Mr. Summers, Thank you for the response. We are building the 40 band version. The C1 tuning trimmer does have an effect on the BPF reading so we are getting some form of electrical connectivity throug

#alignment #qcx #bpf #40m

Hi William, all: A minor point: BPF peaking 8.7 does not depend on the volume control setting. This is because it is sampled from Audio2, which is BEFORE the volume control in the signal path through

#alignment #qcx #bpf #40m

I will rephrase the earlier as it maybe unclear to a new user. The level display on the LCD is relative to the volume control. Set if for some level in the middle of range then try to peak it. Allison

#alignment #qcx #bpf #40m

Where is the volume control set? Check the connectivity of all the T1 windings using the solder pad as the test point ( not the end of the wire). Many times issues with the peaking ins due to poor sol

#alignment #qcx #bpf #40m

One thing you might want to consider doing first is to check continuity through the lowpass filter. This can be done by checking from the center pin of the BNC connector to junction of L3 and C27. If

#alignment #qcx #bpf #40m

Thank you sir! We will try this out first thing in the morning. I do believe that we have access to LCR meter.

#alignment #qcx #bpf #40m

Hi If you have access to an LCR meter I suggest you measure the toroid windings. I’ve built one (QCX40) and I had to take off a couple of turns. From my notes I reckoned it was around 0.1uH/turn. It a

#alignment #qcx #bpf #40m

Hello and greetings, My name is Will Wallace and my class mate Joe Corbin and I are building the QRP Labs QCX 5W CW Transceiver as a part of a class. We are both students studying engineering at Ottaw

#alignment #qcx #bpf #40m

For info, atmospheric noise in a 2.5Khz window on 80m is about -100dbm or -111dbm in a CW window. At 28Mhz that becomes -120dbm and -130dbm. I think most rx's have more than enough gain to compensate

#bpf

Hi Jack The 80m filter has plenty of bandwidth to cover the whole band. If you do happen to want it wider this can be achieved by using a slightly larger coupling capacitor between the two tuned circu

#bpf

Hi Jack. According to the specifications on this filter, it has a 3 dB bandwidth of 465 kHz on 80 meters. You should be able to see from the digital segment to the AM segment with no more than 3 dB ad

#bpf

I am considering building a 10 band BPF filter set to function as front end filtering for an Afedri SDR. The filters all look good for this purpose except the 80M filter which appears to run out of ba

#bpf

Hi, I managed to assemble my QCX 20m a few weekends ago. It all went together well following the build instructions. The alignment however was another story, all booted up fine on power on. relevant m

#alignment #bpf

I managed to attach and get the connection under the toroid, so I think I'm alright adding the turns. I'll try that tonight. If that doesn't work, I have several values of NP0 that I've been collectin

#qcx #alignment #bpf

Hi, Bill Sorry to rain on your parade, but if peak comes at full mesh of C1, that means you are using the capacitor to compensate for insufficient inductance. You need to either (a) add turns (which e

#qcx #alignment #bpf

on another reading of the manual, I seem to have misread it. Rats. OK, I'll have to add some wire to the winding, in addition to what I removed. I'll check C5 while I'm at it. Thanks!

#qcx #alignment #bpf

Fully meshed C1 would seem to indicate too low inductance on S3. Removing turns is the wrong way to go. Are you sure C5 is correct value? I.e. not too small?

#qcx #alignment #bpf

I've completed a 40M QCX (built the 20M last year). Doing the BPF alignment, I could only get max signal with C1 nearly fully meshed (at a power of 10), so I removed 5 turns from T1 (which was easier

#qcx #alignment #bpf

Hi All, T1: Regarding my previous posting on the winding of T1 using a FT37-43 instead of the T50, one may ask what advantages were gained by changing the original winding scheme and the BPF being mad

#t1 #qcx #bpf

Hi Hans and John, Thanks for the info. The QCX is an excellent design. I just wanted to try out a simple broad-band transformer on performance and avoid making another T1 with more turns than before u

#t1 #qcx #bpf