开云体育

To achieve 1,5% ripple from a 6-pulse power supply of 5KV at 3A you will
need a capacitor of 0,32?F.
Without any cap ripple will be 4%.
You will not here any hum from a transmitter without capacitor in the
6-pulse capacitor when using sideband transmissions.
From a carrier you here little hum on zerobeat.

The formula to find C for the 3-phase bridge circuit is the same as for any
other circuit, just calculate C from XC by using 300Hz in the formula.
How the transformer is connected does not matter, usually the primary will
be delta for best efficiency and the secondary will be star connected.
You will have 2 diodes per leg. The voltage across one winding is dc/sqrt6.

I my 7KV 4A CCS P/S I use UGE1112AY4 diodes by IXCYS, 3 per leg, just scewed
one into the next.



The transformer secondary is 5KV +/-5%, +/-10% phase to phase, or 2887V
across one winding.
I use 2?F 10KV for smoothing and a crowbar overload circuit with it.

73
Peter


________________________________

From: ham_amplifiers@... [mailto:ham_amplifiers@...]
On Behalf Of pentalab

Then, if we talk 3-phase supply and 6-puls rectifying,
lets say around 5 kV DC potential, how much glitch C
is needed to achieve 1.5 percent ripple?

### Dunno. You would only have 5% ripple with NO cap.... and
with a resonant choke set up.....you probably wouldn't need any
C at all ! [3 phase]

### IF no resonant choke setup... and just a straight C input
filter.... I'm guessing around 5-16 uf would be plenty. It
would also highly depend on the load.

### I haven't found any formulae for a C input filter HV
supply........ with 3 phase. I don't have access to 3 phase....
so never pursued it. It would be the ultimate setup. IF you
find anything... let me know... as I'm most interested. Somebody
is going to ask me to engineer one for em... so I had better
research it.

### I did see some info on C input 3 phase HV supplies some
where.... it's in Orr's older books.... but not alot of info.
Seems to me he had the 3 x primary's connected in a "Delta".....
and the 3 x secondary's tied in a.. "star". The rectifier set
up... if I remember, sorta looked like just 2 x diodes per sec
winding... one flipped around If I remember. The RMS voltage
per sec winding vs no load HVDC output is what threw me.
With say a 1 kv sec.... I'm positive... the OCV hv wasn't 1414
Vdc. [I may well be wrong with this.. just going by memory]

I wonder if 'Z' is the c.s. administrator of the old amps group on
contesting.com? Har, he really shot himself in the foot. He's now
the administrator of a defunct group. He might as well retire, he
won't have anyone to administrate to now but himself!

Hey 'Z' is your name Tom?

Jer

### DREAM ON. I checked 'amps' on contesting .com 3

times

now.... with a microscope [pulling up their archives]..... it

ONLY

got posted TWICE..... once from Mike... once from Alek

later........Jim VE7RF

Yes, that is the distinct number of people who claimed to have
attempted to post it and claimed that it was not posted.

Thank you for the corroborration.

Z

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

To see how much ripple was noticeable on the air, a friend put a
4-1000A on the air with a 6kV FWB PS running a 2uF C-filter. I

could

not hear any ripple -- at least on
SSB. AM would likely have been different.

### The ripple with say 2 uf and 6 kv @ 800 ma should have
been VERY noticeable........ unless of course your xcvr chops off
all the audio below 300 hz. You can hear 120 hz ripple plane
as day on ESSB.

## 6 kv and a 2 uf C input filter would result in real bad
dynamic HV regulation !

### I used 16 uf [with a 2 holer 4-1000] which resulted in 3%
ripple.. I then increased it to 48 uf.. and 1% ripple could be
obtained.

### BTW... my co-hort's tell me that most of these Microwave
oven's all have one 1-uf 5KV oil cap in em. I know one
fellow who paralled about 3 x doz of em... it worked.

Later... Jim VE7RF

--- In ham_amplifiers@..., Jan Erik Holm <sm2ekm@...>
wrote:

Then, if we talk 3-phase supply and 6-puls rectifying,
lets say around 5 kV DC potential, how much glitch C
is needed to achieve 1.5 percent ripple?

