Date   
Re: Messed up removal of TDA2822

Sajid Rahum
 

You can see the first one on the top left where the concern is on the first photo.

Messed up removal of TDA2822

Sajid Rahum
 

All:
Need help. I cut the TDA2822 (WX model) and tried my best to get the pins out - used copper wick etc. no luck.  

Landed up wiring the 8 pin dil with replacement NJM chip.  When i turned around, looks like one anchor dropped out - you can see the flux showing. 

My worry where did that bit that dropped out was to go to?  I will place a wire if needed.

This was been a nightmare replacing the 2822.

Any suggestion is welcome

Re: RF power chain mods and improvements..

K9HZ <bill@...>
 

I have made roughly the same mods after simulating them in LTSpice and can confirm almost identical results/ power levels. 

 

Dr. William J. Schmidt - K9HZ


On Jun 11, 2018, at 5:32 AM, Nick VK4PLN <nickpullen@...> wrote:

Good Morning Allison, et al.

Just thought I'd throw a few cents in the hat.

I have managed to get my uBitx to output 16w at 80m to 14w at 10m. (CW key down)
In a nutshell, Q90 changed to MMBTH10 (20 for a few $ on ebay...) 220/300  pf cap across emitter resistors of all 3904 drivers, 2:4 wind BN43-202, 330pf mica on input. and RD16 with std feed back in place. Drive RV1 at 3/4. (maybe 20w at full?)

I have yet to check IMD and such but output seems stable.

I need to do more learning/testing...

My second ubitx will get the same mods except all the driver 3904 will be changed to MPSH10... and a common power feed(L8/L9) to the RD16 via a FT50-43 Bifilar. I have worked out a neat way to implement this on the STD board... Pics to come...

73 Nick VK4PLN 

Re: Auto Tuner?

K9HZ <bill@...>
 

Programming is all that is left. 

 

Dr. William J. Schmidt - K9HZ J


On Jun 11, 2018, at 7:44 AM, W2CTX <w2ctx@...> wrote:

What is the status of the uBITX automatic antenna tuner that was discussed late last year?

 

rOn

Re: RF power chain mods and improvements..

Nick VK4PP
 

Just a hint for those experimenting, Jarred, VK3BL has done a great set of Vids on using an SDR as a station monitor for checking IMD...

https://www.youtube.com/watch?v=ZCdiz9Ggmh4

73 and enjoy.

Auto Tuner?

W2CTX
 

What is the status of the uBITX automatic antenna tuner that was discussed late last year?


rOn

Re: uBitx daughter board

Andrea Contini
 

Hello Howard,

Your board is really interesting. Thank you for sharing it.

Andrea

Re: BITX QSO Afternoon/Evening, Sunday, June 10, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Jay - WS4JM
 

Heard N4AYE from FL into Middle TN, Lots of lightning static from storms, rough copy

WS4JM

Re: RF power chain mods and improvements..

ajparent1/kb1gmx
 

For futures [HFsignals] the SMT parts are a good choice as machine stuffed
lowers cost too.


Look at the EBY and HF Packer amps, also the K5BCQ for examples
of how to lay out just the IRF510 (or RD16) for performance and stability.

Allison

Re: External Amp

ajparent1/kb1gmx
 

For low pass filter either T50-2 bekow 10 mhz and T50-6 above as that is the most
commonly used.    The 61 mix has too high mu and is prone to overloading and
heating as anything but transformers at HF.

Wire, I'd use #26 if it fits or #28 as fallback.

Allison

Re: RF power chain mods and improvements..

Jerry Gaffke
 

Allison,

Yes, surface mount parts into current boards would be tough.
The to-39 and to18 parts are fine for current rev boards, no point in saving 
a couple bucks and then spending hours trying to whack them into place and heatsink them.

But nice to think about what hfsignals might do in the future.
If the smt 2n5109 is cheap or an smt 2n2222a works in the driver stage,
the additional cost in parts might be held to a dollar or so.

Could be that the IRF510's and others will behave better at 30mhz if laid out differently.
And not having so much RF on the main board might even help those mixers out?
If so, a Q30-to-IRF510 daughterboard makes good sense.
And as you say, many here will prefer that to swapping out a half dozen transistors and rewinding torroids. 
Especially since with the daughterboard it could be easily reversible, back to a stock uBitx.
 
