Hi Angel,
I one recent CQ DL magazine, may 2009 (the one with the CW op YL on
cover), there is a project for a funf-tube PL519 amplifier. If I recall
it correctly it does not use a HV trafo, but for sure the output tank
was PI.
If anyone have any information about the Fuchreis tuning network, I
would like to hear about it.
73,
Felipe - PY1NB
Angel Vilaseca wrote:
> Gentlemen,
>
> I just bought an old amp that uses 5 PL 519 TV sweep tubes in parallel.
> As it reads on the box, it was home made on June 1983 by HB9 AWI.
> The amp does not work anymore, but it is superbly built. The builder,
> HB9AWI, obviously put a lot of effort into it.
>
> I would like to restore it. It is so well made and so typical of ham
> state of the art at the end of last Century.
> No inexpensive Russian power tubes were obtainable at these cold war
> times! On the other hand, old color TV sets with sweep tubes still alive
> were plentiful. The PL519 had the reputation of being quite rugged. Most
> frequently, it was the line output power treansformer of the TV set that
> failed, not the tube.
>
> Unfortunately, there was no schematic included with the amp..
>
> The seller told me the design of the circuit was by DL9AH. It is quite a
> non-typical design:
> For one, the tank circuit is not a Pi, nor a Pi-L! It is called a
> Fuchkreis. It seems it was invented by an Austrian ham called Fuchs. I
> never saw anything like it.
> The power supply is a transformerless design. Apparently, it delivers +
> and - 300 Volts. So needless to say, the cathode circuit of the five
> PL519s is quite unconventional too. The bias circuit uses two pentodes,
> a PL 504 (a b&w TV sweep tube) and a smaller one. Never saw anything
> like this either!
> There is a separate 10-turn potentiometer for each PL519 to adjust the
> current through each tube. Quite sensible when you use five second-hand
> tubes, that may have already lived a number of years as sweep tubes in
> TV-sets.
> The power supply, the bias circuit, the relays circuit all have lots of
> VK200s and decoupling caps everywhere.
>
> As I just said, in a true ham spirit, it may use cheap tubes, but
> obviously a lot of care was used to design and build this piece of
> equipment.
>
> So, really, I would like to restore it. I tried finding the DL9AH design
> on the web, but no luck!
>
> Does the phrase " Sweep tube amp, DL9AH design" ring a bell? Especially
> for european hams?
>
> Any information about the design, or schematic welcome.
>
> Vy 73
>
> Angel Vilaseca HB9SLV
>
>
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>
--
Felipe Ceglia - PY1NB
-------------------------------------------------------------------------------------
PR1T team member /// Rio DX Group member /// Araucaria DX Group member
http://www.dxwatch.com /// http://reversebeacon.net ///
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