#v6 PTT plug on back of uBITX V6 #v6


Hi Ralph,

It seems like the best place would be at the socket for the mic where the PTT connection is made for the plug.  There's also a PTT line at pin2 of the raduino connector.

I think the v6 still has quite a bit of power out variation between the bands.  How do you plan to adjust for that, or are you just sticking to one band?

Have you got low pass filters for the amp (just asking as some don't realize that they are required)?




On Sat, Mar 21, 2020 at 09:55 AM, Ralph King wrote:
I just purchased a XDT-PA70 3.5-30MHZ Class AB Linear Amp to use with my new uBITX V6.

I need to tap into the PTT ckt of the uBITX V6.  I want to put a plug on the back of the case to

accomplish this.  What would be the best spot on the board to solder to ?

Tks & 73

Ralph  K1KOB

Gary Anderson

Using the uBitx PTT signal won't support CW or digital modes.
A direct wire from the uBitx PTT to the Amp's (PTT-)  is problematic as as the bias voltage on that signal is not generically known. Most likely biased at 12/13.8V.

Makes more sense, to me, to use the T/R signal.
One option is to build an identical simple 4.7k Ohm, 2N3904 circuit that the uBitx circuit uses to drive K1 but with the NPN collector now being the signal for the amp's  PTT- (driven LO on TX).

Other's may have better suggestions.


Ralph King

Hi Mark....I'm going to try and use all bands.  There is a low pass filter , multi band unit on e-bay for around $40. with led lights. I might try that with a rotary 
switch.  I need to figure out the PTT first, then on to the rest.  Waiting for the proper USB mini cable to update the software.  I'm having a little trouble getting
the unit calibrated. WWV is around 9.900 not 10MHZ..  Will work on that today. 

Ralph  K1KOB


Ive recently completed this same setup. My amp is the XDT-PA100 with the same LPF you are looking at.
the PTT is triggered by a 5vdc signal. I used the T/R signal as suggested by Gary Anderson. This signal is found at the junction of C150 and R150. See photo attached.
Some caution about this amp. Do not over drive the input, 5watt max input, bad news; more than 5watt and you will be replacing the IRF530 mosfets. good news; they only cost about 1$