Message-ID: <1621f5d38b9.marcocadeddu@tin.it>
Date: Tue, 13 Mar 2018 13:37:05 +0100 (CET)
From: "marcocadeddu@tin.it" <marcocadeddu@tin.it>
To:  <rsgb_lf_group@blacksheep.org>
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Subject: R: RE: LF: LU1DOW soon in MF/LF
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Hi Luis, Chris and LF,

enjoyed the pictures from Oscar.. when I see tubes my heart..
I don't wonder for the filament current (at 5V it means 150W) but how 
Oscar arranged the PI or PL output matching circuit: I guess he 
modified an HF PA and it means a lot of L and C to retune from 160m..

Hope to hear soon Oscar on LF/MF.

Now I'm testing the new TX for MF it is on since last saturday 24h/24h 
trasmitting WSPR2 every 10 minutes.
I need some fine (at least dry..) weather to tune and match better the 
antenna because now the return loss is not really wonderful (almost 10 
dB..) so I haven't any idea of the ERP but it should be in the range of 
200mW.

Enjoy MF/LF and lower ;-)

73, Marco IK1HSS
----Messaggio originale----
Da: luis@vigilant.es
Data: 13-mar-2018 11.28
A: "rsgb_lf_group@blacksheep.org"<rsgb_lf_group@blacksheep.org>
Ogg: RE: LF: LU1DOW soon in MF/LF

Hi Chris, LF

Oscar answered the question. I'll try to translate, but can't promise 
not to make a mistake in tube terminology :-)

He is not using filament choke as this is a direct heating tethrode. So 
the midpoint of the filament transformer secondary is connected to 
ground
The driving is to the grid with a tuned circuit. It works in C class 
for QRSS and B Class for DFCW. And YES, this a dangerous high voltage 
bricolage
and a waste of energy. Just the filament is sucking 35.5 Amps :-O

Oscar plans to test first single carrier in LF with LU8YD at 1000Km 
first to check if all is going as in previous tests some time ago. 
After that he will switch
to MF and test again

73 de Luis
EA5DOM