Message-ID: <1608dcf5b07.marcocadeddu@tin.it>
Date: Mon, 25 Dec 2017 14:14:24 +0100 (CET)
From: "marcocadeddu@tin.it" <marcocadeddu@tin.it>
To:  <rsgb_lf_group@blacksheep.org>
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Subject: R: Re: R: Re: LF: TXing 2200m WSPR
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Hi Paul,

I guess that this is part of the play! When I had my first (analogic) 
multimeter I was sure it was something stolen from heaven.. I was 
looking also to parallax in order to read even the not readable :-))
Then with the years I added in my shack more measuring devices and time 
of doubts started!
Was is reading this meter?? Vpk, Vpp, Vrms Vxxxxx?
With the age I'm now more confident in what I measure after speding 
some time comparing the measures of different "tools" understanding 
what they were doing and veryfing if they were tuned with the theory 
and how much "serious" were my measures.
I remember once testing my first LF PA, I thought to be close to win a 
Nobel prize: my PA was putting out about 50% more than the DC input! :-
)))
So never mind or be descouraged in Italian we say that troubles are the 
salt of life ;-) if everything runs at the first attempt you miss a 
lot! ;-)
Hope you will be able to find the culprit in your work and then you 
will enjoy a lot of reports.

CU, Marco IK1HSS
----Messaggio originale----
Da: paul@n1bug.com
Data: 25-dic-2017 13.14
A: <rsgb_lf_group@blacksheep.org>
Ogg: Re: R: Re: LF: TXing 2200m WSPR

Hi Marco,

I don't detect any heat in the LPF but at this low power level it 
could be difficult to detect it.

I already have plans to build the big T type LPF. I have the 
T-225A-2 cores and metal to make a compartmented box. Capacitors are 
on the way, could arrive around 29 December. I still need to order 
the wire and some kind of material for mounting the big inductors.

I'm making that LPF because eventually I will also build the big 
amplifier. I'm not sure when that will happen, probably a bit late 
for this LF season.

The most curious thing is what seems to be some measurement error or 
impedance transformation but the cause remains elusive. I hope to 
find the reason so I can be more confident about measurements when I 
go go high power.

73,
Paul N1BUG


On 12/25/2017 04:35 AM, marcocadeddu@tin.it wrote:
> Hello everybody,
> 
> it's ever interesting to read that somebody else has some troubles as
> experienced from myself ;-)
> Me too am grateful to Andy for the support I received
> while struggling with odd experiences..
> Let me join the discussion and share a possible solution: I see that
> LPF is a PI version, similar to what I used in the past. It was nice 
in
> RL, armonic suppression and losses when tested with low power
> instruments, than I was increasing the wire diameter of coils because
> it was a... warming thing! The current was indeed very high in the 
FETs
> (2+2 FETs in push pull) and the RIP area was growing...
> After I tried the T LPF (see attachment) no more problems, no more
> warming boxes..
> You could re-arrange your LPF components for a quick trial and save
> some caps ;-)
> In my version I had to make some change because the cores were not
> available and used T200-A2 cores calculating the turns to get 59 and
> 109 uH coils.
> 
> Maybe it's worth to try ;-)
> 
> CU on 137kHz
> 
> Marco, IK1HSS