Jerry


On Sun, Jun 10, 2018 at 01:24 pm, ajparent1/KB1GMX wrote:
Jerry,

The DXT2222A-13 is a possible choice for pre-driver as the power is fairly low.  For the driver
the board layout to get the tab on enough copper is nasty space wise.  I've used that part
and its otherwise a good SOT89 2N2222A maybe a tiny bit better (lead inductance is smaller).
It would be hard to apply to the current V3 and V4 board. 

The SMT 5109 is not useful for the same reasons [board layout] for the driver. it
would work a bit better for the pre-driver. 

NOTE on SOT89 the pinout is BCE and the boards are EBC so attaching them to existing
boards would be very messy with lots of cutting and jumpers even for test reasons. They
would also need a flag to radiate the heat (copper .020 thick by .25 side and .4 tall.).
Someone else can do that for a test.

The BFR106 works for Q90 and also in the 45mhz IF amp section very well.  Its not a choice
for other parts of the radio. As more power capability is needed or 3904 is fine.

One possible layout I looked at was strip the power amp completely Q90 though IRF510s
and have a board above the main board carry the input filters, improved amp, then 
using the output  filters on the lower main board. Two pieces of coax and a few control
lines. That and other added features as there would be space.  That would make an
upgrade far easier as its a whole board and wires. 

Allison

Re: RF power chain mods and improvements..

Nick VK4PP
 

Good Morning Allison, et al.

Just thought I'd throw a few cents in the hat.

I have managed to get my uBitx to output 16w at 80m to 14w at 10m. (CW key down)
In a nutshell, Q90 changed to MMBTH10 (20 for a few $ on ebay...) 220/300  pf cap across emitter resistors of all 3904 drivers, 2:4 wind BN43-202, 330pf mica on input. and RD16 with std feed back in place. Drive RV1 at 3/4. (maybe 20w at full?)

I have yet to check IMD and such but output seems stable.

I need to do more learning/testing...

My second ubitx will get the same mods except all the driver 3904 will be changed to MPSH10... and a common power feed(L8/L9) to the RD16 via a FT50-43 Bifilar. I have worked out a neat way to implement this on the STD board... Pics to come...

73 Nick VK4PLN 

Re: External Amp

Nick
 

Allison,

Thanks for the reply! I will read the articles regarding WA2EBY.

For the low pass filter I am using T50 the actual Fair-Rite part number is: 5961000301 which is mix 61, lower permeability and should be lower loss at HF. It could be that the whole system like you said is not stable as I have seen the distorted waveform at the input of the amp.

I will likely order some new MOSFETs and give it another go. The gate resistors might be a good addition.

I have attached what I put together in LTspice for anyone that wants to play with it. I did not put in an accurate representation for the transformers but I think the ratio is correct. What I have could be completely wrong.

--
Nick

Re: External Amp

ajparent1/kb1gmx
 

A note: the commercial version of the 'EBY amp is the K5OOR HF packer.
the power supply is unique as it runs only on TX and does a 12 to 24V boost
to power the IRF510s to high power.  

Allison

Re: RF power chain mods and improvements..

ajparent1/kb1gmx
 

Jerry,

The DXT2222A-13 is a possible choice for pre-driver as the power is fairly low.  For the driver
the board layout to get the tab on enough copper is nasty space wise.  I've used that part
and its otherwise a good SOT89 2N2222A maybe a tiny bit better (lead inductance is smaller).
It would be hard to apply to the current V3 and V4 board. 

The SMT 5109 is not useful for the same reasons [board layout] for the driver. it
would work a bit better for the pre-driver. 

NOTE on SOT89 the pinout is BCE and the boards are EBC so attaching them to existing
boards would be very messy with lots of cutting and jumpers even for test reasons. They
would also need a flag to radiate the heat (copper .020 thick by .25 side and .4 tall.).
Someone else can do that for a test.

The BFR106 works for Q90 and also in the 45mhz IF amp section very well.  Its not a choice
for other parts of the radio. As more power capability is needed or 3904 is fine.

One possible layout I looked at was strip the power amp completely Q90 though IRF510s
and have a board above the main board carry the input filters, improved amp, then 
using the output  filters on the lower main board. Two pieces of coax and a few control
lines. That and other added features as there would be space.  That would make an
upgrade far easier as its a whole board and wires. 

Allison

Re: RF power chain mods and improvements..

Jerry Gaffke
 

That looks very promising!
Looking forward to seeing where this comes out.