Forgot how to calculate it, must dig out books
to do it.

73 Jim SM2EKM

### Dunno. You would only have 5% ripple with NO cap.... and
with a resonant choke set up.....you probably wouldn't need any
C at all ! [3 phase]

### Seems to me.... WAY back on 'amps'.... somebody tried this....
and with NO HV cap installed on the output..... one leg of the
diode board would always blow out ! It needed just a little bit
of C to make things happy for some reason.[3 phase + resonant
choke.... NO output HV cap. ]

### IF no resonant choke setup... and just a straight C input
filter.... I'm guessing around 5-16 uf would be plenty. It
would also highly depend on the load.

### With NO load [just the eq resistor's across the lytics, etc...
which basicly is zip]... ripple is nil. The greater the
load.... the worse any ripple gets. You can see 3% ripple...
plane as day with a dead cxr, on any RF "monitor scope". Looks
like a small sine wave across both the top and bottom. Should
be a solid green bar.

### I haven't found any formulae for a C input filter HV
supply........ with 3 phase. I don't have access to 3 phase....
so never pursued it. It would be the ultimate setup. IF you
find anything... let me know... as I'm most interested. Somebody
is going to ask me to engineer one for em... so I had better
research it.

### I did see some info on C input 3 phase HV supplies some
where.... it's in Orr's older books.... but not alot of info.
Seems to me he had the 3 x primary's connected in a "Delta".....
and the 3 x secondary's tied in a.. "star". The rectifier set
up... if I remember, sorta looked like just 2 x diodes per sec
winding... one flipped around If I remember. The RMS voltage
per sec winding vs no load HVDC output is what threw me.
With say a 1 kv sec.... I'm positive... the OCV hv wasn't 1414
Vdc. [I may well be wrong with this.. just going by memory]

In any event... the entire concept looked cool .... which could
easily be implemented with either a 3 phase xfmr.... or 3 x
separate xfmrs. Dahl's diode boards for this appear to have
6 x legs for the entire mess.......... instead of 4 x legs for
single phase FWB..... which, incidently he rates at 18 A CCS....
using just standard 6A10 diodes [1 kv-6] diodes.

He rates a standard FWB.. with the usual 4 x legs at 12 A
CCS... using the same 6A10 1 kv-6A diodes.

Now 6 A x .8 V = 4.8 watts.... which would get VERY hot.
I experimented with mine.. in a test jig... just pumping low V
DC... and a variable lab supply + a 25 ohm-225 w resistor... and
found that the 1N5408 [1 kv-3A] would run luke warm with 1 A
CCS... and hot at 2A... and smokin hot at 3 A. Similar results
with the 6A10 [6 A- 1 kv]... runs luke warm with 2 A CCS...
hot
with 4 A.... and smokin hot with 6A.

Commercial rectifier assy's using these diodes... some of em
will blow 100 cfm across em.... if u want to run em anywhere
near maxed out.

I also tried paralleling 3A diodes for more current [and also
6A diodes] .. Done easily... and the current split is
virtually 50-50. So I don't understand the ARRL handbook insisting
installing series resistor's in each leg for balancing ? I
also tried paralleling two separate, identical bridge rectifier
assys.... same results.

One other note... Just by hooking a test clip lead on the very
1st and very last diode.. while doing my heating tests... I
found that the 1st and last diode ran barely warm.... while the
rest of em ran hot. The leads out each end of these diodes IS
the heatsink.... so don't cut em off short.... they either have
to go along aways horizontally b4 doing a right angle into the
board... OR go straight through the board... and keep going in mid
air below the board 1" to 1.5"

Later.... Jim VE7RF

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

--- In ham_amplifiers@..., "zerobeat40" <zerobeat40@>
wrote:

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

As I understand it, announcements of this group's existence on

the

AMPS group were somewhat censored.

