Jan,
Your comments about Kris KG2BU (SP) are of no surprise to me, we in the
New York region have know about him and his "Mighty Killer Amplifier" for
some time and if you think that he is 50 kHz wide on 21 MHz the you
missed him on 75 meters at lest 75 kHz wide if not more.
Yes it is a GU84 Amp built by a SP Ham in what I believe is the city of
Radom and yes using that valve.
KG2BU some how smuggled this Amplifier into the states, I had a quick
look at it some time back when KG2BU got it was not in hiding from his
fellow country men in New York.
The Amp in Question is a very Primitive Design (minimal input -anything)
executed in a desktop format with a poor power supply, but the main
problem is the operator who lacks the basic skills of even understanding
basic amplifier theory and operations and even lacks the simplistic
knowledge of proper tune- up his idea is for MAX POWER .
And if you think that his signal is bad now, to bad you did not hear him
on his 746 when he had a power supply (Icom) that had more switching hash
on it then "voice"audio
You are right he states to all "So what I have the strongest signal on
the band" and to H.... wit you..all in Polish.
And the local OO are somehow always someplace else.
To bad becouse the GU-84 is a fine "valve" and I have built one nice Amp
using it and just finished re-tubing a Henry basket case with one
(works like a charm) and the "valve" and socket only cost me $85 .
73's
Steve
AB2ET
On Mon, 20 Mar 2000 07:29:53 +0100 Jan.E.Holm@telia.se writes:
>
>
> Well, let´s stick to the QBL5/3500 or let´s try to find another
> tube
> that might work in DAF configuration. In my book I consider the
> QBL quite ok in DAF as I stated before, based upon several amps
> that I have heard on the air that has the correct bandwith for
> SSB.
> Maybe some other tube used in the television service might be
> sutable, they need very linear and low distortion stuff for TV
> service.
> There are off course the Thompson tubes, TH328 and TH338 but
> they like the 8877 zero mA grid current fuses. There are also
> bigger
> Thompsons used like the TH347 but I don´t have any data in my
> head right now. So let´s rule the 4CX250´s 813´s 4CX1500 out
> since
> we pritty much understand that they don´t work in G2DAF.
> By the way, talking about splatter, Yesterday on 21 MHz I heard
> a USA station that was 50 kHz wide. He had monster splatter and
> wasn´t stronger then 15 - 20 dB over 9. He was runing a IC746
> and
> a amp with GU84´s ( I bet in class C). His call was KG2BU, did
> anyone
> of you guys hear him? I of course tried to tell him about his
> problem
> but all he responded was "I don´t care", so what to do?
>
> 73, Jim SM2EKM
> -----------------------------------
>
> -----Ursprungligt meddelande-----
> Från: 2@vc.net [SMTP:2@vc.net]
> Skickat: den 18 mars 2000 02:08
> Till: k7fm@teleport.com; Peter_Chadwick@mitel.com;
> amps@contesting.com; Jan.E.Holm@telia.se; W8JI@contesting.com
> Ämne: Re: [AMPS] Re: New G2DAF amplifier information
>
> >
> >Rich said:
> >
> >"Any guesses at to what would happen if a 8660/4CX1500B were used
> in a
> DAF
> >circuit. - with say 20mA of grid current instead of 0.06mA of grid
> current?"
> >
> >Rich:
> >
> >I have heard no one - except you - suggest using an 8660 in a DAF
> circuit.
> >Your friend, Norm, used 4CX250 tubes in a mis-understood bastard
> adaptation
> >of the original G2DAF circuit, which hung an electrolytic capacitor
> on
> the
> >screen grid. It splattered badly.
>
> Norm tried improving the original DAF circuit because it had a tad
> too
> much splatter.
>
> > It was not a G2DAF circuit. Yet, you
> >use it as a basis to condemn any reasoning that is not consistent
> with
> the
> >world as you view it.
>
> I was there. I got splattered on by the wonderful orig. DAF. I got
> splattered on by the modified DAF.
> >
> >Tubes do not have to be used as the tube manufacturer originally
> intended
> >them to be used, and amateurs by their very nature are
> experimenters.
> I
> >recently built an oscillator which used the screen as the plate.
> It
> works
> >fine. Tubes were not intended to be used that way. It is called a
> Dynatron
> >and was designed long before I was born (which is getting rare
> these
> days).
> >Building any circuit - "good" or "bad" - is fine, so long as the
> builder
> >makes sure he does not unreasonably splatter. Certain tube design
> >parameters must be met for the long term health of the tube.
> Beyond
> that,
> >the only other question is whether the output has undesireable
> >characteristics such as splatter, harmonics or parasitics. And, it
> is
> up to
> >the designer or builder to achieve those goals. It would be a
> boring
> world
> >if all the amplifiers looked exactly the same and used exactly the
> same
> >tube.
>
> Running a tetrode to minimize splatter is a piece of cake. Select
> one
> that can do AB1. (The 813 is not one of them). Use maximal
> regulated
> screen potential and anode supply volts. Adjust the bias so that
> there
> is no grid current with max. drive. Tweak the screen volts to set
> Zero
> Signal Anode Current (ZSAC). Tune/load for the recommended screen
> current. That's All, Folks.
> >
> >The other day, I raised the question of increasing the screen
> voltage
> on a
> >grounded grid tetrode - from zero to something less than the
> "normal"
> >voltage. Your response was "DAF circuits produce feculance".
>
> Did I not also point out that the power out with your stated screen
> potential was comparable to the power from the driver?.
>
> >The
> >"distortion" was in your response. I am sorry that Norm's
> splatter
> years
> >ago affected your outlook on life so much.
>
> The splatter from Norm's DAF amp was quite trival compared to
> W6CHR's.
>
> The first time I heard CHR put his DAF on the air, I was talking
> with a
> group at 3820KHz. We began hearing something that sounded sort of
> like
> splatter. I tuned my aux. Receiver around to various signals while
> listening for a match on 3820. I was surprised to find no matches
> within
> 25KHz . I had never heard such a thing before. Was I growing DAFt?
>
> The
> splatter sounded more like it was coming from above than below, so I
> tuned farther and farther up the band. I finally found the source
> on
> 3808. It was CHR He truly had a large signal. . Is this awesome
> or
> what?
> >
> cheers, Colin
>
> - Rich..., 805.386.3734, www.vcnet.com/measures.
> end
>
> <<Fil: Re_ [AMPS] Re_ New G2DAF amplifier information.TXT>>
>
>
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