If you have a dummy load connected, as you should, then you will see 50 ohms. The 104 capacitor check makes Q1-3 failure likely. 73 Alan G4ZFQ

There should be no DC path to ground in the low pass filter, as the RF caps should be many megohms to DC. In vacuum tube output circuits, particularly PI tank circuits, an RF choke was always included

I constructed my 50 W amplifier For 20 M at the end of June, and the assembly process went well. I set the bias for 113 mA with A 20.1 V power supply, no RF power input, and both the input and output

There does appear to be a path to ground through the LPF, however, It's not a dead short, and appears to be through a capacitor, which is to be expected? C29 appears to be working fine as far as i can

I dont know if there is RF , but I'm reading 11.97v (external meter) at the non-lpf side of c29, then 7v on the other side. Interestingly, there always seems to be ~4.7v at the rf output, unless its

Hi, QCZ+ 700 hz tone in BPF peak is very weak, also IO screen is jumping? Checked toroid connections and resoldered.

First limiting factor is caps with 50V rating. That can tolerate 20W but only if the SWR is under 2:1. Bump up to 100V parts and you in the comfortable 25-30W level. More than that 200V or higher.

Thank you for this answer, W4JED. That's a point that a lot of us missed; we were assuming there is actually RF on the non-LPF side of C29. The suggestions people (including me!) have been making

Mates: I have the following for sale. 99 percent assembled but never powered up or aligned. Just don't have time for it. SO here is what I have: U3s - Rev 3 F/W 3.12 GPS QLG1 Relay LPF board LPF for

Jim, good information. Thanks... Jim...kq3s

You should read again John...copied and pasted from the assembly instructions. Cheers Vernon

Hi John: No that is wrong. Highest band goes in position 1. Read the manual carefully. Regards Roger G3YTN --- *************************** Roger Hill ***************************

From what I read in my build instructions, position 0 must have the highest band module. In my case 10M (28Mhz).

I agree with Curt that the built-in bar graph works very well, but the auto-scaling can be a bit distracting. as an alternative, I've found that simply listening with a decent pair of headphones

Hi Ken Thanks for your suggestion..... I monitored the 5 v line and I don't think it is dipping. I think what I am going to do is order another relay board kit..... I am starting to think I have some

PUH-LEEZE!! When applied to a point with a DC voltage, the "wattmeter" reads the DC as "watts". Any DC voltage above a certain level (Hans could probably tell you what that level is) is

Phil Tim in ZL back again. As far as the OPT is concerned , I have had a look at optimising it at 80 Mhz as a half way house between 6m and 2m. Type 43 material as per previous is death to RF at

Hello Hans and all, what would you think of a QRPLabs "Transmitter Module"? Counterpart of the Receiver Module and a QSX spin-off. We could combine the VFO Module, the Receiver Module, said

There are three things that can limit the power handling of a filter: 1. Voltage rating of the capacitors 2. Saturation and heating of the cores 3. Resistive heating of the wire used to wind the

The problem is that the on-board power meter does not necessarily show RF here. DC voltage will affect this and make you think there is RF there. Connect one end of your 104 capacitor to the input end