A few obvious observations:

The BFR106@1000 is $0.10, the 2n5109 @ 1000 in a to-39 from Central Semi is $1.50.
Those seem excellent choices if they work.
Looking like these fixes to the uBitx might get done for around $5-$10 more in parts cost, no board changes.

That 2n5109  is cheaper than two of the 2n2222a's in a to-18.
Though the DXT2222A-13  in a SOT-89-3  can be had for $0.10 @ 1000
Central Semi has a 2n5109ub in surface mount, they claim it dissipates a Watt, can't find a price. 

I'm fine if it comes to a fourth stage on a small daughterboard placed between T8-5 and RV1.
if that makes upgrading old boards easier.  (I know, broken record.)

Weird that my search of post  https://groups.io/g/BITX20/message/51550  didn't find any of these higher Ft NPN's.
Either the Mouser parameterized search tool is not very reliable, or me.

Jerry, KE7ER


On Sun, Jun 10, 2018 at 10:54 am, ajparent1/KB1GMX wrote:
Gain and power line up with a few possible solutions listed:

Re: External Amp

ajparent1/kb1gmx
 

Nick,

That amp with IRF530s was created back in 1999 and known as the "hints and kinks"
amp.  When Wa2EBY tried to copy it he got your result blown transistors.  Its unstable into
reactive loads (mismatches) and the transformers were poor.  It also presents a rather
reactive load to the driver (QRP rig) and is known for making that final oscillate as well.

IF the low pass filter is heating either the design Q is too high or the harmonic content is.
assuming the cores ar T37 size.  IF T50 something is wrong as I've run 60W though those.

FYI I also tried that amp (two IRF530s), it tried to blow!  I used a current regulated power supply
so it could never exceed the blowup current.  The only things that helped was a better output
transformer and a 3DB pad at the input to keep the input tame.  I abandoned it.

The 100/150 ohm resistor are negative feedback in an attempt to stabilize the amp. 

For the 'EBY amp 2W is max power as at that point that amp is cranking serious power.
That and more power will likely fry the gates.

Look at the WA2EBY amp (it is the two files [HF use fet] in files under my call).  With 2W I see
at  80 and 40M about 55W at 28V using 2 IRF510 and about 37W at 10M.  I got a board
for it from FARCircuits.  I use it with a 4db input pad as most of the HB rigs I have do
about 4W.    Do copy the mechanical layout as its critical to cooling and stability.
FYI I bilt mine back around 2006 and its still running despite various "operator errors".

One note.  one must use very good care with parallel MOSFETs regarding layout.
They are known to become unstable and fry.  Adding  a 1-4 ohm SMT (1206) resistor
right at the gate before it goes into the part can calm them.  FYI SHORT leads, the
board and the heatsink should nearly be one unit and the MOSFET leads short as possible.


Allison

Re: RF power chain mods and improvements..

ajparent1/kb1gmx
 

On Sun, Jun 10, 2018 at 09:23 am, ajparent1/KB1GMX wrote:

Gain and power line up with a few possible solutions listed:

*Mixer output at full tilt about -10 dbm.
Go higher and the spur gets bigger so lower output here is better.

==========================================================================
*Q90 no mods at 80m about 16db at 10M about 10-11db  and not more than 3mW power.
Replace it with a really hot transistor.  BFR106 has a FT of 5ghz and can do over 100mW.
This should keep the stage gain at about 16-18db from 80 through 10M and deliver the 3mw!
It is the easiest stage to make flat and high gain as this get more difficult at higher power out.

==========================================================================
*Pre-driver takes that 1mw and boost it to about 40mw, We hope.  What I saw was about 45mW
 at 80m and barely 8mW. note gain at 80m is about 16db and at 10m maybe 9db.

We need the gain again to be more stable and higher as well.  Transistors tried that worked better
included the TO18 2n2222A, 2n3866, and 2n5109.  The 5109 was best even though I used only 1.
Second best was tie between a single 3866 and two 2n2222.  MPSH10 was disappointing.
*** I plan to try an oddball 2n6661A, [at 14$ each most will choke] a VMOS fet has potential
and requires many circuit changes[Bipolar bias to MOSFET].  They worked really well in
another project at VHF.

==========================================================================
*Driver take that 40mw and make about .4W at 80 and sinks to barely .08W at 10M Gain for that stage
is supposed to be about 16db and likely is at 80mbut at 10M measured for different 3904s 8 to 11db.

