¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. QRPLabs
  2. Topics

QCX CAT Questions .... #cat #qcx

 

I'm about to do the CAT and PTT mods to my QCX20 and have a couple of questions concerning the CAT mod.

Is the best place to pick off the DVM, LCD_4 and LCD_5 directly off of IC2 - pins 25, 2 and 3 respectively? Or would the LCD pins 4 and 5 and the junction of R56, R57 and R58 (for the DVM) be more appropriate?

With respect to the USB to Serial Converter I have a USB TTL Serial Cable PL2303TA. It "claims" to have a real PL2303TA chip and works with WIN10. The actual title of the cable is USB TTL RS232 Convert Serial Cable BUT the pin-out is all at 5 VDC level suggesting TTL.

For an external connection my plan is to take the TX, RX and GND from the QCX to a 3.5 mm stereo jack on the case and then, via 3.5 mm plug, to the converter.

If others who have completed the mod have any hardware suggestions please advise!

Thanks.
--
73, Rick
VE7TK
 

¿ªÔÆÌåÓý

Hi Rick
?
I've carried out the mod on all my QCX's and all works well.
?
I tapped onto the rear of IC2 for all the connections.
Fitted a 15 way D connector to the rear panel of the case, this accommodates the GPS connections, the Firmware up grade connections and the CAT connections.
?
The CAT resistors and diode are directly soldered into the buckets of the D connector pins.
As for the TTL Serial connector I made a mistake by ordering a 3.5v level cable, it seemed to work but was quite erratic at times, the 5v cable cured the problems.
The cable is an RS Stock No 6877770 Manufacturers Part No TTL-223R-5V, Guess you could compare what you have with this one.
?
Hope this is of use.
?
CU in the QSO Parties some time.
?
72/3
?
Ian G4GIR
?

----- Original Message -----
From: Rick Williams - VE7TK via Groups.Io <ve7tk@...>
Reply-To: <[email protected]>
Sent: 23/01/2020 00:24:29
Subject: [QRPLabs] QCX CAT Questions .... #cat #qcx
I'm about to do the CAT and PTT mods to my QCX20 and have a couple of questions concerning the CAT mod.

Is the best place to pick off the DVM, LCD_4 and LCD_5 directly off of IC2 - pins 25, 2 and 3 respectively? Or would the LCD pins 4 and 5 and the junction of R56, R57 and R58 (for the DVM) be more appropriate?

With respect to the USB to Serial Converter I have a USB TTL Serial Cable PL2303TA. It "claims" to have a real PL2303TA chip and works with WIN10. The actual title of the cable is USB TTL RS232 Convert Serial Cable BUT the pin-out is all at 5 VDC level suggesting TTL.

For an external connection my plan is to take the TX, RX and GND from the QCX to a 3.5 mm stereo jack on the case and then, via 3.5 mm plug, to the converter.

If others who have completed the mod have any hardware suggestions please advise!

Thanks.
--
73, Rick
VE7TK

 

Hi Rick,

I soldered two 330 resistors to the LCD pins. I also brought out gnd.

I used 3 clipped leads to connect from there to an Arduino with its DIP 324 chip unplugged. Works great.

I run Linux and used minicom to talk to the Arduino and then on to my QCX20.

Lots of fun :).

On Wed, 22 Jan 2020, Rick Williams - VE7TK via Groups.Io wrote:

I'm about to do the CAT and PTT mods to my QCX20 and have a couple of questions concerning the CAT mod.
Is the best place to pick off the DVM, LCD_4 and LCD_5 directly off of IC2 - pins 25, 2 and 3 respectively? Or would the LCD pins 4 and 5 and the junction of R56, R57 and
R58 (for the DVM) be more appropriate?
With respect to the USB to Serial Converter I have a USB TTL Serial Cable PL2303TA. It "claims" to have a real PL2303TA chip and works with WIN10. The actual title of the
cable is USB TTL RS232 Convert Serial Cable BUT the pin-out is all at 5 VDC level suggesting TTL.
For an external connection my plan is to take the TX, RX and GND from the QCX to a 3.5 mm stereo jack on the case and then, via 3.5 mm plug, to the converter.
If others who have completed the mod have any hardware suggestions please advise!
Thanks.
--
73, Rick
VE7TK
 

Has anyone got a photo of the bottom of the PCB with the pins in question at which to make the CAT connections? I am not able to locate any and I'm hesitant to risk blowing up my QXC(s) before knowing exactly where to tap these - and seeing them indicated on a photo or diagram, and not the wiring diagrams that are out there, I mean actual wires soldered on a successful mod.

Thanks, Rob, KC4NYK
Ham Radio
 

Here you go

--
73, Bernie, VE3FWF
Ham Radio
 

Pic showing CAT wiring to an Arduino acting as a USB to TTL converter
--
73, Bernie, VE3FWF
 

That's it Bernie! Thanks so much! BTW - I like your laser cut enclosure! Question - is it foil wrapped inside for RF/EMF? insulation? I've thought of using other materials for enclosures but wondered if they need to be so insulated.

Thanks again, I'm on it! Manual logging is for the birds!
Ham Radio
 

I have used RF shield paint for some projects, but on the QCX, ?I had no issues - 3 mm particle board worked just fine. ??
--
73, Bernie, VE3FWF
 

Rob, I placed two pictures on the Discord QRP page where you asked the same.

Carel PA0CMU
 

Ok thanks Carel! I'll take a look. Also I have a question about the tolerances, if that's the correct term, for the components in the CAT mod. Namely the 330 and 1K ohm resistors and the 1N4148 diode.

I'm thinking to mount these all on a small board underneath the main PCB held on by adding nylon standoffs to two of the mounting posts for the LCD that would also have a jack there to plug in the TRS end of the USB/TTL cable. I would like to use SMD components for that to keep everything small but there are a myriad of tolerance "flavors" and "thin film / hick film" versions etc. so I'm not sure what people use for the mod - maybe it's not too critical but my gut tells me that with USB and data signals it would be best to make sure they are correct.

Thanks,

Rob
 

I used 1/16 Watt resistors and a BAW62 diode because that's in my junkbox. It works FB Rob.

1 - 11 of 11