Hi folks,
I don't want to nag, but I'm just
completely stranded and would highly appreciate some hint, as
where to take things up from here. I simply just got no clue what
do do now or try next at best ... and I do not want to further
worsen things.
From a problem on 20/30m (of course
it's a low-band QMX), I ran into trouble on all bands 80-20 now,
see quotes from my to posts below.
And in case if I've violated some
internal protocol here on the list by my posts, please let me know
(that I might learn), instead of not replying at all. - Thank you
all!
Am 07.01.24 um 16:04 schrieb Stefan U.
Hegner:
Am 30.12.23 um 20:47 schrieb Stefan
U. Hegner:
For the 20/30 m bands I have (with dummy load attached):
- an Audio Filter Sweep with the yellow USB at -45/-51 db
and the red LSB at ~-70db
- an RF Filter Sweep with -43/-52 db at the center band
- an SWR sweep jumping wildly around between? 2 and 10
(whereas the other bands are at 1 - 1.2)
Sounds to me like some LPF Problem on 20/30m regarding L510
& L513, or is this rather an issue with the wired back
jumper of L401 23t to 23t holes (I did not do this with a
cut-off but with the overlength of the AWG28 wire.)? Or does
this hint to something else
I thought, this would be a pretty staight forward problem to be
solved with re-soldering the toroids ... well, this is
apparently not so and I have probably made things worse ... but
I do not know where to start now. The solder joints look fine to
me in daylight under a magnifying glass.
Current diagnostics with a dummy load are as follows:
- The yellow USB values for the audio filter sweep ar now
between -56 and -41 for all bands.?
- RF filter sweep is between -42 and? -56 for all
bands
- SWR sweep is at around 1.1/1.2 ... however for 40m and 20m
bands it jumps erratically between 1 and 10 over the spectrum
- that's strange, as there are to my mind no parts of the
circuit that are used for these two bands only.
To me that seems, that there is something buggered up in
general in the RF-signal-line.
Whrere should I start now?
- L401 BPF?
- with the trifiliar T401?
- I do not think, that my issues have to do with the PA and
T501 / L502, because that would mean trouble on transmit, and
to my mind the PA isn't powerd up for the internal
diagnostics.?
Further I suspect, it does only make sense to go back to the
LPFs by band, once the general issue has been fixed. - Or am I
totally mistaken on this approach?
In general, this time I tried Hans' approach for the
de-enameling the AWG22 wire with the wire cutters. - Maybe I was
to fearful at this end and hence the connections are not so
good. - That's also why I am a bit nervous on the PA side ...
Any suggestions are highly welcome and very much appreciated!
Have a nice day and Vy73
Stefan.
--
Stefan U. Hegner <db4st@...>
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