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Glad to hear there's a chance the rest of the board survived. The ADC was the only component I found that was getting hot. If it's dead that would explain the demonic sound that was coming out of the

I've completed assembly of my QCX+ MIni kit for 20 meters (Rev 3), and I have a control chip that seems to work just fine for 10-60 seconds after power-up, but then after that time interval, the

High Phil, I traced through the Rev5 board to the MPU pin 52.? The Rev2 board has the through hole for the jumper, just not the ground.? If you look above the b in Qrp Labs, you should find a hole

Greetings All My problem involves a QDX running/controlled by WSJT-X v2.5.4 (and v2.6.1) on a ThinkCentre M910q computer w/UBUNTU OS and hamlib v??. WSJT-X v2.5.4 was running FST4W for weeks 24/7 TX

Chris, Were your RF sweeps OK before you fixed T507? I ruled out T507 because my RF sweeps were fine and it seems that either ADC_FWD or ADC_REV are being used to collect the output measurements for

An update: Here are my readings with an estimate of the efficiency and current @12VDC and output per band. RF output varies slightly from yesterday's values. The current draw on 17M seems high as

That's one method. Actually, all that's needed, is a transmitter, and something to generate tones to produce an image. SSTV isn't limited to a band, or method of modulation. I started out with

Hi All I have completed the terminal access and found strange results on the diagnostic test. As expected the right enc button and right tactile button test gave a faulty result because both indicate

Roger that, Bruce. We agree on all points here JZ

ham radio SSTV requires a SSB transmitter running USB (Upper Side Band) with a voice bandwidth of at least 2.4 kHz /g/MMSSTV/topics 72 73 John N3AAZ

John Agree on the electronic downsides of vast copper pad areas but every little helps a bit and also transfers some heat to the PCB material too. ?Generally keeping junctions below 100C whatever

Kevin, Evan, and Jeff, I have seen at least two other cases of ADC failure after a 5V fault event. The ADC analog front end is the weak link of all the devices that connect to the 5V rail. The power

Nate Vibration, significant current, dust and repetitive thermal movement are all harbingers of doom for sockets. There is a reason their use in production (widespread in the 1860s and early 70’s)

Adrian, you are correct. Further, that low level of capacitance is nil compared to the self capacitance of the 47uH inductor, which is probably in the range of 25pF. I think your BAT85S should work

Dean, That is correct. BS170 are made in Vertical DMOS technology. The drain connection is literally the backside of the die which sits on the flag portion of the lead frame. Thanks for sanding one

I was curious what the BS170's look like on the inside so I sanded a couple of the ones I removed a while back because I let the smoke out of them. I have attached a picture here. The left one is the

Thanks John & Hans, Looking to the capacity to rev. voltage graph from the data sheet, looks like C should be around 4-5pF for a negative bias of 3.3V. 10pF was listed for a 1V reverse. Will try it

Hi Evan. I've also discovered that the ADC is getting very hot, so I suspect it's damaged. I don't have the skills to replace an SMD component. At this point I think I should leave it to someone who

I'm just beginning the build of my 20-10 meter Rev 2 QMX, received a few weeks ago. I'm at the point of winding T501. Before I go any further I was wondering if there are any corrections to the

I tacked this question on to the end of another thread a few days ago but got no answers. So, here goes again: I am converting a low band QDX to high band. I've ordered the conversion kit from