[Amps] Tube swap

[Carl]

While the 211 is rated at full power to only 15 mc they were used 
industrially in pulse service at 50 mc according to Tube Lore.
I would expect the parasitic to be below that frequency or it was actually 
used (-;

Carl
KM1H
----- Original Message ----- 
From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
To: "Vic Rosenthal K2VCO" <k2vco.vic at gmail.com>; <amps at contesting.com>
Sent: Wednesday, January 29, 2014 10:35 PM
Subject: Re: [Amps] Tube swap


>  Use a pair of 211 tube and you will not need a parasitic suppressor.
> 73
> Bill wa4alv
>
> ________________________________________
> From: Amps [amps-bounces at contesting.com] on behalf of Vic Rosenthal K2VCO 
> [k2vco.vic at gmail.com]
> Sent: Wednesday, January 29, 2014 10:32 PM
> To: amps at contesting.com
> Subject: Re: [Amps] Tube swap
>
> The AADE meter cannot measure the stray inductance of a resistor. From
> the instruction manual: "Inductors must have a reasonable Q for their
> value and negligible distributed capacitance for their value." A
> resistor has very low Q!
>
> It also has trouble with large tubing coils due to the distributed
> capacitance. And it is not good for toroids on cores where the
> permeability varies with frequency.
>
> Given those limitations, the AADE meter can be very useful.
>
> On 1/29/2014 6:01 PM, William Turner wrote:
>> Please keep in mind two things:
>>
>> 1. The AADE meter measures inductance at a very low frequency. At VHF
>> the inductance can be considerably different due to distributed
>> capacitance between windings. The best tool is an impedance analyzer
>> which applies the actual VHF frequency and costs about $10k. I don't
>> have one either. It was that or a house.  :-)
>>
>> 2.  There is no such thing as "non-inductive". Even a short straight
>> piece of wire has inductance. If someone tells you a resistor is
>> non-inductive, they are prevaricating.
>>
>> 73, Bill W6WRT
>>
>>
>> ------------ ORIGINAL MESSAGE ------------
>>
>> On 1/29/2014 5:31 PM, Bryan Swadener wrote:
>>> I measured new Ohmite pn OY470KE (47ohm/2W) resistors at 1.6uH
>>> inductance.
>>> The instrument used was a new factory-assembled and calibrated
>>> "Almost All Digital Electronics" L-C Meter (http://www.aade.com/).
>>> According
>>> to the manufacturer, it compares closely to several high-end L/C/R
>>> instruments.  I verified mine, compared to a few other pieces of HP
>>> gear that
>>> I trust.
>>> Before making any measurements, I first nulled the internal inductance
>>> with the terminals shorted, using a 1" length of 14ga wire (about 17nH).
>>> A NOS Allen-Bradley 47 ohm/2W carbon composition resistor then
>>> measured 20nH, and a 3-1/2 turn 14ga parasitic suppressor inductor
>>> (Heathkit SB-220) measured 80nH. The OY "resistor" measured 1.58uH.
>>> The datasheet for the Ohmite OX/OY resistors
>>> (http://www.ohmite.com/cat/res_ox_oy.pdf) says only:
>>>
>>> "The OX/OY resistors can often replace carbon composition resistors
>>> which can be difficult to source."
>>>
>>> They make NO claim that they are without inductance.  In fact,
>>> nowhere in the datasheet is the word "inductance" or "reactance"
>>> used, or inferred.
>>> eBay seller "bigsmythe74" always seems to have
>>> A-B Carbon Composition resistors available for reasonable prices.
>>> I have no connection with him other than as a customer.
>>> vy 73,
>>> Bryan WA7PRC
>
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
>
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