... Depending on whose datasheet you look at, the 2N7002 has about a 20 to 50pF gate capacitance and this is apparently sufficient when combined with just the...
IMHO too high values of capacitors should be avoided in this place especially in conjunction with no or too low series resistors. 1nF is sufficient to short...
I wrote to the group a bit ago about not hearing any signals on my recently built ATS-3A. I found out I had a short in my antenna system. I am using a Carolina...
I have the 3, not the 3A, so I dont have the schematic in front of me. But, if the click/thump can be eliminated in the audio section (where is Q2 anyway?)...
... I just made the mod and I got the same results you did, Mike. The same residual click, very small. At the audio output it's measuring 20 mV P-P, which is...
... I've been probing the audio at C18. I no longer see anything there when MUTE goes high, although I do see a bit there immediately prior to that (that...
... I agree. It seems that the crystal is now oscillating, so the MPU is probably running now. 1.5 volts on pin 20 (a logic level) suggests a short that is...
Pics of my version of this mod now posted in my photo folder on the AT_Sprint group site. Look at the area below L3 for the resistor and to the right of the...
... You'll know it when you see it, HI. For instance, the clock will be immediately obvious- it will be there or it won't. You will see gain through...
Hey Steve; The scope allows you to see signals as they propagate through stages. You can also see loading effects, open traces, shorts, etc., *and* see how the...
First off let me say I'm grateful for any and all help w/my ATS! As mentioned it's probably time to move on to a scope. On that note any hints or tips on what...
... This saga is hard to watch. Do you have access to an oscilloscope? You could narrow these problems down in a matter of a few minutes with the right test...
I just did this mod on the bottom of the board. Not much room there either. :) I hope to get pictures up tomorrow morning. I still have a click (audible and it...
Dave - Sounds like a good fix! Question - how did you do it, physically? Looking at the board, that's one of the tightest spots, Q2 nestled right up close to...
Pin 16 and 17 don't look quite right either. Do you hear any audio increase when connected to a noise generator? Do you hear any signals? (Nearby transmitter...
It appears you found U4 was bad and I bet some of the other tiny 4 and 6 pin chips might be in wrong or not soldered. I suggest you just check each of those...
Got more audio but no sidetone or ID yet? UPDATE: I lost the thump on power up and now I get a definitive 'click' but double the amount of hiss it's alot...
Hi Mike, I'll have to check with Steve, but I am not sure if the thump heard is immediately after the power is applied (my ats and ats-3 do this) or is a few...
That thump tells me that the MPU is working (it's the mute line going high), which means the crystal is good. I would check from the MPU to the sidetone switch...
I posted this on QRP-L and thought I'd post it here also, in case some of the members here dont subscribe there.. Installing the 3/3A board in an Altoids can...
... I agree that it seems that the processor's crystal circuit is not oscillating. Check for a shorts or opens on all of the processor's pins, particularly...
I desoldered Q2 and reinstalled it with a 10K resistor in series with the gate and a 0.01uF capacitor from the gate to ground. The thump is absolutely gone...
I've been working with Steve on this, so I've had a little time to look at the data and symptoms. I suspect he needs a new crystal for the CPU - the CPU needs...
Powered up my ATS tonight and got what seems to be audio? I can hear a slight thump when I connect the power plug then a low hiss like the audio chain is...
Cam suggested to me that a 0.1uF from mute to ground helps (C57 would have been a great place to put it -- thanks Cam). It does help -- a lot. BUT as Dave...
... Something outside the BFO mixer area may contribute. If I simply yank out the 40M module (while the rig is powered), the thump pretty much goes away. ...
Very strange. There is definately a little burst of noise being generated after the mute switch goes high. It seems to be generated by the BFO mixer. I removed...
... I think I see it on the outputs (pins 4 and 5) of U2 as well, but,of course, at a lower level. There is very little click on 80, 30 and 20M, but it's...
Two points: o The infamous click is present on several "QRP" rigs in a similar manner. I believe Steve even comments about that somewhere on his site. My...
