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Hi Myron, Further up this thread, Hans has indicated he’s aware of the issue and it is on his list. It has affected me too since the beginning of my QMX revision 1. ?The issue has been raised in

Hello Steve Yes I agree it is optimized for 15m, but not intentionally, as you see both of the QMX+'s show 15m the best. I tried to optimize all three bands in that LPF set, but it wasn't easy. I am

Here's some pics of a cooling mod I did on my HB QMX.? It involved spacing the bottom cover away from the main PCB with small nylon standoff which opens up the sides for airflow. I figured its ugly

Steve, The turns ratio of T501 from primary to secondary is higher if you build the radio for 9v instead of the more typical 12v. That higher ratio means a 9v build running on 9v has about the same

Exceed the limits of the BS170s and they expire more readily.? Higher voltage is more power also when there is SWR issue higher current. For 9 or 12V the transformer ratio is used to limit power at

I have had those leading-edge audio thumps since the beginning of my QMX (v27 FW) as well and wondered if it was going to be fixed but it doesn't even look as though its on the list to get fixed. To

Steve, the power to the finals goes through Q507 to L502 and then to the center tap of the primary of T501. The two ends of the primary winding of T501 then go to the drains of the finals. Look at the

One thing that I haven't figured out yet is how the power gets to the finals. I don't understand how a 12 Volt supply is equivalent inside the radio to a 9 Volt supply.? Yes there is a transformer

Hi, Mike. No tuner but the Oak Hills Research WM-2 QRP Wattmeter indicated equal forward and reflected power ( about three watts ) so I imagine VSWR was very close to Lazy Eight ! 72, Bill, N4QA/4

Ian, My LPF plots are very similar to yours. Here is my current power output. I removed some turns on the 40m and 20m toroids. 160m - 6.0 W 80m - 5.3 W 60m - 4.9 W 40m - 4.9 W 30m - 4.5 W 20m - 4.6

The non-inverting inputs of IC404 must be at AC ground for ANY frequencies presented at these points. As Stan and others have pointed out, these inputs are very sensitive to even the slightest

Thanks to all - the factory reset seemed to have done the trick. Now to do the alignment. 73 Ron AC2C

Are the BS170's installed?? I assume they are not blown if you have not yet finished building the transmitter part of the board, but there could be a solder glob from drain to ground somewhere. Is

The center tap position of T501 should not be shorted to ground, before or after installation of the transformer.? It should only be connected to the hole for one of the L502 wires (the one marked as

GM Stan, i lifted D109 and no change.? I re-soldered successfully using part of a discarded lead, and DMM tests are as prior. The most i get from Vcc and Vdd (at JP105) is 5-10mV, which holds as i

A separate container of flux is useful, sometimes you just want the solder to flow better but don't want to add a big glob of additional solder.? Here's a quick guide to various fluxes, I'd stick

I do not know, yet, how different boards align with each other. So I was afraid to take up the space that may make it difficult for other pieces to fit in. The solder I use is of a brand called

Getting ready to wind T501 on a revision 1 QMX+ I picked up at FDIM earlier this year.? I'm checking ahead on the steps to wind T501 based on page 26 and 27 of the manual, plus using the info for

Hello Bekir As Jerry said, there's no need to try to clean out the holes, particularly the grounded ones are very difficult indeed to clean. Just solder to the pads on top, and let the through hole

I work dozens of POTA stations with my EFHW up twenty feet. Mostly on 20. Mike Krieger [email protected]> wrote: