Quick review of the Kit-Projects AGC board

Jim W0EB, TSW Project Coordinator,  bought two of these kits for his 2 uBITX Version 5 radios. First off, the directions for installing this board are brief, but they are easily followed and the boards are easy to install.

Not wanting to drill a hole for the included switch and run a bunch of wires to it, he just wired the common pad to the “fast” pad for always on, Fast AGC.  A “Via” hole was identified in the trace between R70 and “Vol HI” and Jim ran a wire from there to the “VOL” pad on the AGC board. This worked great.

Even though the “S-meter” output of this AGC system was designed to work with the CEC software, we found it worked with TSW’s BITeensio board as well.

The BITeensio uses the A19 analog input on the Teensy 3.6 for the S-meter. This little AGC system drives the S-meter routines just fine on the BITeensio.

A 50 microvolt (-73 dBm) signal was fed into the antenna connector and Jim adjusted the software’s S-meter routine’s division ratio so the touch screen’s display read S9 as it should with a 50µV input. The rest of the S units were so close to correct that no further tweaking was deemed necessary.

He also found that adjusting the on board RF gain control for max recieved signal was the best way to adjust the level control. As you turn the control counter clockwise, the gain increases and there is a point past which saturation occurs. This is obvious when listening to a weak signal and you can hear the gain drop past this point. Simply adjust the gain to that point and turn it back to where the signal is just peaking.  It is best to just leave it there if you want your S-meter to work right.

Once adjusted, this little AGC board keeps the RF input nicely within bounds on strong signals quite well.

Jim calls out ND6T and N8DAH and says “Well done guys, well done! The kit is certainly worth the price IMO”.

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TSW introduces adapter to protect DC input

Jim W0EB, TSW Project Coordinator,  has announced he has just got the boards and all the kit parts for this little adapter that allows the DC input for your µBITx (or any other kit or homebrew rig) to be protected.

The board allows connections for optional Reverse Polarity (series Schottky diode), a switch on the volume control (or separate power switch) and the switched DC output to whatever item is being powered.  This is achieved t through a small PC board using MOLEX or MOLEX Style male/female connectors. Everything can be plugged in and unplugged for ease of troubleshooting without having to solder or unsolder wires from the rig’s terminals.

TSW is making either the bare board or a full kit of parts available.  The picture shows everything that’s included in the kit.

Full details are on the TSW website

The manual for the SwitchedPowerAdapter is available in PDF form so you can see what it’s all about.

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Antuino under design

Ashhar Farhan VU2ESE and designer of the µBITx has announced that he is working on a new kit – the Antuino.

The PCB version of the Antuino (The Arduino based Antenna Analyzer) is still under development, but we will all be looking forward to its release.

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CW Zero Beat Kit

David  N8DAH has been working on a few projects.    The first of these is a CW Zero Beat

If anybody is interested in a CW Zero Beat addition to their µBITx, then he  has nine in kit form and one built for testing available.   The kits are US$13 shipped inside the US.  Add actual shipping costs outside Continental USA. He can build them for you for $2 extra or only solder the surface mount and allow you to build your own.

J1- Power in 9-12V

RV1- Audio in adjustment

J2- Audio in

RV2- Center Freq Adjustment

Questions please e-mail David direct

David is also working on a new digital controlled audio level project (AGC) and hope to have more info soon but this is still only in the prototype stage.

David’s website is:  Kit-Projects.com

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Kees has been busy sending out boards!

Kees K5BCQs has 403 paid orders for AGC and/or Anti-pop Mini-Kits and 399 of these have been shipped.  He has additional boards and parts and will continue to supply these Mini-Kits as long as there is demand. Details are in the “Files” section of the BITX20 webpage under his call K5BCQ.

Kees was somewhat surprised to be able to process such a quantity over a short period of time. That indicates there are opportunities for others to join in with their ideas. As Kees notes, the uBITX is a great vehicle for modifying and improving.

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Port Expander for the uBITx

Mike, WA6ISP has a small PCB that will add 16 more I/O Lines.  It runs on the I2C lines, along with 5V and earth.    It is 1.750″ x 1.100″  and has 3 address lines, so you can run a several of them and they won’t interfere with the SI5351 (which also uses i2C lines).  The chip uses the Adafruit Library for Microchip I2C Expander.  Mike has a few built up versions and a few bare PCBs.  Email him if interested using his BITX20 list email address.

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BITx AGC kit

David N8DAH has assembled AGC kits for BITx transceivers.  These were designed for the BITx20 and BITx40, but should work fine in the uBITx.

The AGC design was posted on DuWayne KV4QB’s site found here and used with permission. All kits will come with:

  • PCB x 1
  • Parts placement layout x 1
  • 2N3904 x 1
  • 2N7000 x 1
  • 47uf x 2
  • 1N4148 x 1
  • 100R x 3
  • 100k x 3
  • 10k x 1 this is extra for the user to play with attack or input values.
  • 2k2 x 1
  • .1uf x 2 unmarked tan

Missing parts will be replaced.   

This is the 3rd run of the boards.  Many group members have this AGC already in use.

Cost and options:

#1 – Kits 13$ shipped

#2 – Pre-built OT service 15$ shipped and tested

Write to David if you want to reserve a kit.

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NB these are sold out as of 29 January 2018.