>Thanks for taking the time to respond to my question
>Rich.
>My ZSAC is 180ma for the two 3-400Z tubes and that is
>what Swan recommends in the amp's manual. This is at
>about 2500 vdc. With or without the diodes the ZSAC
>it is still 180ma. The diodes have made no difference
>in the resting plate current.
No difference means there may be a miswire because each diode makes c.
0.7v drop and even 0.7v should noticably change the ZSAC.
- note -- The diode string needs to connect between the fil CT and the
jucntion of the anode current and the grid current meter shunt resistors.
The T/R bias switch goes in series with either end of the diode string.
cheerz, Bill
>--- Richard <2@mail.vcnet.com> wrote:
>>
>>
>> >It has been suggested I add a string of diodes in
>> the
>> >center tap of the Filament Transformer in my Swan
>> Mark
>> >1 amplifier for bias. This is a Zero Bias amp but
>> >bias is suggested anyway to ensure a stable bias
>> >voltage. The tubes in use are a pair of 3-400Z
>> tubes
>> >in GG.
>>
>> 3-400Zs have a Mu of c. 190. They have a ZSAC of c.
>> 80mA each at 3kVDC
>> and 0V g-fil bias. Less ZSAC is ok for CW, but not
>> ok for SSB.
>> >
>> >I like to gather a variety of opinions on questions
>> >like this because I learn so much from the various
>> >opinions.
>> >73,
>> >Bill
>> >
>> >=====
>> >Bill Smith KO4NR
>> >
>> >__________________________________________________
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>> >
>>
>>
>> - R. L. Measures, a.k.a. Rich...,
>> 805.386.3734,AG6K,
>> www.vcnet.com/measures.
>> end
>>
>
>
>=====
>Bill Smith KO4NR
>
>__________________________________________________
>Do You Yahoo!?
>Sign up for SBC Yahoo! Dial - First Month Free
>http://sbc.yahoo.com
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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