Re: Failure to get a sufficiently high BPF Peak #qcx #bpf #alignment #40m

Hans Summers
 

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 the receiver. The other alignment menu tools "8.8 I-Q bal", "8.9 Phase Lo" and "8.10 Phase Hi" are sampled from Audio1 which does come AFTER the volume control and therefore the volume control setting does affect the reading on screen. This is because the further gain was needed for unwanted sideband measurement, since the signals are up to 60dB or more weaker after good cancellation. 

The fact that you have any BPF reading at all seems to indicate that at least something is working as it should be. The low reading could be due to:
  • Non resonant BPF tank circuit in T1... possibly due to incorrect number of turns. We do not usually find it necessary to adjust the number of turns on the long winding, however. You did not mention which band you built - for 40/30/20/17 band versions I think the trimmer capacitor range is normally enough and you should not need to mess with the number of turns. 
  • Mis-soldered wires around T1... either wires in the wrong holes, or wires not soldered properly because the enamel wasn't burned off. Does turning the trimmer C1 have any effect? If not, then this could indicate the wires of the long winding are not soldered properly, and therefore there is no electrical connection. Be particularly careful with soldering wires which are grounded, because the ground plane tends to suck away the heat and make a good clean joint less easy to achieve. 
  • When you have the volume set to around mid-range and you turn the rotary encoder from "8.7 Peak BPF" to "8.8 I-Q Bal" the tone will usually get significantly quieter (in 8.8). If it does not, you might have a fault in one of the signal paths I and Q, around IC5/6/7 that is preventing cancellation. That would also prevent addition of the in-phase signals of the wanted sideband, therefore lowering volume. 
73 Hans G0UPL





On Tue, Nov 19, 2019 at 1:01 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
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
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