开云体育

Those tests where at full power, with quite a bit ALC pulled,
also quite a bit of processing.
One can say that both radios was "forced" a bit, did also use
an audio RF clipper with the KWM2.

This is a modulated spectrum, I modulated the radios with the
mic for about 45 secs and this is the total sample.

I tested the FT-1000D also at 100W but difference was very
small, only changed a db or two towards the better.

Yes "on the air" I have tested to run the FT-1000D with no ALC
compared to ALC on top of the "blue" range. Difference 5 kHz away
is always about 5 dB lower spectrum with no ALC so yes I know that
it makes quite a bit difference.

Yes agree on the calibration also Jim, my two 1000Ds also needed
quite a bit of adjustments. I never did try to increase bias on these
radios, I remember I was playing with that when I had a TS-930.
Since I have measuring equipment I will play a little with that when
I get some time.

73 Jim SM2EKM
----------------------

pentalab wrote:

This is a very good point by Greg, I agree 100%

73 Jim SM2EKM
---------------------
badgerscreek wrote:

Mark wrote:

I just ran across this on yahoo groups

<>

73
Mark
W0NCL

__________________________________________________________
Get your email and see which of your friends are online - Right on the New Yahoo.com
( <>)

And apparently you must have a call sign to join too.

zerobeat40 wrote:

--- In ham_amplifiers@... <mailto:ham_amplifiers%40yahoogroups.com>, R L Measures <r@...> wrote:

Do you have a FCC callsign?

No, sir. Is that a requirement for inclusion in this group?

Definitely Not. So why do you hide your name?

I don't hide my name. My given name is Z Sampson Thompson, per my
birth cert. No ham ticket, no callsign. Not a famous author, nobody
knows me anyway. Why does it matter. I've gone by "Z" or "Zed" all
my life.

Career was spent in comunications and related...HF/SW broadcasting,
ship-to-shore, etc. Climbed lots of towers, designed lots of
transmitters, had hams around me the whole time of course and even
have been heard on HF SSB from one or another ham's station, but never
got around to getting the ham ticket.

Any other personal questions on your mind?

Z

Welcome to the group Z.

I just ran across this on yahoo groups




73
Mark
W0NCL



____________________________________________________________________________________
Get your email and see which of your friends are online - Right on the New Yahoo.com
()

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

It can't be Rauch because he knows that the grid has to be positive
with respect to the cathode in order for grid-current to flow.

Sounds like someone needs to review his basic tube theory.
Specifically, look up "contact potential bias".

Now, for the experiment.

Lay tube on bench. Any tube, as long as it works. Apply specified
filament/heater current. Place a high-Z voltmeter between the
cathode/fil and the control grid. Once the cathode warms up, what do
you read? Is the grid negative W.R.T. to cathode, or positive? Given
that the voltmeter has finite resistance, would you say that the grid
current is zero, or non-zero?

Connect a 100kohm resistor between grid and cathode. Measure the
potential difference between grid and cathode. Given that this
voltage is non-zero, is there grid current? What is the polarity of
the voltage?

The experiment is more dramatic with a transmitting tube. I don't
recall what the values will be for a 3-500Z, but I just ran through
some 4CX250Bs...typ voltage developed in the experiment is control
grid negative to cathode by 15-30 volts, with grid current flowing.

Let us know the results.

Z

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

Do you have a FCC callsign?

No, sir. Is that a requirement for inclusion in this group?

Definitely Not. So why do you hide your name?

I don't hide my name. My given name is Z Sampson Thompson, per my
birth cert. No ham ticket, no callsign. Not a famous author, nobody
knows me anyway. Why does it matter. I've gone by "Z" or "Zed" all
my life.

Career was spent in comunications and related...HF/SW broadcasting,
ship-to-shore, etc. Climbed lots of towers, designed lots of
transmitters, had hams around me the whole time of course and even
have been heard on HF SSB from one or another ham's station, but never
got around to getting the ham ticket.

Any other personal questions on your mind?

Z

On Nov 1, 2006, at 12:47 PM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

RICH SEZ... Do you have a FCC callsign?

### He doesn't need one..... I don't have a FCC callsign either.

chortle

Check the master list.... a LOT of fellows with no callsigns... who
cares.

