The impedance of an inductor with a resistance in series, is equivalent to
another inductor with a certain resistance in parallel.
This is easily demonstrable by impedance series parallel transformations and
shouldn't start another debate but's helpful to point out that overall
circuit response is what counts and not single devices.
A coil made with a bad conductor may be electrically equivalent to an
inductor made with highest conductivity material but with a resistor across.
If an inductor uses a material whose losses may change with frequency, a low
loss coil with a resistor in parallel is same complex to predict because
resistor terminals (series inductance) and physical dimension (stray
capacitance) influence the overall impedance and Q, not counting other
problems like resistor failures or resistivity variations due to
overheating.
If an amplifier has a proper layout and tube, any suppressor solution is
applicable (mostly because not strictly needed).
If an amplifier hasn't a proper layout and tube (parasitics are closer to
amplified bands), everything is quite critical and a practical suppressor
may not exist at all.
73
Mauri I4JMY
----- Original Message -----
From: "Michael Tope" <W4EF@dellroy.com>
To: "measures" <2@vc.net>; "AMPS" <amps@contesting.com>
Sent: Saturday, October 14, 2000 5:50 PM
Subject: Re: [AMPS] a sticky issue.
>
> Rich,
>
> Seems that issue is not that effective resistivity of nichrome increases
> with decreasing frequency - I don't think anybody is arguing that. What
> is evident is that the effective series resistance of the nichrome
suppressor
> is higher than conventional suppressor at low frequencies. From what I
> can see, this seems to be the basic tradeoff between the nichrome
suppressors
> and the conventional suppressors. If I am recalling the test data
correctly,
> the nichrome suppressor has higher losses at moderate VHF frequencies
> (50 to 100 MHz) - a good thing, at the expense of higher losses in the HF
> frequency range (a bad thing). As the frequency increases further the
> the two suppressors start to converge as the inductive reactance of the
> nichrome suppressor starts to dominate over the resistance of the wire.
> No rocket science here.
>
> Mike, W4EF...................................
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