextion #ubitx

_Dave_ K0MBT
 

I don't know about reversal, that would be an elegant solution.

Have you considered elongating or opening in the case and covering it with a bezel.

Order the next larger Nextion and sell the one you have. For me it is only the 3.5" unit (or larger I suppose) that fits my fingers. Have tried all sizes below 3.5". They work if I use a pencil to touch  them but are very inaccurate with my fingers.
--
73
Dave
k0mbt
Ham_Made_Keys

Re: Project : Ubitx go box with batteries (topic will be updated upon works done)

Olivier Grand
 

Nice job Adrien !
73's Olivier

Le dim. 15 sept. 2019 à 22:31, Adrien F4IJA <adrien.grelet@...> a écrit :
So, my uBitx is almost finished !

I haven't made some QSO for now, but I tested it like a WSPR beacon and it's OK (6800km of report max).

Here some views of the beast :


--
73's
Adrien F4IJA
https://www.qrz.com/db/F4IJA

Re: Fix for Spurs and Harmonics on V3 Board

iz oos
 

About the 12mhz spur, the trap I believe is not that simple. Please let me know a good design without affecting the 30 and 20m bands. Checking it on my SDR receiver is really very low.


Il 16/set/2019 03:54, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
Dale

I can speak to v3 and v4 because they are similar in this regard.

First on harmonics an effective solution involves more isolation in the relays selecting the low pass filters. I am using the external board now kitted by N8DAH. It should make your ubitx compliant on 80 to 17 meters, both cw and ssb. CW tends to be okay on these upper bands without a fix, but not ssb or data modes using the ssb math. An alternative scheme is removing the relays and replacing them with Axicom parts. This tends to be more complex work.

The remedy of the ssb spurs on the upper bands is more challenging. Possibly the Axicom relays may help here along with shielded inductors to replace the toroids at the 45 MHz crystal filter. Others add a second 45 Mhz crystal filter, but without others mods this approach doesn't work for me.

I suggest choosing one of these approaches for harmonics, and working the other matter later.

Curt

Re: Fix for Spurs and Harmonics on V3 Board

Curt
 

Dale

I can speak to v3 and v4 because they are similar in this regard.

First on harmonics an effective solution involves more isolation in the relays selecting the low pass filters. I am using the external board now kitted by N8DAH. It should make your ubitx compliant on 80 to 17 meters, both cw and ssb. CW tends to be okay on these upper bands without a fix, but not ssb or data modes using the ssb math. An alternative scheme is removing the relays and replacing them with Axicom parts. This tends to be more complex work.

The remedy of the ssb spurs on the upper bands is more challenging. Possibly the Axicom relays may help here along with shielded inductors to replace the toroids at the 45 MHz crystal filter. Others add a second 45 Mhz crystal filter, but without others mods this approach doesn't work for me.

I suggest choosing one of these approaches for harmonics, and working the other matter later.

Curt

Flipping Nextion display in software? #firmware #nextion #ubitx

Ben Miller-Jacobson
 

Hello everyone. I'm vuilding a uBitx. I screwed up and cut the hole for my Nextion display with it upside down. Does anyone know if there is a way to flip it in software? I intend to use the CEC firmware.

Fix for Spurs and Harmonics on V3 Board

Dale Hardin
 

I soon will be the owner of a v3 board.  After having read way too much information on correcting harmonics and spurs, I think the fixes come down to (1) replacing the relays and putting said replacements on the back side of the board and (2) inserting Farhan's low pass LC filter between the 45mhz IF and the D1,D2 mixer, increasing the 45mhz IF gain (to drown out the 12mhz coming in on CLK2), and a 12mhz trap installed after that mixer.  (Whew, that was a loong sentence)  I understand the first mod, but Farhan's mods as developed in v5 are not documented in ubitx.net (I don't think).  I note that several people have requested a kit of parts to make the fix.  Would some kind soul prepare a set of instructions and BOM for Farhan's v5 fix.  Lastly, are the above fixes likely to solve the harmonics and spurs issue? I really appreciate the work that preceeds this request and hope I can get my v3 board "up to snuff".  73 Dale 

Dale Hardin, KS4NS
Elberta, AL

Re: Amplifier Talk- Communications Concepts

 

Sorry for using "CB amp" as a description,

It isn't a real specification anyway.  I just meant a type of amplifier that was gererally of a simple design that doesn't have a lot of features.  As Alison says, e.g. the EB63 uses basic diode biasing which needs high current in order to maintain a stable bias.  This results in low efficiency and higher battery drain.