Charles Thomas Rauch, Jr.

### some ZL remarked that having to take a CW exam was akin to
having to "shoe a horse" for a driver's exam. He's right of
course.

### Unless of course this is a conspiracy theory... and perhaps "Z"
is actually Rauch !! .... or maybe even Denny Haad.

It can't be Rauch because he knows that the grid has to be positive with respect to the cathode in order for grid-current to flow.

later... Jim VE7RF





Yahoo! Groups Links

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

On Nov 1, 2006, at 3:38 PM, zerobeat40 wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Nov 1, 2006, at 12:20 PM, zerobeat40 wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

zerobeat40 <zerobeat40@> wrote:
Hey, I tried to put the NFB into a solid state amp once, being
used as
a driver for commercial HF SSB. It was not so easy....

Z

Do you have a FCC callsign?

No, sir. Is that a requirement for inclusion in this group?

Definitely Not. So why do you hide your name?

I came
here to avoid the censorship of another group that looked down upon
those of us who were not licensed.

He also looks down on those who do not agree with his technical missteps.

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

--- In ham_amplifiers@..., "pentalab" <jim.thomson@...> wrote:

If u scroll through the messages... u will see that # 863 has been
blown out ! I responded to it last night... then it comes back
as "message 863 can't be retrieved" Did the fellow blow it out
himself... or was it censored... or what ?

Yahoogroups allows the originator of a posting to delete it. Or the
moderator can. I don't fundamentally like that - once posted, a
posting ought stay as a matter of record.

The 2 tone test is flawed, and isn't used anymore in the
commercial world. By juggling the spacing of the 2 x tones, you
can hit a .."sweet spot" and come up with really good IMD numbers.

That's usually with very wide spacing. At very narrow spacing, you
challenge the power supply bypassing, so the worst numbers often occur
at that test condition.

They all use the noise test these days... pump the xcvr with
bandwidth limited white noise.... that will drive the xcvr to full
pep output.... and simulate voice or many data tones. In the
commercial world, it's common to use 4 x multiplexed ssb
channels... or as many as 16 x mark/space combo's... sometimes
interleaved.

Noise Power Ratio puts band-limited white noise through the rig, with
a notch in the middle of it. IMD products will tend to fill in the
notch. Very harsh test.

You will read the arguments of referencing IMD to one tone of
a 2 x tone sig instead of PEP. For several multiplexed ssb
channels or many data tones... this is valid. For a single
voice channel on ssb, like we use.... it's not needed.

The ARRL USED to ref IMD to one tone.... now they ref to
PEP. S-meter's on xcvr's are all PEAK reading devices. We all
hear.... "your signal is 10 over S-9.... but ur splatter is S-
6.... 4 khz away" The ref here is IMD to PEP. We don't
hear...." gee, I gotta ref off freq splatter to on freq signal
strength MINUS 6db".

Here's a quote from "SSB systems and circuits"

"ANOTHER deficiency of the 2 x tone test is that the "3rd order"
products observed on a spectrum analyzer are actually the sum of
the 3rd and ALL higher ODD order components. Typ, the 5th order
component is OUT of phase with the 3rd, which tends to PRODUCE
distortion CANCELLATION. This leaves the FALSE impression that the
IMD is better than it really is."

Sad. It's in error. The 5th order component is at a different
frequency than the 3rd order component, therefore they are completely
distinguishable from each other.

Ex: 5MHz and 5.001MHz are the incident sigs. The 3rd ord will be
4.999 and 5.002 MHz. 5th order will be 4.998 and 5.003 MHz. They
don't sit on each other, and don't add to each other in any way.

They go on to say a better method for single channel ssb voice
is to look at plane voice on a digital storage spectrum
analyzer... over a long time period... whereby all the out of
band IMD products are held in a "peak hold" mode.... the
concept being to look at long term spectral power densisty.

A 2 x tone test imo... is pretty lame duck... it won't dynamically
exercise HV and bias + fil supplies either.... since the 2 x
tone puts everything in a .."static state".

Yes, quite. The difficult is in coming up with a repeatable test.
It's not scientific unless it's repeatable - two guys in two different
locations, using two sets of test gear should come up with the same
results. The BW-limited noise test is a good one in this regard.

