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In the VHF/UHF Handbook, chapter Receivers, Transmitters And Transceivers ,
section, 'Tuned Circuits'; the author writes: "If discs are used, the
capacitance varies in a very non-linear manner with the distance between them.
It is: C(pF) = 0.00885 x Area (sq mm) / Spacing (mm)"
The equation for capacitance vs area vs spacing is linear. What's up?
John, N9RF
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Hey Jim,
No, the book is ARRL's VHF/UHF Handbook. The formula is correct, as it is
found elsewhere, including Orr's book (p 2-6, 23rd Edition). He includes the term
for inclusion of a dielectric.
He states (correctly, as the equation illustrates), that C is proportional to
the area of the plates and inversely proportional to the spacing between
them. Halve the spacing -- double the C.
My problem is the statement of Dick Bidulph, M0CGN, author of the ARRL
publication regarding the "nonlinear manner". Unless, of course, he is using a
nonlinear screw!
-J
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--- In ham_amplifiers@..., jmltinc@... wrote:
In the VHF/UHF Handbook, chapter Receivers, Transmitters And
Transceivers , section, 'Tuned Circuits'; the author writes: "If discs are used, the capacitance varies in a very non-linear manner with the distance between them. It is: C(pF) = 0.00885 x Area (sq mm) / Spacing (mm)"
The equation for capacitance vs area vs spacing is linear. What's up?
John, N9RF ### You double the spacing between any two plates... and C drops to just 1/4 of the original. [ V rating doubles]. ### conversely... u reduce the spacing by 1/2 the original... and C increases 4 x [V rating drops in 1/2] later... Jim
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--- In ham_amplifiers@..., "pentalab" <jim.thomson@...> wrote:
--- In ham_amplifiers@..., jmltinc@ wrote:
In the VHF/UHF Handbook, chapter Receivers, Transmitters And
Transceivers ,
section, 'Tuned Circuits'; the author writes: "If discs are
used, the
capacitance varies in a very non-linear manner with the distance between them.
It is: C(pF) = 0.00885 x Area (sq mm) / Spacing (mm)"
The equation for capacitance vs area vs spacing is linear. What's up?
John, N9RF
########### Congrat's... u just found ur 1st mistake. If this is orr's latest blue book..... which page is it on ??? I found 38 mistakes in it so far.. mainly typo's.... have not got to the vhf/uhf stuff yet. Jim
### You double the spacing between any two plates... and C
drops to just 1/4 of the original. [ V rating doubles].
### conversely... u reduce the spacing by 1/2 the original... and C increases 4 x [V rating drops in 1/2]
later... Jim
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On Nov 3, 2006, at 2:17 PM, jmltinc@... wrote: In the VHF/UHF Handbook, chapter Receivers, Transmitters And Transceivers ,
section, 'Tuned Circuits'; the author writes: "If discs are used, the
capacitance varies in a very non-linear manner with the distance between them.
It is: C(pF) = 0.00885 x Area (sq mm) / Spacing (mm)"
The equation for capacitance vs area vs spacing is linear. What's up? More taurine feces, John, Cheerz
John, N9RF
Yahoo! Groups Links
R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org
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On Nov 3, 2006, at 4:53 PM, jmltinc@... wrote: Hey Jim,
No, the book is ARRL's VHF/UHF Handbook. The formula is correct, as it is
found elsewhere, including Orr's book (p 2-6, 23rd Edition). He includes the term
for inclusion of a dielectric.
He states (correctly, as the equation illustrates), that C is proportional to
the area of the plates and inversely proportional to the spacing between
them. Halve the spacing -- double the C.
My problem is the statement of Dick Bidulph, M0CGN, author of the ARRL
publication regarding the "nonlinear manner". Unless, of course, he is using a
nonlinear screw! Guffaw!! R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org
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On Nov 3, 2006, at 3:36 PM, pentalab wrote: --- In ham_amplifiers@..., jmltinc@... wrote:
In the VHF/UHF Handbook, chapter Receivers, Transmitters And
Transceivers ,
section, 'Tuned Circuits'; the author writes: "If discs are used, the
capacitance varies in a very non-linear manner with the distance between them.
It is: C(pF) = 0.00885 x Area (sq mm) / Spacing (mm)"
The equation for capacitance vs area vs spacing is linear. What's up?
John, N9RF ### You double the spacing between any two plates... and C drops
to just 1/4 of the original. [ V rating doubles].
### conversely... u reduce the spacing by 1/2 the original... and C
increases 4 x [V rating drops in 1/2] Correctomundo, Jim. Congrats
later... Jim
Yahoo! Groups Links
R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org
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So, is the equation wrong? Jim's answer implies an inverse square equation.
-J
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ORIGINAL MESSAGE: On Sat, 04 Nov 2006 00:27:50 -0000, "pentalab" <jim.thomson@...> wrote: I found 38 mistakes in it so far.. mainly typo's.... ------------ REPLY FOLLOWS ------------ The plural of typo is typos. Sorry, couldn't resist. :-) Bill, W6WRT
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no square in the equation... C = k * ( area/distance) k is the factor for insulator dielectric factor () is the ratio of the plate area divided by the distance between plates denny --- In ham_amplifiers@..., jmltinc@... wrote:
So, is the equation wrong? Jim's answer implies an inverse square
equation.
-J
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On Nov 6, 2006, at 3:02 PM, ad4hk2004 wrote: no square in the equation...
C = k * ( area/distance) As I recall, this is not the equation.
k is the factor for insulator dielectric factor
() is the ratio of the plate area divided by the distance between plates
denny
--- In ham_amplifiers@..., jmltinc@... wrote:
So, is the equation wrong? Jim's answer implies an inverse square
equation.
-J
Yahoo! Groups Links
R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org
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