Posts

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Front panel layout ideas

Vic WA4THRI always enjoy seeing how others have built their BitX’s and has pointed out ideas that others might find useful:

1. Almost everyone places their tuning control to the right, but if you place the Raduino to the right you can easily update and play with the software by just plugging your computer into the USB port [EDITOR:  With a penetration on the right hand side wall of the enclosure for insertion of a mini-USB-B connector.]

2. It is hard to beat the value of the Banggood EF01 instrument case. If you turn it upside down and eliminate attaching the hard plastic feet you have a smoother mounting surface for circuit boards and can use the vent holes for a speaker grille.  Add some stick-on soft plastic feet on the “new” bottom.

3. Using the second line of the BitX display to label switches and controls saves having to find a way to place labels on the front panel.

Reference

 

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Raduino Repair Service

Jim Sheldon W0EB is offering a new service to uBITX owners in the US (sorry no service is provided to foreign owners) to repair Raduinos.

Jim has just finished designing and building a Raduino test fixture that allows him to look at all the signals coming out of the board and also hook up all the digital controls to the board. He has the equipment in his shack to replace the Si5351 clock chip if it is bad and he can also replace a bad Nano (but the customer must provide the Nano).

He’s not sure how long he will be able to offer this, but he is aware that there are a few BITx owners out there that have somehow blown up their Raduino.  It is not that easy to get a replacement at the moment.

DO NOT send Jim your Raduino in need of repair without first contacting him and discussing the problem.  He may refuse to work on it if it appears too badly damaged – that’s at Jim’s discretion.

The offered service is ONLY Raduino repair, not complete uBITX repair.

Contact Jim via his QRZ.com  address (his email address is listed as well).

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Convert your uBITx display to an I2C Display

Andy KB1OIQ has posted a file on the [BITX20] IO Group files page: kb1oiq_i2c_mod.pdf that describes the hardware and software modifications that he performed on his uBITX to free up digital pins on his arduino.  You will need to be logged in to the Group page to access the file.

Andy converts the LCD to use the I2C bus, thus freeing 6 Arduino digital pins for other uses.   Only very minor modifications are required to the Raduino sketch (and you will need to install a different library).  He documents every step involved with photos.   Well done!

[EDITOR Comment – removal of the two pull-up resistors on the additional board and direct connection to the I2C A4 and A5 ardunio pins should suffice without use of a level converter board.  However, the cost of adding in the level converter is negligible and will work well!]

Reference

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New Software Release for TFT Colour Touch Screen

VU2SPF – Dr. SP Bhatnagar (India) and VE1BWV Joe Basque (CD)  are pleased to announce the initial public release of the UBITX Colour Touch Display Controller v2.72u.   
This is essentially  the same as the one for BITX, but modified to work with the UBITX.   The new software provides  a Colour Touch Display Controller with a no menu approach  to control your ubitx .
More info  can be found in the following locations:

The website contains information on how to download the code.

Features:
  1.  Low cost for parts – Suggested parts –  1 atmega2560 – approx $8.00US, 1 Addafruit dds Si5351 – $10.00  –  2.8 TFT  touch colour display     $12.00 US
  2. All bands, band selectivity, USB LSB  -Works well with digital modes
  3. All Display buttons are touch control – and no menus
  4. Any button can have a physical button and a TFT touch or any combination.
  5. 100 memory channels
  6. Tunable BFO’s
  7. 3 VFO’S – A  B  and  MEM
  8. USB / LSB
  9. TX  timeout control
  10. Touch TX button and or physical TX control – for ptt mike or digital modes (vox input low)

Next : New Feature – Working on adding  CAT Control

Connections diagram

Joe VE1BWV subsequently uploaded the connection diagram to show how the Arduino Mega 2560 connects to the display, the si5351a and the main board.

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Typical current draw on the uBITx

Greggory N5WLF  observes that he gets in the range of 1.4-1.8 amps current draw on transmit, SWR depending and asks if this correct.

Feedback from the group suggests that:

  • on receive current draw is around 0.16A for an unmodified uBITx; and
  • on transmit it runs around 1.4-1.8 amps depending on the SWR.  On high SWR the finals can draw up to 2.2A approximately.A 2A fuse on the TX line and 0.5A on the main board seems about right in order to protect your uBITx.

Reference

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BCI filter in the RX line

Nick Pullen VK4PLN has inserted his 3 stage BCI filter into the RX line.

Filter Details: https://groups.io/g/BITX20/wiki/uBITX-AM-BCI-Filter

Nick cut the trace either side of the new HPF board, exposed a bit of the trace and jumpered onto that.   You need to cut the second trace from the PA side (3rd trace down from the 45MHz roofing filter with the crystal).