I tried the white noise test... and it def produces more IMD than
plane voice ever will.... since the white noise looks like
thousands of tones... all beating against each other.

BTW... when running white noise into the xcvr.... the plate current
on the linear is EXACTLY 1/2 the key down value.... so u can
use white noise to tweak the tune/load caps to max pep output.

You're driving it too hard. Peak to average ratio of BW-limited white
noise (the voltage distribution of BW-limited white noise is closer to
a Rayleigh distribution) is approx 16:1. The word "approx" is
important beause in truth, there is some percentage probability of ANY
power level being present at some time. 16:1 is the diff between 50%
probabiliy and 1%. Adequate for communications-grade amps.

Even EESB comes out looking better than a white noise test... OR
using W8JI's convoluted 2 x tone test, where he uses 2 x
extremly wide spaced tones.... like 100 hz and 3100 hz.... then
sez the total IMD BW is 9 khz wide.

In U.S. dialects, a vocalized sibiliant contains both low and high.
E.G. "Z" or "J". However, the wide-spaced test is actually one of
those that does not stress the power supply much, therefore you tend
to get artificially good values.

Try as hard as you want... you can't find ANY combo of words or
phrases that will produce SIMULTANEOUS highs and lows.

Sure can...any vocalized sibilant. To be exact, "Z" is a "voiced
alveolar sibilant" and is often used as a "torture test" for system BW
commercially when test gear is unavailable.

Has anybody tried adjusting the Zsac on these big tubes from one
extreme to the other.. and actually measured the imd ?? Kinda a
moot point... unless the xcvr is the same or better IMD wise,
nobody would ever hear any benefit.

The tendency is for IMD to vary in only a small amount. You can
improve it at low levels by sending the ZSAC very high, but that does
not change IMD at high levels. When you get ZSAC to a too-low level,
IMD shoots up quite a bit. That's why even in commercial gear,
fixed-voltage bias is common, it just doesn't matter much as long as
you've got some ZSAC.

Later... Jim VE7RF

Z

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Nov 1, 2006, at 12:20 PM, zerobeat40 wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

zerobeat40 <zerobeat40@> wrote:
Hey, I tried to put the NFB into a solid state amp once, being
used as
a driver for commercial HF SSB. It was not so easy.

Assuming a pair of NPN transistors delivering 100 watts at 30MHz,
running from 13.8VDC, producting -30dBc IMD that we want to
improve by
about 10dB. The correct value resistor is approx 0.2 ohms and it
must
dissipate 15 watts, if the amp is to survive clumsy tuning into an
antenna tuner at full power. You could get away with a 5 watt device
if you insisted on only SSB (no CW or FM) and only into a matched
load. Smallest resistor I was able to find to meet this was a chip
style component, about 1/2 inch X 1/2 inch. It measured 5nH of
inductance. At 30MHz, XL=nearly one ohm. The stage gain at 30MHz was
reduced to approx 2dB, and the phase shift of this inductance
reduced
the IMD benefits of the NFB to having no IMD reduction at all. At
1MHz, the solution worked very nicely - stage gain stabilized at
14dB,
and IMD measured about -42dBc (referenced to either of two incident
carriers)

If you could somehow create a 15 watt resistor that is 0.2 ohms and
under approx 0.2nH of inductance, then your proposed solution will
work.

!. I would use 50v transistors.

For 50V transistors operating at 100W per pair, the required resistor
is 0.8 ohms, wherein you'd need 0.8nH of inductance or less, still at
15 watts. Can you find that one? For MRF150s, it's 0.5 ohms, needing
less than 0.5nH of inductance, this time at 25 watts.

Let us know.

Z

Do you have a FCC callsign?

No, sir. Is that a requirement for inclusion in this group? I came
here to avoid the censorship of another group that looked down upon
those of us who were not licensed. If, however, this group is
similarly exclusionary, then please accept my apologies, and I shall
depart with what little grace I may have left.


Z

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

RICH SEZ... Do you have a FCC callsign?

### He doesn't need one..... I don't have a FCC callsign either.
Check the master list.... a LOT of fellows with no callsigns... who
cares.

### some ZL remarked that having to take a CW exam was akin to
having to "shoe a horse" for a driver's exam. He's right of
course.

