[Milsurplus] More Fun with BC-230 - 30 Meters

[Richard]

Good point.  The only problem I've had was paralleling tubes.  Once I 
had an experimental MF transmitter with a 211 in the final, and when I 
tried to parallel another one had a vicious VHF parasitic between tubes.

Richard, AA1P

On 08/03/2014 12:32 PM, Brian Carling wrote:
> I love beam power tubes. I never have any difficulty with self oscillation problems. On the other hand TRIODES in common cathode circuits can sometimes be almost untamable.
>
> Prime example:
> Pair of V70D tubes in the RF final of the Globe King 400 transmitter.
>
> Best regards - Bry Carling
>
>
>
>> On Aug 3, 2014, at 10:53 AM, Richard <brunneraa1p at comcast.net> wrote:
>>
>> About the 5763:  See "Intrinsic Negative Resistance as a Cause of Parasitic Oscillations in Beam Power Tubes," by David Newkirk," for more than you want to know.  The 5763 is an exemplary example, and "may" be cured by adding a 100 Ohm non-inductive resistor between the screen terminal and bypass capacitor.  I personally practice Beam Power Tube Avoidance.
>>
>> Richard, AA1P
>>
>>> On 08/03/2014 07:48 AM, David Stinson wrote:
>>> While working on a way to get the BC-230 5-6 MC coil to
>>> scoot-up to 40 meters, I managed to booger-ize one of
>>> the PA Tank/Antenna coils.
>>> Rather than can it, I rewound it.  Used the BC-230 with
>>> the 6AQ5s  (have abandoned the 5763s- too hard to
>>> neutralize and de-FM).  Unwound the tinned coil wire,
>>> covered the thin, fragile link coil under it with a single layer
>>> of tape and used the tinned wire to wind a 12-turn tank coil.
>>> Yes; the wire's "lumpy" from being on that form.
>>> I'll rewind it with fresh wire later.
>>> Here's a crummy picture:
>>> http://home.netcom.com/~arc5/SCR-183/230-30m.jpg
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