Such types might also might be considered a single band design, as there is often only one (or none) lowpass filter.  They also generally have no gain compensation, which means uneven power output has you change bands, which would require transmitter power adjustment to keep from overdriving and burning out the final transistors which are not cheap.

The latter point really makes it not a good match for the ubitx since the transciever already has quite uneven power ouput with good power on the low bands and less and less as you go up.  An uncompensated amplifier will also do the same thing so that can be a troublesome thing to handle.

The AN763 would be a better match up as it has gain compensation built into the design already (no need to figure it out on your own, or extra parts to buy).  It also has a more efficient design for both biasing and for the final transformer (less heat and lower current draw).

Alison, I don't quite get what you said about the copper heat spreader and the AN762?  Reading the construction notes for both the EB63 and the AN763, I couldn't find a mention of that, or that the AN763 would have any more rare parts than the EB63?  Both seemed to be complete kits that only required a large aluminum heatsink and a heatsink fan (besides a case and lowpass filters and switches).

73,


Mark.

Re: Project : Ubitx go box with batteries (topic will be updated upon works done)

Adrien F4IJA
 

So, my uBitx is almost finished !

I haven't made some QSO for now, but I tested it like a WSPR beacon and it's OK (6800km of report max).

Here some views of the beast :


--
73's
Adrien F4IJA
https://www.qrz.com/db/F4IJA

Amplifier board available - cheap

Woody
 

I have rebuilt my HF linear (case and all) and used a BLF-188XR.  Had smoked my previous amp board (AN-758) and just set it aside.  Hate to see it go to waste.  Keep in mind that it will need low pass output filters for the bands desired.
So, wonder if anyone would be interested in owning it... 
 
Asking $25 for the board, no shipping charge (Priority Mail) in the US lower 48, via PayPal  -  Needs new PA transistors, at least.

Minimum gain of the MRF429 is 13db.  For about 8 to 9 watts drive, should make at least 180 watts out.

See applications note (this board is one of the multiple boards shown in the note for a KW amp:
https://www.communication-concepts.com/content/AN758/AN758_Application_Note.pdf

The kit info and downloadable info can be found at:
http://www.communication-concepts.com/an758/
&
http://www.communication-concepts.com/an758-1/ 
They sell the kit for $159.35 (including transistors)

Replacement PAs :  http://www.communication-concepts.com/mrf429mp/   ($106 for matched pair)

The MFR429s must be replaced.  Other semiconductors (See * in image) must be checked and replaced if bad.
The bias regulator (Silver can in pix, is SG FTB016) operation should be verified before installing new PAs !   The regulator on board is a SG FTB016.   In the appnote schematic, the device is a MC1723.  See: https://www.utsource.net/itm/p/302661.html?digipart=1     I am not certain, but suspect any pin compatible 723 regulator, in a TO-100 can package would work  -  If it needs to be replaced.

email me if any questions...
 
Woody  -  KZ4AK   (email good on QRZ)


Re: Amplifier Talk- Communications Concepts

Gordon Gibby
 

Thank you very much for that information, I will try either 450 ohms or 900 ohms, Little noninductive dummy load and a step up balun to match, that should work in the 1 to 3 watt range if I my calculations are correct;  you’ve given me excellent guidance.




On Sep 15, 2019, at 09:21, ajparent1/KB1GMX <kb1gmx@...> wrote:

EXTERNAL EMAIL: Exercise caution with links and attachments.


Gordon,

Short form no.  The 6146 does require power to the grid to run though small.
the key thing is you need 25-50V p-p of RF and to do that across the grid resistor
and the 10-20pf of input capacitance.

The other part is that the bitx needs a stable load and the grid of 6146 is not that.

I'd think at several watts a 4:1 or maybe 9:1 would do.  However if yu want stability 
you have to load that transformer with resistance as the 6146 just like IRF510
is very intolerant of sloppy RF design and will oscillate to destruction.

