Kudos to CQ-DL!
I e-mailed them yesterday to buy a copy of the May 2009 issue of CQ-DL
Magazine .
Instead I found this morning in my mailbox an e-mail with a pdf of the
article - no charge!
Many thanks again to CQ-DL!
Angel Vilaseca HB9SLV
Felipe Ceglia - PY1NB a écrit :
> 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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>>
>
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