### Unless of course this is a conspiracy theory... and perhaps "Z"
is actually Rauch !! .... or maybe even Denny Haad.

later... Jim VE7RF

If u scroll through the messages... u will see that # 863 has been
blown out ! I responded to it last night... then it comes back
as "message 863 can't be retrieved" Did the fellow blow it out
himself... or was it censored... or what ?

The fellow was commenting on the fact that 3rd order IMD products
don't tell the entire story. Most of the xcvr's will show
pretty good 3rd order specs... then the 5-7-9-11th distortion
products flatline.... and don't improve very much.... and it's the
higher order products that create all the off freq QRM.

The 2 tone test is flawed, and isn't used anymore in the
commercial world. By juggling the spacing of the 2 x tones, you
can hit a .."sweet spot" and come up with really good IMD numbers.

They all use the noise test these days... pump the xcvr with
bandwidth limited white noise.... that will drive the xcvr to full
pep output.... and simulate voice or many data tones. In the
commercial world, it's common to use 4 x multiplexed ssb
channels... or as many as 16 x mark/space combo's... sometimes
interleaved.

You will read the arguments of referencing IMD to one tone of
a 2 x tone sig instead of PEP. For several multiplexed ssb
channels or many data tones... this is valid. For a single
voice channel on ssb, like we use.... it's not needed.

The ARRL USED to ref IMD to one tone.... now they ref to
PEP. S-meter's on xcvr's are all PEAK reading devices. We all
hear.... "your signal is 10 over S-9.... but ur splatter is S-
6.... 4 khz away" The ref here is IMD to PEP. We don't
hear...." gee, I gotta ref off freq splatter to on freq signal
strength MINUS 6db".

Here's a quote from "SSB systems and circuits"

"ANOTHER deficiency of the 2 x tone test is that the "3rd order"
products observed on a spectrum analyzer are actually the sum of
the 3rd and ALL higher ODD order components. Typ, the 5th order
component is OUT of phase with the 3rd, which tends to PRODUCE
distortion CANCELLATION. This leaves the FALSE impression that the
IMD is better than it really is."

They go on to say a better method for single channel ssb voice
is to look at plane voice on a digital storage spectrum
analyzer... over a long time period... whereby all the out of
band IMD products are held in a "peak hold" mode.... the
concept being to look at long term spectral power densisty.

A 2 x tone test imo... is pretty lame duck... it won't dynamically
exercise HV and bias + fil supplies either.... since the 2 x
tone puts everything in a .."static state".

I tried the white noise test... and it def produces more IMD than
plane voice ever will.... since the white noise looks like
thousands of tones... all beating against each other.

BTW... when running white noise into the xcvr.... the plate current
on the linear is EXACTLY 1/2 the key down value.... so u can
use white noise to tweak the tune/load caps to max pep output.

Even EESB comes out looking better than a white noise test... OR
using W8JI's convoluted 2 x tone test, where he uses 2 x
extremly wide spaced tones.... like 100 hz and 3100 hz.... then
sez the total IMD BW is 9 khz wide.

Try as hard as you want... you can't find ANY combo of words or
phrases that will produce SIMULTANEOUS highs and lows.

Has anybody tried adjusting the Zsac on these big tubes from one
extreme to the other.. and actually measured the imd ?? Kinda a
moot point... unless the xcvr is the same or better IMD wise,
nobody would ever hear any benefit.

Later... Jim VE7RF

On Nov 1, 2006, at 12:20 PM, zerobeat40 wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

zerobeat40 <zerobeat40@...> wrote:
Hey, I tried to put the NFB into a solid state amp once, being used as
a driver for commercial HF SSB. It was not so easy.

Assuming a pair of NPN transistors delivering 100 watts at 30MHz,
running from 13.8VDC, producting -30dBc IMD that we want to improve by
about 10dB. The correct value resistor is approx 0.2 ohms and it must
dissipate 15 watts, if the amp is to survive clumsy tuning into an
antenna tuner at full power. You could get away with a 5 watt device
if you insisted on only SSB (no CW or FM) and only into a matched
load. Smallest resistor I was able to find to meet this was a chip
style component, about 1/2 inch X 1/2 inch. It measured 5nH of
inductance. At 30MHz, XL=nearly one ohm. The stage gain at 30MHz was
reduced to approx 2dB, and the phase shift of this inductance reduced
the IMD benefits of the NFB to having no IMD reduction at all. At
1MHz, the solution worked very nicely - stage gain stabilized at 14dB,
and IMD measured about -42dBc (referenced to either of two incident
carriers)

If you could somehow create a 15 watt resistor that is 0.2 ohms and
under approx 0.2nH of inductance, then your proposed solution will
work.

