>
>
> Well, let´s stick to the QBL5/3500 or let´s try to find another tube
> that might work in DAF configuration.
[chortle]
>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.
Say what?
> 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.
Who is we? Do you have a mouse in your pocket? The 8660/4CX1500B is
designed to operate with grid-current. Why would it not work in DAF
service?
> By the way, talking about splatter, Yesterday on 21 MHz I heard
> a USA station that was 50 kHz wide.
50kHz is Small potatoes. W6CHR splattered well over 100KHz with his DAF
amp.
> 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?
>
A radio homing cruise missile?
later, Jim--------------------
>
>-----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.
......
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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