Allison

Re: Overvoltage to Ubitx - now no receive

ajparent1/KB1GMX
 

Sumit,

You grossly over voltaged the LM386 audio amp.
Other parts are likely suspect but start  there.

Start at the speaker and work back.

FYI: the only parts that would tolerate more than 15-16V would be the finals IRF510.

Allison

Re: Amplifier Talk- Communications Concepts

ajparent1/KB1GMX
 

Gordon,

Short form no.  The 6146 does require power to the grid to run though small.
the key thing is you need 25-50V p-p of RF and to do that across the grid resistor
and the 10-20pf of input capacitance.

The other part is that the bitx needs a stable load and the grid of 6146 is not that.

I'd think at several watts a 4:1 or maybe 9:1 would do.  However if yu want stability 
you have to load that transformer with resistance as the 6146 just like IRF510
is very intolerant of sloppy RF design and will oscillate to destruction.

Allison

Overvoltage to Ubitx - now no receive

sumit basu
 

Hello,

My Ubitx ver 4 does not receive anything now. It was working fine till i tried fiddling with an AGC addon and an external audio amp. I was experimenting with the voltage supply and turned up the knob of my variable supply to increase voltage, at around 19~21v suddenly every thing went silent with a light 'pop' sound on the earphones. I went back to the original v4 audio setup minus all the addon's - but no sound at all.

It seems the transmit chain is working properly, as i can transmit to a dummy load and observe waterfall from a nearby SDR receiver, i can see and hear sending  with my cw key as well as my voice on the SDR receiver but with cw there is no sidetone volume at the ubitx speaker at all. Everthing is just quiet. I had the KD8CEC ver 1..2 installed and that part seems to be fine, i can PTT, send cw, voice and all menus are available and seem like woking, i can change all menu options and verify them using the ubitx manager as well as upload other versions. But no sound.

I tried the raduino diagnostic by VK2ETA and the tests are OK. I am trying to figure why the sidetone volume could not be heard , the only faint clicks i hear on the speaker are when my multimeter leads are touching the leads on Q72, Q73.

Could i have fried the Q72, Q73 as well as Q71 or any other transistor. I have some basic skills in electronics and i have checked resistor values in the audio amp section and they seem OK, also continuity from R250 till the base of Q71 is OK. Also, it seems to me Q72, Q73 might have failed as resistance values across all junctions seem very low. I had also tried  bypassing the audio section by connecting a speaker between the R250, R251 junction and ground - but again no sound of the sidetone.

I am trying to get the sidetone sound up first and then check the other receive sections - any help would be useful.

Sumit Basu

Re: Amplifier Talk- Communications Concepts

barry halterman
 

I have a complete EB63A that has not been built with a heat sink 165mm x 120mm x 40, 15 fins.
Anyone interested let me know.
Barry
K3BO

On Sun, Sep 15, 2019, 7:31 AM Gordon Gibby <ggibby@...> wrote:
Allison—

Can I ask your advice on a boat anchor project?  Soon I will start refurbishing more and more  HW 100s & SB 100s.   I read that only fractions of a white are needed to drive a 6146 amplifier (driving the grid).  It’s a very high input impedance.   We just learned how to make 1 to 49 baluns easily for End Fed half wave resonant antennas...(fantastic results!)

. would some 1:100 or so ferrite Baluns work well to feed the output of a micro Bitx  into the final amplifier stage one of these older boat anchor radios??

Gordon KX4Z




On Sep 14, 2019, at 23:48, ajparent1/KB1GMX <kb1gmx@...> wrote:

EXTERNAL EMAIL: Exercise caution with links and attachments.


Farhan,

Still around and busy.

Check out OZ1PIFs work.  I've run one section of that a 4x4 parallel push pull
on 6M to over 200W.  The yabut is you need 28V power at 15A!  At 12V that
doesn't work well.  The up side is to get that power not much drive is needed
and its easy to over drive it 5-6W was enough.  Its remarkably tough as I
haven't fried it.  The IMD is only OK.  However a really good and heavy built
low pass is needed as the first one with #18 air wound coils heated too much,
#14 wire solved that along with 500V metal clamp mica caps.