!. I would use 50v transistors.

For 50V transistors operating at 100W per pair, the required resistor
is 0.8 ohms, wherein you'd need 0.8nH of inductance or less, still at
15 watts. Can you find that one? For MRF150s, it's 0.5 ohms, needing
less than 0.5nH of inductance, this time at 25 watts.

Let us know.

Z

Do you have a FCC callsign?

Yahoo! Groups Links

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

zerobeat40 <zerobeat40@...> wrote:
Hey, I tried to put the NFB into a solid state amp once, being used as
a driver for commercial HF SSB. It was not so easy.

Assuming a pair of NPN transistors delivering 100 watts at 30MHz,
running from 13.8VDC, producting -30dBc IMD that we want to improve by
about 10dB. The correct value resistor is approx 0.2 ohms and it must
dissipate 15 watts, if the amp is to survive clumsy tuning into an
antenna tuner at full power. You could get away with a 5 watt device
if you insisted on only SSB (no CW or FM) and only into a matched
load. Smallest resistor I was able to find to meet this was a chip
style component, about 1/2 inch X 1/2 inch. It measured 5nH of
inductance. At 30MHz, XL=nearly one ohm. The stage gain at 30MHz was
reduced to approx 2dB, and the phase shift of this inductance reduced
the IMD benefits of the NFB to having no IMD reduction at all. At
1MHz, the solution worked very nicely - stage gain stabilized at 14dB,
and IMD measured about -42dBc (referenced to either of two incident
carriers)

If you could somehow create a 15 watt resistor that is 0.2 ohms and
under approx 0.2nH of inductance, then your proposed solution will
work.

!. I would use 50v transistors.

For 50V transistors operating at 100W per pair, the required resistor
is 0.8 ohms, wherein you'd need 0.8nH of inductance or less, still at
15 watts. Can you find that one? For MRF150s, it's 0.5 ohms, needing
less than 0.5nH of inductance, this time at 25 watts.

Let us know.

Z

On Nov 1, 2006, at 10:56 AM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Oct 31, 2006, at 12:18 PM, FRANCIS CARCIA wrote:

I suspect you would be better off with a 300 watt amplifier

running

closer to class A with transformer feed back, Most RF

transistors

RICH SEZ... I would use 50v transistors.

### Kinda tough in a mobile application...

3, YC--156s mobile. Roger that good buddy.

or some emergency
application where u use 12 vdc batteries, etc. These 50 vdc
finals don't seem to be much better than 30 vdc finals. I
believe there are some 70-100 v devices out there too.

I drive a car that uses a 208v battery.

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Oct 31, 2006, at 12:18 PM, FRANCIS CARCIA wrote:

I suspect you would be better off with a 300 watt amplifier

running

closer to class A with transformer feed back, Most RF

transistors

RICH SEZ... I would use 50v transistors.

### Kinda tough in a mobile application... or some emergency
application where u use 12 vdc batteries, etc. These 50 vdc
finals don't seem to be much better than 30 vdc finals. I
believe there are some 70-100 v devices out there too.

### On another note.... some where I saw the specs for the common
transistor PA all these 11m ops use.. The manufacturer depicted a
graph of IMD vs power out in pep. Interesting, cuz the lower the
power out... the IMD just kept getting better.

### I still believe these 200 w xcvr's are the way to go... then
u can get a clean 50-150w out of them. Crank the idle current up
a bit... and watch the imd drop some more.

### There's no point in trying to achieve Class A specs like the
MK-V's I have.....at that point the xcvr is now better than the
linear amp behind it. The total systen IMD is gonna be the lesser
of the two. ..... unless u run the linear in class A.... which is
going to require a huge amount of anode dissipation. A sliding
bias scheme would be the ideal ticket... to minimize anode diss
during Class A. Krell does this with their Class A audio amps...
works too.

