1. BITX20@groups.io

Re: Question about power output #ubitx #v5

Jerry Gaffke
 

Firmware for a v3 or v4 board mistakenly installed on a v5 or v6
would seriously attenuate 80 and 40 meters, but 10 and 20 meters should be unaffected.
Operation on 80 and 40 would be as if the antenna was disconnected, might damage the IRF510's.

Firmware for v5 or v6 on a v3 or v4 board would allow harmonics out on 80 and 40 meters
since only the 30m filter would be getting used, but again 20 and 10 meters are unaffected

Here's what the routine setTXFilters() does in the firmware for v3,v4 and v5,v6 boards:
                        30m   20m   40m   80m
ver 3,4:   abc = 000    100    110    111        (a=0 for 30m, else b=0 for 20m,  else c selects 80m not 40m)
ver 5,6:   abc = 000    100    010    001       (1 to engage each filter for 20m,40m,80m,  but 30m is always inline)
 
To get the symptoms reported (particularly an attenuated 20m) would require two different problems
out in the LPF's.   Possible, but seems more likely to be trouble further back in the power amp somewhere.

He reports that CW transmissions are also affected, so not an issue of anything prior to the first mixer at D1,D2.

Jerry, KE7ER


On Wed, Jan 15, 2020 at 06:38 AM, Gary Anderson wrote:
Simple question:
Are you using the factory V5 firmware?  Confirmed that your board is a V5?

With board changes from V3/4 to V5 the BFO and filter circuits changed.
I haven't gone through the logic mapping of what exactly would happen on the LPF circuits if the wrong version of firmware is used, but it will be problematic.
Join BITX20@groups.io to automatically receive all group messages.