Your understanding is incorrect. There were several announcements

of

this group, as well as the larger more-established rfamplifiers

group

on Yahoo that made it to AMPs. Everytime someone posted on this

group

that "my announcement did not get posted", I looked at AMPS - and

it

was, in fact, posted.

### DREAM ON. I checked 'amps' on contesting .com 3 times
now.... with a microscope [pulling up their archives]..... it ONLY
got posted TWICE..... once from Mike... once from Alek

later........Jim VE7RF

Yes, that is the distinct number of people who claimed to have
attempted to post it and claimed that it was not posted.

Thank you for the corroborration.

Z

--- In ham_amplifiers@..., "zerobeat40" <zerobeat40@...>
wrote:

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

As I understand it, announcements of this group's existence on

the

AMPS group were somewhat censored.

Your understanding is incorrect. There were several announcements

of

this group, as well as the larger more-established rfamplifiers

group

on Yahoo that made it to AMPs. Everytime someone posted on this

group

that "my announcement did not get posted", I looked at AMPS - and

it

was, in fact, posted.

### DREAM ON. I checked 'amps' on contesting .com 3 times
now.... with a microscope [pulling up their archives]..... it ONLY
got posted TWICE..... once from Mike... once from Alek

later........Jim VE7RF

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

On Oct 2, 2006, at 5:58 PM, pentalab wrote:

### Yes HSU. We were wondering why it took you so long to find
us !! LOL

As I understand it, announcements of this group's existence on the
AMPS group were somewhat censored.

Your understanding is incorrect. There were several announcements of
this group, as well as the larger more-established rfamplifiers group
on Yahoo that made it to AMPs. Everytime someone posted on this group
that "my announcement did not get posted", I looked at AMPS - and it
was, in fact, posted.

Z

On Oct 3, 2006, at 5:54 AM, ad4hk2004 wrote:

Rich I took a look... The resistors are L100J-20K rated 2850 volts
max.. It is a string of five in series, so I see no problem... Perhaps
you were thinking of a different resistor, but thanks for the heads up...

High value wire-wound resistors have a well deserved reputation for opening up - even when operated well within the mfg's max-V rating.

cheers, Denny

denny / k8do







Yahoo! Groups Links

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

Rich I took a look... The resistors are L100J-20K rated 2850 volts
max.. It is a string of five in series, so I see no problem... Perhaps
you were thinking of a different resistor, but thanks for the heads up...

denny / k8do

Hi Group,

Anyone have the schematic and hookup info for the Alpha 99 HV transformer that you could send electronically?

I have downloaded the manual from Alpha but it does NOT include any schematic or info on the transformer connectors.

Thanks in advance for your help!

73, Tony W4ZT
tony
at
w4zt
dot
com

Ummm, no... Thought didn't occur... I will do that but I unlikely I
will make a change...
One resistor got hot in the middle of the winding, bubbled the coating
over a distance of about an inch and a half, being exposed to the air
oxidized the nichrome wire and it finally burned in two... Then the
fireworks started with crap being arc sputtered all over the PS...
Being the RF box is in a different room of the shop than the radios, I
heard/noticed nothing until I happened to idly look the HV while in
receive... Eyes got wide and I hastily hit the main breaker on the
wall by my left hand (planned that way for stuff such as this) The
other 4 resistors look fine, no sign of overheating... I am going to
change out the whole rack of 5, but that is just because I'm an old
woman about minor things - spent part of my wasted youth maintaining a
herd of 100KW RF generators and a pinch of prevention stops a whole
bunch of lost production time...
It looks to me to be a manufacturing defect in the resistor as opposed
to deficient design... ( Brand was HEI 9352, possibly a spot welded
wire join in the winding? - dunno. )
I know contesting groupies go on about Henry's supposed design
deficiencies, but I have to say until this incident this amp has given
a dozen years of solid contesting service... The high voltage
stabilization is/was stiff... Since I don't jump from band to band in
a contest the slow tuning is not an issue... I have been happy with it...

denny / k8do

On Oct 2, 2006, at 5:58 PM, pentalab wrote:

--- In ham_amplifiers@..., "Hsu" <Jbenson@...> wrote:

Hi,
I have join the list.Thanks for many friends Invitate me to

ham_amplifiers.