A pair of IRF510s can do 40-50w easy at 28V with 1-2W of drive. 
Parallel parts are harder as then you have parallel paths for
RF current to balance.  Cheat on the layout it becomes unstable
or poor power out.  Getting them to as high as 70mhz was not all
that hard if you pay attention to input and output impedance
they must be low for stability and reasonable power.

The 8 IRF510s are cheap but the total system is not cheap as you still
need a big heatsink (130mm by 130mm with 40mm fins  and a  fan) , TR
switching that can handle the power, and a package to put it all in. 
Cheap 28 or 48 volt switching  power supplies are not a solution as
often they are way to noisy on receive.

Things to consider 100W at 12V is about the limit using the right parts.
However the relays now have to be good for at least 5A and 100V
at the output and the input they can be fairly light.  With higher power
higher currents and voltage are the expected thing and parts like
#12 wire, 500V silver mica or ATC 800B are the required parts.

High power (more than 20 or so watts) tends to be expensive and
getting a reliable amp is never trivial task.

Allison

Re: Amplifier Talk- Communications Concepts

Gordon Gibby
 

Allison—

Can I ask your advice on a boat anchor project?  Soon I will start refurbishing more and more  HW 100s & SB 100s.   I read that only fractions of a white are needed to drive a 6146 amplifier (driving the grid).  It’s a very high input impedance.   We just learned how to make 1 to 49 baluns easily for End Fed half wave resonant antennas...(fantastic results!)

. would some 1:100 or so ferrite Baluns work well to feed the output of a micro Bitx  into the final amplifier stage one of these older boat anchor radios??

Gordon KX4Z




On Sep 14, 2019, at 23:48, ajparent1/KB1GMX <kb1gmx@...> wrote:

EXTERNAL EMAIL: Exercise caution with links and attachments.


Farhan,

Still around and busy.

Check out OZ1PIFs work.  I've run one section of that a 4x4 parallel push pull
on 6M to over 200W.  The yabut is you need 28V power at 15A!  At 12V that
doesn't work well.  The up side is to get that power not much drive is needed
and its easy to over drive it 5-6W was enough.  Its remarkably tough as I
haven't fried it.  The IMD is only OK.  However a really good and heavy built
low pass is needed as the first one with #18 air wound coils heated too much,
#14 wire solved that along with 500V metal clamp mica caps.

A pair of IRF510s can do 40-50w easy at 28V with 1-2W of drive. 
Parallel parts are harder as then you have parallel paths for
RF current to balance.  Cheat on the layout it becomes unstable
or poor power out.  Getting them to as high as 70mhz was not all
that hard if you pay attention to input and output impedance
they must be low for stability and reasonable power.

The 8 IRF510s are cheap but the total system is not cheap as you still
need a big heatsink (130mm by 130mm with 40mm fins  and a  fan) , TR
switching that can handle the power, and a package to put it all in. 
Cheap 28 or 48 volt switching  power supplies are not a solution as
often they are way to noisy on receive.

Things to consider 100W at 12V is about the limit using the right parts.
However the relays now have to be good for at least 5A and 100V
at the output and the input they can be fairly light.  With higher power
higher currents and voltage are the expected thing and parts like
#12 wire, 500V silver mica or ATC 800B are the required parts.

High power (more than 20 or so watts) tends to be expensive and
getting a reliable amp is never trivial task.

Allison

Re: Compliance Summary - other radios

iz oos
 

The KL203 senses the RF and less than 1w average power is needed. That is why it works as is with a softrock in AM FM and likely in CW. In SSB the average power is far less as in most transceivers unless a mic compressor is used. A simple mod I believe is simply to increase a little bit the picking of RF at the RX input of the KL203. The KL203 uses a 500V 8.2pf at C1. I would add another 8.2pf in parallel at C1. If you use the KL203 with 1w you may use also a non 500V cap, any will work.


Il 12/set/2019 20:14, "Sajid Rahum via Groups.Io" <zs735=yahoo.com@groups.io> ha scritto:
Hi Allison, i did get the prebuilt band pass filter from ebay.  Wondering if you have any suggestions to mod the KL-203 as well as how to mod it to be more sensistive to lower power e.g. from softrock <1w; I am able to trigger AM but not via SSB.