Taken from the top trace to the bottom in the photo below, starting from the relay on the left and the PA circuit on top:

1: TX pwr to the PA circuits via R89
2: RX path (between K1 and K3 relays. (CUT AND INSERT HERE)
3: TX pwr to the LPF bank.
4: RX pwr to the receive circuit (R18,R38…)

Nick picked up GND from the 2 unused caps C216 and C210 as can be seen in Nick’s photo above.

Reference
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IRF510 bias current

Jerry KE7ER says:

“Farhan recommends 100ma for the push-pull IRF510’s on the uBitx. More is better, you get into a more linear region of the FET. But more means more power getting sucked from the battery if portable, that power gets dissipated as heat in the FET’s.  I’m going with 100ma.

“With a 500ma quiescent drain current when using a 24v supply, each FET is dissipating 24*0.5 = 12 Watts.   That’s a lot of heat. Back off to 100ma and it is only 24*0.1 = 2.4 Watts.   Which still seems plenty.

“You want to be very careful when adjusting IRF510 gate bias trim-pots, take it too far and the IRF510’s might be trying to dump 100 Watts or so.”

Note that a Mitsubishi D16HHF1 in push-pull requires a higher bias current setting (perhaps 250 mA or 300aA).

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Damaging your Raduino

A post fromJustin KN4FAW reminds us all that it is VERY VERY EASY to damage your Raduino.

Justin says “So, I assembled my Bitx40 kit, at this point it was just wires laying on my bench. I wired up the function button, tested, everything working great. Accidentally touched the ground from function button (orange wire) to 12v while moving stuff around. Now my LCD only shows squares, and I can not tune the radio.  Am I screwed?”

Answer: Yes.

Watch out for the two orange wires on the two different connectors.    Check and double check your wiring before powering on.

Justin isn’t the only one who has done this.  Several other group members fessed up to doing the same, or similar.   Arduino Nano pins are not tolerant of 12v.  There are many other ways to destroy an Arduino Nano pin.  You can read about 10 ways to destroy an arduino here.   There may be quite a few more ways as well …

Mike Hagen WA6ISP comments:

“I recommend in building these radios that you change all ground wires to Black and all Power (5 or 12V) to Red. Reserve these colors for just 2 purposes. You can use the wires you remove for additions.

“Leave the molex pin on them. I have a lot of spare Brown ones. I can’t stand an Orange wire being B+ (the term for us old Valve guys)! 26AWG stranded works great.  I purchased a bunch of colors at All Electronics. Molex pins can be acquired at Tayda and Mouser.

“You don’t have to be in such a hurry and blow things up. Check your wiring several times. You could even make a connector chart with J numbers and pin numbers with the associated wire color.  Match it up to what is on HF Signals. It may mean you catch a mistake and save a lot of trouble shooting?”

Reference

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Update on Martin AE7EU Top Board

 
Pictures: Front panel:  Headphone, Microphone, Encoder (from uBitx kit), 4 pushbuttons, AF gain, uBitx standard display.
 
Rear Panel:  +8V input, +12V (or ‘PA’) input (switchable), RF output, Teensy micro USB (CAT), PTT, Key, DSP Audio (from Teensy3.2), Linear control.
Martin AE7EU provides a detailed update on getting his “top board” working:
1) Mechanical clearances are okay.  Front panel mic/headphones need to move up by about 0.15″ to be flush to the encoder/display level
2) .1″ headers are misaligned, just needs adjusting in the gerber files, shouldn’t be too bad.  Big ‘PITA’ will be wiring directly to the uBitx on the first run for power, and since I only care about single power supply, this mod will only be roughly tested.
3) Messed up on a few pin headers on the front panel; mostly in that the pins from the AF gain resistor interfere with the main PCB, requiring that they be sanded down.  A 0.062″ move is all that’s needed.
4) BoM was heavily not optimized.  Optimized out a bunch of components to make everything 50-ohm, 1k, 2.2k, 5k, 10k, and 100k resistors, 0.01uF caps (minus one required 1000pF cap), and removed a bunch of 0.01uF caps that can be replaced with capacitor arrays, but some testing with the new values will need to be done.  Board is populated with optimized values.
5) Footprint for HC595 is incorrect, but usable.  Too narrow footprint, component wider.  Failure due to rushing out the door with the design before checking the footprints on a printout (didn’t have the component in hand).
6) Display module is actually the limiting factor for overall height.  A smaller display module, and the whole thing could fit in 1.25 (right now, designed for 1.5″)
7) PA Gain cutout is slightly off; still useable with a phillips head screwdriver though.
8) Incorrectly specified Aluminum electrolytics; changing to TH in next design, all 10uF
9) Found the RTC battery was almost fully discharged… will have to check out current consumption when not plugged in, it’s probably trying to run the CPU full tilt.
10) Need to change $1.5 PV36W 20-turn pots to 3/4 turn TX33 pots ($.10 each or whatever)
11) Optimize mods comes next after powerup and verification.
12) Need to verify winding orientation of the SWR bridge
Reference