Glad to see you here Rich. I have learned a lot from you in your articles &
your great help on the phone with my 3-500 amps that I couldn't stop a
parasitic in. Your kit you sent me along with a lot of literature cured that
amp & the suppressors don't burn up . Amps runs full out on 160 thru 10
mtrs. Again thanks for your help.
"• R. L. Measures." wrote in message
...
Even though it does not appear on the schematic diagram, every tube-type
HF amplifier has a resonant circuit in its anode circuitry that resonates
somewhere in the VHF region. This called a parasitic resonance. Whenever
the DC anode current changes, the parasitic circuit rings - much like a
struck bell and generates a smallish damped wave signal at the VHF
resonance point. - note - this is the same principle that enabled spark
transmtters to produce RF from a DC source.
Since all tubes have feedback C between the output (anode) and the input
(cathode for cathode-driven and grid for grid driven), the damped-wave VHF
signal is amplified - whereupon some of the amplified signal can be
fedback again and re-amplified -- resulting in oscillation. Because
tube gain is pettty much tube-transconductance x the resistive load (RL)
on the anode, one way to reduce the chance of VHF oscillation is to
artifically reduce the VHF gain of the tube by lowering the VHF-RL
presented to the anode by the parasitic resonance. This is done by
decreasing the VHF-Q of the parasitic resonance circuit. In other words,
to decrease Q, increase R. Traditionally this has been done by winding a
Cu wire coil around a carbon-comp resistor and soldering the coil in
parallel with the resistor. In a typical 2. 3-500Z amplifier this
configuration produces a Q of c. 5 at 100MHz. Misfortunately a Q of 5 is
not quite low enough to reduce VHF gain enough so that oscillation can not
be sustained It apparently takes a Q of 2 at 100MHz to achieve
acceptable VHF stability. One way to decrease Q involves exchanging the
highly-conductive Cu wire for highly-resistive Ni-Cr wire This simple
change results in a Q of c. 2 at 100MHz as measured on a HP 4191A
Z-analyzer. By using two Ni-Cr VHF suppressors per 2-500z, Q can be
further reduced to c. 1.5.
- end

--
Richard L. Measures. 805-386-3734,AG6K, www.somis.org

In article , "Howard K0ACF"
wrote:

Glad to see you here Rich. I have learned a lot from you in your articles &
your great help on the phone with my 3-500 amps that I couldn't stop a
parasitic in. Your kit you sent me along with a lot of literature cured that
amp & the suppressors don't burn up . Amps runs full out on 160 thru 10
mtrs. Again thanks for your help.

• ur welcome Howard. 73

"• R. L. Measures." wrote in message
...
Even though it does not appear on the schematic diagram, every tube-type
HF amplifier has a resonant circuit in its anode circuitry that resonates
somewhere in the VHF region. This called a parasitic resonance. Whenever
the DC anode current changes, the parasitic circuit rings - much like a
struck bell and generates a smallish damped wave signal at the VHF
resonance point. - note - this is the same principle that enabled spark
transmtters to produce RF from a DC source.
Since all tubes have feedback C between the output (anode) and the input
(cathode for cathode-driven and grid for grid driven), the damped-wave VHF
signal is amplified - whereupon some of the amplified signal can be
fedback again and re-amplified -- resulting in oscillation. Because
tube gain is pettty much tube-transconductance x the resistive load (RL)
on the anode, one way to reduce the chance of VHF oscillation is to
artifically reduce the VHF gain of the tube by lowering the VHF-RL
presented to the anode by the parasitic resonance. This is done by
decreasing the VHF-Q of the parasitic resonance circuit. In other words,
to decrease Q, increase R. Traditionally this has been done by winding a
Cu wire coil around a carbon-comp resistor and soldering the coil in
parallel with the resistor. In a typical 2. 3-500Z amplifier this
configuration produces a Q of c. 5 at 100MHz. Misfortunately a Q of 5 is
not quite low enough to reduce VHF gain enough so that oscillation can not
be sustained It apparently takes a Q of 2 at 100MHz to achieve
acceptable VHF stability. One way to decrease Q involves exchanging the
highly-conductive Cu wire for highly-resistive Ni-Cr wire This simple
change results in a Q of c. 2 at 100MHz as measured on a HP 4191A
Z-analyzer. By using two Ni-Cr VHF suppressors per 2-500z, Q can be
further reduced to c. 1.5.
- end

--
Richard L. Measures. 805-386-3734,AG6K, www.somis.org

--
Richard L. Measures. AG6K, 805-386-3734, www.somis.org

95 R. L. Measures. wrote:

The character 95 you seem to be fond of is not part of the character
set you use for your news postings.