Later... Jim VE7RF

Let us know when you find that resistor.

Z

--- In ham_amplifiers@..., R L Measures <r@...>

wrote:

tnx, Tony. Since adding RF-NFB to a transistor amplifier is as
simple as adding unbypassed R to the emitter leads, it puzzles

me

why

Ham transceiver manufacturers don't wake up and start building
pristine radios.

Since the TS-830S uses essentially a copy of the KWM-2's RF
amplifier, it isn't surprising that the 830 has a reputation

for

cleanliness.

cheerz

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

On Oct 31, 2006, at 3:17 PM, pentalab wrote:

--- In ham_amplifiers@..., "pentalab" <jim.thomson@...>
wrote:

RICH SEZ.... 3A diodes will do 200a-pk. Not many HV transformers

will. The original Plywood Box amplifier used 150a-pk, 2.5A avg
diodes in a FWB > and the diodes survived at least 4 flashovers

to gnd without benefit of a HV fuse.

### All as you are doing is stressing the hell outa the diodes.
The 5th time you might not have been lucky. For a 14 kw amp,

like ur plywood box.... you shoulda been using 1 kv-6A diodes
[400A surge] like a 6A10.... the 0nly diode worth buying these
days.

### Rich, with that 40 A undersized breaker you have installed
in the 240 V line... it would be on the ragged edge on ssb to
start with... in a pre-heated condx.... a flashover would tip it
over the edge. IF you installed a 100-125A breaker, you could
have smoked the diodes. As is, with 14 kw out... ur line

current from the 240 V line would be 110 A on keydown... close to
55A on ssb.


########### Lemme re-phrase that..... "with a 253 lb dahl and a
100-125 A breaker, and no HV fuse... you have a good chance of
stressing the diodes... esp the smaller variety..... use a 440 lb
dahl and a 150 A breaker.. and NO hv fuse, imo ur plane nuts "#####

It worked okay on SSB.

Later... Jim VE7RF

Later... Jim VE7RF

...
R L Measures, AG6K, 805.386.3734
r@..., , rlm@, www.somis.org

Yahoo! Groups Links

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

On Oct 31, 2006, at 3:05 PM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Oct 30, 2006, at 1:21 PM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...>

wrote:...

RICH SEZ....Probably 90% of 'em will tell us that heavy straps

have zero L.

### WIDE straps do have zero L.

Not a sound wager, The 100Ω MOF resistors we use in our suppressor
retrofit kits are 20mm long and they have c. 11nH of inductance.

I measure ZERO L on a 3'
length of 3/4" wide Cu strap on my B+K 875-B. It reads down
to .1uh Even if it was .049uh or less... it would still read
00.0 uh. Let's say it was .049uh for 3' [36"]..... then a 3.6"
length of 3/4" wide strap is gonna be just .0049 uh. ... which
is zip imo. 1" wide strap will be even less uh.

You would do well to read Fred Terman's chapter on inductance.

end

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

On Oct 31, 2006, at 2:00 PM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Oct 30, 2006, at 1:43 PM, pentalab wrote:

it off... all was well. If that had been the INPUT

insulator,,, I

could have easily smoked the 3 A diodes,

RICH SEZ.... 3A diodes will do 200a-pk. Not many HV transformers

will. The original Plywood Box amplifier used 150a-pk, 2.5A avg
diodes in a FWB > and the diodes survived at least 4 flashovers to
gnd without benefit of a HV fuse.

### All as you are doing is stressing the hell outa the diodes.

So why didn't they fail?

The 5th time you might not have been lucky. For a 14 kw amp, like
ur plywood box.... you shoulda been using 1 kv-6A diodes [400A
surge] like a 6A10.... the 0nly diode worth buying these days.

### Rich, with that 40 A undersized breaker you have installed
in the 240 V line... it would be on the ragged edge on ssb to
start with... in a pre-heated condx.... a flashover would tip it
over the edge. IF you installed a 100-125A breaker, you could
have smoked the diodes. As is, with 14 kw out... ur line current
from the 240 V line would be 110 A on keydown... close to 55A on
ssb.

Why design one to run A0 when A0 is illegal and it triples the cost and weight of the PS?

Later... Jim VE7RF

...
R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

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R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org