Hsu

### Yes HSU. We were wondering why it took you so long to find
us !! LOL

As I understand it, announcements of this group's existence on the AMPS group were somewhat censored.

### You can talk about 811-A's all you want here. And nobody is
going to suggest boycotting Chinese made products, Chinese gov't,
or Chinese radio amateur's either !

Welcome aboard.....
Later.... Jim VE7RF








Yahoo! Groups Links

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

On Oct 2, 2006, at 3:25 PM, pentalab wrote:

--- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...>
wrote:

What is your reason for that large capacitor?
Are you using single phase at that power level?
I only use 2?F maximum or NONE in my large power supplies, so my
glitch resistors and magnetic breakers in the primaries of the
transformers is all I need

73
Peter, DF3KV

### You gotta be kidding us right ?? 2 uf or NONE !!

2uF in a FWB is enough for a 4-1000A at 6kV.

### here in NA... although 3 phase power [typ 12.5 kv /14.4 kv
and now 25 kv] is distributed all over town..... only one
leg /phase of that appears in residential area's.... where it's
dropped down to 240 /120 v [ they all use a grnded CT on the
sec]

### Typ pole pig xfmrs are 25/50 kva for multiple homes.. and
smaller for a single home in the countryside. How 16 homes
can all share the same 50 KVA xfmr [and all have "200 A"
service] is beyond me !

Indeed, and it's all because of greed. . During the recent heat
wave in Southern California, transformers were popping like popcorn
in residential areas because Southern California Edison originally
cut costs by installing transformers that were Way too small. For
example, on our block, a 50kva transformer supplies power to c. a
200kva max load. During one heat spell, the transformer got so hot it
broke a seam and started to leak coolant oil. Edison's fix was to
replace it with another 50kva unit.

### 3 phase 208v/120v is used for business's.... and
condominium's, apartment flats etc. Even there.... each floor will
only get 208/120 single phase power... per suite. They make
special 208 v electric base board heater's. Stuff like 240 v
electric stoves.. and 240V electric hot water tanks/ 240 v
electric clothes dryer's.. are used on 208 v.... and just take a
little longer to heat up.

### For a single phase RF deck that needs say 6900V @ 3A... a
bare minimum of 34 uf will provide barely 3% ripple.
A 100 uf filter will provide 1% ripple... and far better
DYNAMIC Regulation.

And nobody on the Rx-end can hear the difference, Jim.

...

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

On Oct 2, 2006, at 2:55 PM, pentalab wrote:

--- In ham_amplifiers@..., "ad4hk2004" <ad4hk2004@...>
wrote:

- busily changing out 20K ohm, 100 watt, resistors in a Henry 3K
Ultra PS.... Man a bad PS load resistor can sure contaminate
everything when it decides to go open winding and arcs, sputtering
crap onto other components...
It took a bit of sleuthing to find the correct resistors for
replacing... Turns out Newark has em in Ohmite brand...

### I looked at the 8k/3 k ultra manual I have [same manual does
both amps]. On the 8k they use 5 x 20k-100w resistors. Diss is
a whopping 300 W CCS..... presumably so the resonant choke filter
will work.

That's what I presumed too until a friend did some tests with a Dahl
resonant choke filter. He discovered that significantly less bleeder
current than Henry Radio used would keep the standby potential from
rising more than usual.

On the 8 k.. they used a 6000 V xfmr. .9 x 6000 =
5400 vdc no load.

### here's the kicker. IF just one bleeder opens up... the OCV
plate V shoots UP to a whopping 6000 x 1.414 = 8484 V !!!
Now the poor 3CX-3000A7 [rated for 5 kv] won't like it.... nor
anything else in the amp. You are lucking you didn't blow up ur
3k ultra.

An 8877 will easily stand 10kV on standby. The main danger from 8kV
is to the filter capacitor.

### I gave up on choke input HV supplies yrs ago. The
resonant choke idea although a good one... is not so simple to
implement.