This is where the 2n3904 really fails. Its bandwidth at high currents actually does down.  The 2n2222A
has the reverse, the gain and bandwidth increased with increasing current.  While not an ideal part
it does work better.  The ideal part dow be two devices push pull [not 4] and higher FT.   I havent
tried 5109 here but its a solid bet.  I wish 2n3553s, 2SC2166, 2SC799, 2sc1306 and others were
still around [real ones].

*** I plan to try an oddball 2n6661A here too as its good for up to 6W.
==========================================================================
*Finals IRF510 at 80M approaches 15-20W with a gain over 17db, at 10M its about 13db and but
the drive is so low that yields maybe 2W.

If there is enough power at the gate it does the job we ask.   RD16HHF does not offer more gain or
bandwidth as MOSFETS do not have the equivilent of FT.  IT does offer a handy groundable tab.
==========================================================================

To go from -10 dbm[.0001W] to +40 dbm[10W] we need 50 db of gain over all.  That includes
losses to transformers and other circuit features.  So we need more gain than that by maybe
6 to 10DB to allow some latitude on the gain adjustment pot.

So with four stages and the last being limited to the IRF510s.  We set a few rules.

*One we never run a transistor wide open as one may exceed and another fall short.
For 2n3904s that happens and the lowest common denominator for them is around
10db. Use better transistors and lots of feedback.  More likely to work for everyone
than a bet on Monte Carlo.  

*Two we only have four stages!  The board is layed out that way.  Reality sucks.

*Three:   IRF510 or RD16HHF you get about 13-16db of gain, period.  More
is wishful thinking or running wide open and risking stability.  Hint IRF510s blown
about 2$, RD16HHFs blown 10$.    Going to IRF520 and 530 not better [for 10W]
as the internal capacitances are significantly higher and it doesn't make the drivers
job easier.

*Four Based on total gain needed and what the finals can be reasonably expected to do...
 The three prior stages must deliver 45 to 47 db of gain.  Its also a lot so attention to
 stability is everything.

*Five  the result must be stable.  Oscillation will kill the finals.

Item four is the killer as its basically asking for 16db from all three stages.
You need good parts for that.  Also the interstage coupling must be up to the job
while not introducing uncontrolled losses.  Tall order.  So far I have only partial
answers.

==========================================================================
Dump the 3904s and use 2n22222(to18),  for those interested in 80-17M it works remarkably
well and give a boost up high too.  If you go to 2n5109s you may need 1 is predriver and 2 in driver
besides they are big and the space small.  Whatever is use SHORTEST leads possible.

Replace or parallel R941,R911, R96,R942 to get 11 ohms each (I paralleled 22ohms across them).
Lower emitter resistance helps gain and power out to finals.

Replace Q90 with BFR106,  note R81 has to be increased to between
2K and 2.7K for this part.    (for those making suggestions I tried 2n2369 in
SMT, it was better but not great).  Besides mouse has the BFR106 for a
whooping 38 cents each.

Change C81 to 470 pf,  This flattens the 80 and 40M runaway power and helps the higher bands.

There are many changes to transformers possible but for the moment the above are best bang for the buck.
Aslo changing the transformers might be a handful for some.

Warning every time I tried the 2;4 turn transformer with any ferrite the finals were heating a lot and the
stage efficiency was well under 40% [terrible with IRF or RD16].  The 2:3 was better at high power
but below 50%.  This is still in the grinder...

==========================================================================

Allison

Re: Raduino_v1.27 will not compile

davidzdeb@...
 

ah, thank you everyone.  I have never used github before.  This rig has made me learn so much.

Re: Raduino_v1.27 will not compile

Allard PE1NWL
 

Here's how to download and compile the sketch:

1. On the github page, press the green button "clone or download"
2. Open the downloaded file "bitX40-master.zip" and extract all files to a location of your choice
3. Go to the extracted folder "bitX40-master" and open it
4. Inside this folder there are several files. Find the file named "raduino_v1.27.7.ino" and double click it
5. The Arduino IDE will start
6. A message box will pop-up: The file "raduino_v1.27.7.ino" needs to be in a sketch folder named "raduino_v1.27.7". Create this folder, move the file, and continue?. Click YES.
7. The downloaded sketch will now be opened and shown in your IDE.
8. In the IDE, go to Sketch => Verify/Compile (or press ctrl-R), then the sketch should be compiled without errors.

73 Allard PE1NWL