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Probably a early form of Spread
Spectrum , hard to JAM if is its
jumping about the band and difficult
to make a fake transmission if the Tx has a
wobbly bob signature : )
G..
Sent: Wednesday, December 19, 2012 5:42 PM
Subject: Re: LF: Better picture of the 807 based 500kHz
TX
OK Mal
Point taken. I was referring
to a "Power" oscillator like a single 6L6 used as an Xtal oscillator running at 15 / 20Watts which means
normally there is insufficient
current (really) from a VR tube for the
Anode(plate) so all that is necessary is to stab the screen. Otherwise I totally
agree.
I do know the standard T1154 chirps well. There is a PA0 who runs one
on 500 and I am sure you have worked him it is like a signature signal
HI.
I think there was some kind unpleasantness going on at the time of the
T1154 manufacture so the fine points of frequency control was probably
a low priority.
73 es GL Pete M0FMT IO91 UX
Hi Pete
Stabilise both Plate es Screen on an Oscillator,
followed by a Cathode follower to avoid chirp and osc pulling.
The T1154 was very unstable with a bad chirp, surprised
it ever passed Quality Control
G3KEV
-----
Original Message -----
Sent:
Wednesday, December 19, 2012 10:08 AM
Subject:
Fw: LF: Better picture of the 807
based 500kHz TX
Try again minus cct too
big I think.
73 es GL Pete M0FMT IO91 UX
Hi Dimitris and group
I have not seen the schematic but it is usual to stabilise the
screen of a power oscillator to reduce chirp on key down.
Now you have shown us yours I will show you mine. I usually
sketch the schamatic after the
event so foregive the presentation
on the back of an envelope.
I now get at least 4Watts after adjusting the ant link coupling
away from the chasis. Best audible
DX Kent 80miles best Opera DX PA0 land.
73 es GL Pete M0FMT IO91 UX
2012/12/19 Graham < [email protected]>: >
Why the stabilised screen supply ? >
G.. It's embarassing. I
like the glow of VR tubes!
:-) 73, Dimitris VK1 SV
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