Agreed, but for A?, RTTY, long-winded AM broadcasting, and for guys
who like to "pump iron", it's ideal.

## My feeling is one is better off to use a C input filter. The
8 k ultra's plate xfmr is flaky at best. They could have used just a
3800 vac xfmr..... which would require LESS turns on the sec
winding.... which in turn would mean the xfmr coulda used bigger
ga wire in the 1st place.

### Dahl does a roaring business selling a 127 lb 10 kva
replacement xfmr + mating choke for the 8 k ultra. Stock, the
8k is only good for 2 kw out CCS rtty/ 3.5 kw pep cw/ssb....
then in real fine print on the schematic it sez..."200 w in... 5kw+
out".

A Dahl 127-pounder with a C-filter is good for at Least 30 out on SSB
using one 8281 / 4cx15,000 in AB1.

### IMO... why put a ton of weight.. in the form of a choke in a
HV .... better to put the added weight into the plate xfmr in the
1st place... but that's just my opinion.

I agree for SSB.

...

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

To see how much ripple was noticeable on the air, a friend put a 4-1000A on the air with a 6kV FWB PS running a 2uF C-filter. I could not hear any ripple -- at least on
SSB. AM would likely have been different.

On Oct 2, 2006, at 9:50 PM, Jan Erik Holm wrote:

Then, if we talk 3-phase supply and 6-puls rectifying,
lets say around 5 kV DC potential, how much glitch C
is needed to achieve 1.5 percent ripple?

Forgot how to calculate it, must dig out books
to do it.

73 Jim SM2EKM
---------------------------------------------
pentalab wrote:

### You want to shoot for 1 to 1.5% ripple in a C input HV
supply.... then you can also be assured of good dynamic reg.

Yahoo! Groups Links

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

On Oct 2, 2006, at 5:11 PM, Hsu wrote:

Hi,
I have join the list.Thanks for many friends Invitate me to ham_amplifiers.
Hsu

Welcome to the uncensored amplifier discussion group, Hsu.

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

On Oct 2, 2006, at 3:50 PM, Bob Green wrote:

OK, I've got the grids of the 572's grounded through 33 ohm resisters in
parallel with 940pf of capacitance. No smoke!!! Plates are NOT glowing!! I'm
getting a reading of approx 80-90 ma of plate current as read on the meter.
This looks normal, as far as I can remember. Things are looking up!

I must be really dense, but I still don't know how to hook up the meter to
read grid current though. Can anyone help, PLEASE!

Bob -- Grid current eventually gets back to the negative HV. It flows through the 33-ohms, to gnd, and from gnd through the grid-I meter shunt-R to HV-neg.
Typical values for the shunt-R are c. 1.0-ohm with a small, few k-ohm calibration resistor in series with the meter to make it read accurately.
cheerz

73,

Bob Green W6BBL
w6bbl@...

All email scanned by the latest update of Norton Anti-Virus 2006 and is
certified to be 100% virus-free.




Yahoo! Groups Links

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

You can look here:



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

Bob Green wrote:

Then, if we talk 3-phase supply and 6-puls rectifying,
lets say around 5 kV DC potential, how much glitch C
is needed to achieve 1.5 percent ripple?

Forgot how to calculate it, must dig out books
to do it.

73 Jim SM2EKM
---------------------------------------------
pentalab wrote:

Jim,

Yes, your correct on the 3-5% ripple for the plate tranny. I was
thinking of the low voltage DC supplies when I wrote that. Sorry, my
faux pas. The formulas are written around 5% actually since they feed
supplies for all types equipment including test equipment like RF
generators, etc. I agree the cleaner the better, but that can be hard
to do the lower you go under 5%-3%. More C = More clean, but more
current from the tranny and through the rectifiers. Manufacturers
design for the bare minimum over the cost of the transformer, and the
caps IMHO.

