>re: CTI screen regulator, tubes vs solid state
>-
>Remember the past posts on the CTI 4cx250b amplifiers
>using tube voltage regulators in the screen supply?
>The President Bob Piselli (wa1zru) Emailed the
>below text to me.
>-
>-
>[paste]
>... The reason I used gas regulators vs solid state, is
>the ability of gas regulators to have a longer time
>constant over the attack and release cycle of regulation.
* There is no attack and release in a shunt regulator. It's on 100% of
the time. The difference between gas tube regulation and zener-avalanche
diode regulation is that at turn-on, gas regulators require more
potential to begin conducting. The delta-current capability of gas
regulators is c. 30mA whereas zeners are capable of more delta-current.
For 4cx250Bs - which have minimal or even reverse screen current - gas
tubes work well but offer no performance edge over zener regulators
provided the zeners are operated under 1/3 of their surreal dissipation
rating. For example, it might seem thar a 10V/5W zener would be ok with
500mA -- but keeping the DO-5 case temp under 25ºC requires extraordinary
measures - such as water with ice cubes cooling. In the real world, a
10V/5W zeners are good for c. 160mA provided they have breathing room and
some air movement.
>What that gives you is a more smooth voltage transition
>of regulation, not like the"chopping" effect of solid state.
>You can hear this effect in the audio signal.
>-
* undiluted codswallop
>Solid state has no place here and in my opinion is
>nothing more than someone trying to re-invent the
>wheel by limiting component space and cost. Also,
>gas regulators provide DC filtering. Many people don't
>realize that fact.
* apparently President Bob doesn't realize that zeners do this.
>Maybe that's why this amplifier sounds
>so good on the air. 73 and thanks for your comments.
* ur welcome, Mr. President.
>Bob
>President/CTI ComTec, Inc.
>-
>The URL is www.cticomtec.com
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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