In article , Rob
wrote:

95 R. L. Measures. wrote:

The character 95 you seem to be fond of is not part of the character
set you use for your news postings.

** I did not send 95. I use a UNIX-based operating system. If you
were using a UNIX based OS you would see what I actually write Rob. cheers

--
Richard L. Measures. AG6K, 805-386-3734, www.somis.org

95 R. L. Measures. wrote:
In article , Rob
wrote:

95 R. L. Measures. wrote:

The character 95 you seem to be fond of is not part of the character
set you use for your news postings.

** I did not send 95. I use a UNIX-based operating system. If you
were using a UNIX based OS you would see what I actually write Rob. cheers

I am using Linux. But I guess that does not count as a UNIX based OS.

Check what is in your fullname config setting. There is a character
with hex value 95 there. But you don't have the matching character set
header that is supposed to tell what that character should mean.

(without a character set header, the default character set is 7-bit ASCII
which does not include 95)

In article , Rob
wrote:

95 R. L. Measures. wrote:
In article , Rob
wrote:

95 R. L. Measures. wrote:

The character 95 you seem to be fond of is not part of the character
set you use for your news postings.

** I did not send 95. I use a UNIX-based operating system. If you
were using a UNIX based OS you would see what I actually write Rob. cheers

I am using Linux. But I guess that does not count as a UNIX based OS.

** I don't know Rob. I am using Apple's 10.4 OS.

Check what is in your fullname config setting.

** I am not using an OS with such a setting in the system prefs.

There is a character
with hex value 95 there. But you don't have the matching character set
header that is supposed to tell what that character should mean.

(without a character set header, the default character set is 7-bit ASCII
which does not include 95)

--
Richard L. Measures. AG6K, 805-386-3734, www.somis.org

95 R. L. Measures. wrote:
In article , Rob
wrote:

95 R. L. Measures. wrote:
In article , Rob
wrote:

95 R. L. Measures. wrote:

The character 95 you seem to be fond of is not part of the character
set you use for your news postings.

** I did not send 95. I use a UNIX-based operating system. If you
were using a UNIX based OS you would see what I actually write Rob. cheers

I am using Linux. But I guess that does not count as a UNIX based OS.

** I don't know Rob. I am using Apple's 10.4 OS.

It doesn't matter anyway.
The OS has nothing to do with this.
Your news program is broken, or does not expect the use you make of it.

As your news program does not tell what character set you use, you should
limit your characters to the 00-7F range.

Check what is in your fullname config setting.

** I am not using an OS with such a setting in the system prefs.

Probably it is in your news program.
Somewhere you have set that your name, "95 R. L. Measures.", has to
appear above your news postings.
When you change that to "R. L. Measures" all trouble is gone.

And don't insert that character in replies either.

There is a character
with hex value 95 there. But you don't have the matching character set
header that is supposed to tell what that character should mean.

(without a character set header, the default character set is 7-bit ASCII
which does not include 95)

In article ,
(• R. L. Measures.) wrote:

If you
were using a UNIX based OS you would see what I actually write

Richard-

Is it the OS, or is it the font?

I see a • character that may be different from what you see. What font
are you using?

Fred
K4DII

Fred McKenzie wrote:
In article ,
(95 R. L. Measures.) wrote:

If you
were using a UNIX based OS you would see what I actually write

Richard-

Is it the OS, or is it the font?

I see a 95 character that may be different from what you see. What font
are you using?

His postings do not specify the character set he is using.
Probably it is Windows-1252. A more standard character set leaves the
character 95 undefined.

On 03 Jul 2010 18:32:59 GMT, Rob wrote:

Fred McKenzie wrote:
In article ,
(95 R. L. Measures.) wrote:

If you
were using a UNIX based OS you would see what I actually write

Richard-

Is it the OS, or is it the font?

I see a 95 character that may be different from what you see. What font
are you using?

His postings do not specify the character set he is using.
Probably it is Windows-1252.

Most likely, if that code was supposed to represent a bullet.

A more standard character set leaves the
character 95 undefined.

Codes 80..9F hex and U+0080 .. U+009F belong to the C1 control area in
many standards (ISO 8859 and Unicode) and 95h represents "Message
Waiting" control code.

While I have used C1 controls to control terminals, I do not recall
that I would have used MW :-).