The formulas was for the rms tranny current for the secondaries. In
other words, it takes 1.8 times (1.8 by Stancor and others, and 2X for
100% duty cycle) the DC load current for a C input full wave bridge at
around 5% ripple or less (Hammond says 1.6 X). Now you multiply that
by the secondary voltage to get the secondary power, then multiply
that by the losses (wire I^2 R and core) found by the efficiency (for
large cores around 85%), and that's the primary power since primary
power = secondary power plus the losses. After that, multiply by the
power factor which is generally 0.9 according to the "Reference Data
for Radio Engineers" book.

On the resonant choke, I had read a little more since that
comversation, and seen the part about designing for a bit above 120 Hz
somewhere on the net. To me, it's more worry and complicated than what
it's worth. I'll bet it never works the same between each amp they
build either. I also never did complete the project after all I read
about it. Matching the choke to the caps is about the only way to do
it. Also, one would have to run the amp so the rated current would
always be where it resonates, or it wouldn't do any good.

The reason why the Hammond trannys would run hot is probably where
they spec them smaller than the others using the 1.6 X DC current
figure. They're the only ones that do it I've seen from a Ton of
research I've done on the subject. 1.6 would probably be ok for SSB
only.

BTW, The group at Wikipedia that deleted the transformer info had me
to do a complete new page named transformer design. Take a look,
though I've not finished it completely. There's 1-2 from the
transformer page helping me with it after all the discussions went
over. I'm only going to do the power transformer portion. For audio
and RF, others can do it. See;




Best,

Will



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

--- In ham_amplifiers@..., "craxd" <craxd1@> wrote:

See below,

Jim,

My guess for the reason Henry used a choke input power supply was

that the transformer can be smaller than one for a capacitor input
by a good bit. Most transformer manufacturers give for a choke
input, the rms current is 1.2 x DC current, and for a cap input it
is 1.65 (Hammond only) to 2 X, with most saying 1.8 X.

### I'm assuming you are refering to PRI AC current ?? Dahl
sez for his hypersil C cores... take the DC INPUT power and
multiply by 1.21 to calculate PRI KVA power. [21%]. 11% of
that comes from a power factor of .9 and the other 10% comes
from cores losses. So what's he's telling me is that the ratio
of KVA input power to DC watts is 1.21

### When I measure these old Hammond's [80 lb units designed for
choke input supplies, IE: high reactance types] when used in a C
input filter set up... I typ get pri KVA is always 1.35 x
higher than DC input watts [load of the amp] .

### BTW... all these old hammond xfmr's used a 2 x choke setup....
all of em. The 1st choke was I think, a hammond fixed choke...
followed by 2 x oil caps.... followed by a hammond swinging
choke... followed by another 2 x oil caps.

### These 80 lb Hammonds were typ 3450-0-3450... and had a 0-110-
115-120 V primary. They were all rated at 2.2 KVA . DC wise....
they were rated for 3000 Vdc @ 500 Ma CCS.... and 750 ma
ICAS. Sec DC resistance, end to end was typ 135 ohms.

### One of em... in C input filter... would run hot as hell...
running a single 4-1000 @ 1900 w pep output. Two of em would
work [then u could run em on 240v} Total weight 160 lbs. Two
of em would again run scorching hot.. with a 2 x 4-1000 amp.

### Their biggest drawback is the 3450-0-3450 sec... and the 120
v primary. The turns ratio is a whopping 6900/120= 57.5 !!




The difference is the rms voltage of the choke input transformer
has to be higher than that of a cap input to match the same DC
voltage. A resonant choke has to resonante at the peak current draw,
so the cap and chokes (Lcrit) critical value has to match that
figure. The only problem, there's no resonance at idle current. You
still get the filtering of the choke, it's just not resonant to
where the ac portion would be killed down like it is at the peak
current. So, Lcit has to be selected at the peak current. See a
copy below from a conversation between Peter G3RZP and I from the
Amps archives.

On transformer regulation, the voltage sag I've found on most all
transformers in better built amps runs about 12% to 14% (I always
figure 13%). I've never seen the 10% value listed in most books.
Heathkit had worse regulation than this in a few models starting

at

15%, and one at 30% if I recall. I've never heard of 9% regulation
anywhere. I guess you could reach that, but you'd have to have a
wheelborrow full of caps, and a lot bigger transformer than need

be.

