[Amps] Anode Impedance of 4-400A

[R.Measures]

On Nov 16, 2005, at 7:11 AM, Peter Voelpel wrote:

> True, if grid current is allowed to run higher then 1mA,
> but these tube family is not built for AB1,

Eimac rates the 4-400A and 4-400C for Class AB1 linear service.  In my 
opinion, 800 screen volts and 4000 anode volts are about right.  With a 
50½ grid termination, neutralization should be optional.   Drive 
requirement with such would be c. 190W.

> I prefer to run them in highµ service anyway.

Grounded-grid is undoubtedly the universal cure-all for lack of 
linearity.
>
> 73
> Peter
>
> -----Original Message-----
> From: R. Measures [mailto:r at somis.org]
> Sent: Mittwoch, 16. November 2005 15:53
> To: Peter Voelpel
> Subject: Re: [Amps] Anode Impedance of 4-400A
>
> Class B anything produces much feculence in SSB service.
>
> On Nov 16, 2005, at 5:25 AM, Peter Voelpel wrote:
>
>> Those tubes will be rather used in class B.
>> Without grid-current they put out 1200W at 3,5KV anode voltage, with a
>> total of 13mA grid current it will be about 1600W.
>> On using the formula Ep/x*Ip one should consider that Ep will be
>> smaller then the supply voltage, as the voltage swing should not move
>> below the screeen voltage, in this case Ep will be 2,9KV for that
>> calculation
>>
>> 73
>> Peter
>>
>> -----Original Message-----
>> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
>> On
>> Behalf Of David C. Hallam
>> Sent: Mittwoch, 16. November 2005 02:05
>> To: Joe Subich, W4TV; 'Phil Clements'; Amps at contesting.com
>> Subject: Re: [Amps] Anode Impedance of 4-400A
>>
>> I think we are nit picking here since the original request was for an
>> approximation of Zp.
>>
>> However just to keep things going, I think a multiplier of 1.55/1.6
>> more closely approximates class A operation.  While AB1 indicates G1
>> will never be driven positive, in practice we generally come fairly
>> close looking for that last watt.  All the calculations I have done
>> with the constant current curves for power tubes in AB1 (admittedly
>> this is not vast numbers of calculations), the calculated Zp from the
>> curves equates to a multiplier of 1.8/1.9.  This is what you would
>> expect if you drive G1 close to 0 volts.
>>
>> David
>> KC2JD
>>
>> -----Original Message-----
>> From: amps-bounces at contesting.com
>> [mailto:amps-bounces at contesting.com]On
>> Behalf Of Joe Subich, W4TV
>> Sent: Tuesday, November 15, 2005 7:22 PM
>> To: 'Phil Clements'; Amps at contesting.com
>> Subject: Re: [Amps] Anode Impedance of 4-400A
>>
>>
>>
>> Phil,
>>
>> What class of operation, A, AB1, AB2, B or C and what conduction angle
>> if class C?  The 1.8 factor is an averaging factor based on conduction
>> angle.
>> For example, class A will be Ep/Ip while a single tube in class B will
>> be
>> Ep/(2*Ip) because the peak currents are twice the DC average due to
>> the 180 degree conduction angle.
>>
>> A typical tetrode amplifier will have a lower multiplication factor
>> since it will generally be operated in class AB1 (no grid current,
>> longer conduction angle), while most triodes in grounded grid will
>> have a higher multiplication factor due to the lower conduction angle
>> (closer to class B).
>>
>> To simply use 1.8 is close but if the 4-400A is being used as a
>> tetrode and grid driven, 1.8 will probably give too low a plate
>> impedance ... the multiplier for AB1 is closer to 1.55 or 1.6.
>>
>> 73,
>>
>>     ... Joe, W4TV
>>
>>
>>
>>> -----Original Message-----
>>> From: amps-bounces at contesting.com
>>> [mailto:amps-bounces at contesting.com] On Behalf Of Phil Clements
>>> Sent: Tuesday, November 15, 2005 6:40 PM
>>> To: 'Patti'; amps at contesting.com
>>> Subject: Re: [Amps] Anode Impedance of 4-400A
>>>
>>>
>>> The load impedance of any tube or group of tubes is anode voltage
>>> under load divided by total anode current times 1.8.
>>> It matters not what the type or brand of the tube(s) are. A single
>>> 8877 amp that has 4000 volts on the anode and an anode current of 1
>>> amp will have a plate load impedance of 2222 ohms.
>>>
>>> (((73)))
>>> Phil, K5PC
>>>
>>>
>>>  Subject: [Amps] Anode Impedance of 4-400A
>>>>
>>>> Does anyone know the 'rough' load impedance of a pair of
>>> 4-400A's with
>>>> 3500V on the anode?
>>>>
>>>> In some of EIMAC literature (W6SAI AS-1 Publication), there
>>> are tables,
>>>> which list it as 5000 Ohms.  Is this for one tube, or two?
>>>>
>>>> The 1982 ARRL Handbook contains a design with a pair.  The
>>> PI network
>>>> values listed there, equate to a load of 5000 Ohms, with a
>>> Q of about 12.
>>>>
>>>>
>>>> I am just trying to cross a few items off of my list.
>>>> If someone can contact me off list, I would appreciate it.
>>>>
>>>> Thanks
>>>> Eric Thielking
>>>
>>>
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>>>
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>
> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>
>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org