It sounds like the keying circuit is not working as advertised. I think you've already gotten that far since you can hear at least the oscillator and the LED is on. ?I'd first check Q3 is indeed a PNP (2N3906/2N2907/2N4403, etc.) and installed correctly (orientation/solder) and the values of related parts are at least visually correct.
For good measure, check if the jumper above R4 isn't somehow shorted to Vcc (e.g., in the wrong spot)
-HRS
P1 is a "drive" control and will vary output power.
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On Mar 7, 2024, at 12:25?AM, Jim Bennett / K7TXA via groups.io <w6jhb@...> wrote:
?Hi - new to the group, need some troubleshooting guidance.
I just finished assembling the Two Tinned Tunas kit and have issues. Let me begin by saying that I'm no E.E. - I've been a programmer/analyst since 1967, not an electronic guru. OK, On the positive side, no components let out the magic smoke when I powered up the rig. But... the red LED comes on immediately after applying 13vdc power - no key plugged in. In addition, on my Kenwood TS-890 I do hear a weak tone at 7.029.584 as soon as power is applied. With power off, I checked the key contacts for continuity and they are NOT shorted out.
I did some voltage measurements and am puzzled by what I see. At the power input side of R9 (and the base of Q3)I have 13vdc, as expected. On Q3's Emitter and collector is about 3VDC. Why is there voltage there with the key not pressed?
Second question - is the LED only supposed to light up when the rig is keyed?
Third question - what is P1, the variable resistor supposed to do?
Now, taking one step backwards, when I first applied power I noticed the LED light up without being keyed so I shut it off and started checking my work. The one thing I did find is that the instructions for Q2 did not match up with the type of transistor that I got. The instructions had me build those funky little things to plug Q2 into and the outline on the silkscreen did not match the style of the 2N2222 I got. Closer examination showed that I had got the emitter and collector reversed. Not knowing if this may have damaged the Q2, I replaced it with a new one I had tin stock and put it in the right way. Would having the emitter and collector installed reversed on Q2 case any component to be damaged?
Anyway, if anyone can shed some light on what might be wrong or where I can look next, that would be greatly appreciated.
Regards, Jim / K7TXA ? ? ? ? ? ? ? ? ? ?
