Wednesday, 21 September 2022

Hermes-Lite 2

Made some mods to my Hermes-Lite 2 (HL2).
Click the images to supersize.

Added a power on/off switch to the front panel.


Added DC power socket to rear panel, 9 pin sub D for band data to Hardrock 50 (HR50) linear amp and RF3 input for Pure Signal.

Internals (the lumps in the middle of the power cables are gold plated bullet connectors for easy connect/disconnect)

Isolation milled the HR50 interface (provides band data and PTT)
Pin 2 = TXD Band data (Serial out)
Pin 4 = PTT_IN (in from footswitch)
Pin 5 = GND

and simply added pins for a future second amp interface using i2c
Pin 6 = EXTTR_OUT (out to PA)
Pin 7 = SDA2
Pin 8 = SCL2









Second HL2 in a 40mm case !







Saturday, 17 September 2022

Don't shout - WSPR

Homebrew WSPR TX using the brilliant open source code by Harry from Zachtek.
If you want the best, buy from Harry,  https://www.zachtek.com/

I tweaked Harry's code to suit my particular setup(s), initially with a scratchbuilt, single band Tx with GPS - about 200mW out on 40 metres on a 9v DC supply.



I then made a multiband unit using modules from QRP-Labs, including the Arduino shield, si5351 OCXO, relay switch kit and assorted LPF's that all plug into an Arduino UNO.
The OCXO si5351 makes it so much more stable and once warmed up, it doesn't drift - I must try it on 144MHz sometime...



Running at 9v DC in gives an easy 200mW+ on multiple bands, in my case, 4 bands (10, 15, 20 & 40).
It is easily programmed by Harry's excellent Windows software and once the initial settings are done, it needs no further configuration as all important info is taken from the GPS (time, locator etc).
It only needs reconfiguring if you change bands/LPF.




Tuesday, 13 September 2022

Armbian Linux on a TV box

Armbian on an Android TV box

Follow the 1st post here...

https://forum.armbian.com/topic/26978-csc-armbian-for-rk3318rk3328-tv-box-boards/

It's actually quite easy to wipe out the Android install and put Linux on it, just make sure to use one of the RK3318 flavours to 'burn' onto it.
I run in command line only, but it will run the desktop GUI as well, but it's pretty sluggish.

If you 'brick' it, short the 2 pins in last pic and power on and run multitool again

My post is on page 38 of above link
















Sunday, 4 September 2022

Chinese RF Power Meter

My Chinese RF Power Meter has self destructed itself !

It's pretty much as this...
https://www.aliexpress.com/item/1005003572858028.html

Simply powering it on one day and the Q2 transistor glowed and let out the magic smoke.

If you have any idea what the original component marking is, I would really like to know as I can't find any detail about this bit of kit. - see EDIT at end of this post.

Click the images to go 'supersized'


The position of Q2 is just below the LCD on the right side and I have circled it's position in red on the next image after removing the LCD - it's a 3 legged device, probably SOT23...


Close up images



Beneath the top left tin screen is an AD8318 detector + circuitry.

Anyone got the same meter and could read the ID on their existing Q2 chip or better still has a schematic?
Please leave a comment below or my email is good on QRZ.com

EDIT:
Testing the AMS1117 5.0 (5v regulator) it had failed and in failing it went input to output dead short, injecting 12v to Q2 - probably why it smoked!
Q2 is/was a 3v3 regulator and tracing the circuit, it's Vout pin is also connected to the 3v3 pin at top right of the board (big clue there!).  Q2's Vin pad is destroyed, but should be simple enough to 'hot wire' to C16.
So, parts are on order, it must be worth trying to save it for the price of a coffee?