### And big wire to the main panel.. and big contactor's etc.
A lot of this V sag is coming from the HUGE peak current every
8.3 msec x dc resistance of all the wiring, contactor's ,
breaker's,lugs, etc. All that stuff has to be oversized.... or
bye bye V regulation.... never mind the plate xfmr/caps.

You have to watch at sizing transformers by weight as that always
don't hold true since it has to do with the design of the core. If

you have a core with a larger window, one with a smaller, and both
with the same weight, the smaller would have more core area and
thus be capable of more watts out. This holds true especially in C-
cores. I always did wish Bill Orr would have never said something
about using weight for transformers in his book.

### agreed. I wish Orr would have NEVER mentioned the
nonsense about.. "IVS ratings".... Intermittent Voice
Service !!! which was based upon unrealistic low duty cycle
figures of 25 % [ it's 50% average on any plate current meter].
They also factored in.. I talk... then listen for 15 mins....
during a 5 x way roundatable. They also FORGOT the idling
current from the tube[s] ... which throws all the cals out the
window !

### Don't laugh. TEN TEC still brags about their 7 kw IVS
rating of the xfmr in their Centurion 2 x 3-500Z amp. They
rate the xfmr at 3.5 KVA CCS. The amp is one of these "almost
legal limit" jobs by the factory/QST. It will NOT do 1.5 kw
output RTTY. It's designed to do 1.2 kw output PEP on ssb...
that's it.... just like a stock SB-220.

The problem with a bunch of capacitance is when something shorts,
there's a lot of joules of power released at once which can

destroy more stuff than need be.

### Easy fix.... install a 50 ohm glitch R. For a 7900 V
supply with 135 uf filter cap.... and running up to 3 A of
plate current... we used a pair of 100 ohm 225 W CCS wirewound
resistor's in parallel. These are cheap... right outa the
mouser/digikey catalog. The glitch R assy.... is PRECEDED by
a Buss 3 A HV fuse [HVU Sandfilled type]

### I can short the +7900 to chassis.. or anything else.... just

a

'minor' flash from the sandfilled fuse. Nothing gets blown up.
We tried it 12 times so far in this latest project.


A ripple factor of 10% or less is all one really needs. If one
sticks with the published formulas by the transformer
manufacturers, you can't really go wrong as they did the

tests to come up with them.

### 10% ripple would sound like crap over the air ! Both Orr
and ARRL always have quoted 5% max ripple for cw... and 3%
for SSB. Those are still the bare minimum's. A L4B is 3%..
at max load.... so is A SB-220 TL-922. Heck, back then the
biggest lytic was only 200 uf @ 450 V.

### You want to shoot for 1 to 1.5% ripple in a C input HV
supply.... then you can also be assured of good dynamic reg.

Quote from Amps;

. I've never used a swinging choke in
a
tuned choke system, though.

### It would NEVER work. You want the choke and resonating cap
to resonate a BIT above 2 F... or aprx 125 hz. You will never
see a swinging choke in a resonant choke set up. John Lyles sez
they actually ship the resonating caps to the choke builder... who
designs/builds the choke around the caps.



. If you get the wrong resonant condition, you

can get enormous voltages built up too, so this is not an

exercise for the guy who isn't experienced in working on HV
circuits. Tom, W8JI, has a frightening story about that, which
you'll find somehwere in the Amps>

### W8JI scrwed up.... and thought for max ripple reduction...
you resonate the entire mess at 120 hz ! If you do that... peak
voltages will soar, and the biggest flash over you will ever
see. The trick was to resonate it slightly above 120 hz...
around 125-128 hz. I read the story. All he had to do was
slightly DECREASE the cap value... the 2nd time around. There was
no 2nd time around.

## You will notice in the 8K/3K manual... they use 3 x resonating
caps in parallel with the choke... when power is 50 hz. When
on 60 hz... one cap is removed... and only two are used.

later Jim VE7RF