开云体育

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

--- 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

### 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

--- 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

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

All,

At one time, I had the address and phone number for a supplier around
Dayton or Cinci Ohio for transformer related supplies. They carried
paper, varnish, wire, hardware, and lams. EIS I know about, but they
dont carry lams. Does anyone on here know who that might be, or have
anyone that they might recommend? If so, please let me know off the
list. I know there's a lot of suppliers around Los Angeles, CA. That
would be no problem. Thanks in advance.

Best,

Will

craxd1 at cerizon.net

For higher power I use 3/8" on 160m, 1/2" on 80+40m, followed by ~3/4" on
the higher bands.
I do my silver plating with a homebrew mixture.
When I had no other stuff on hand, I once used sugar to fill the copper tube
before winding it, gave a nice smell after firing it up at high power, as
not all went out that easy ;-).
For much less then 8K I built 6 monobands amps 5K out.
I always prefer tetrodes...

73
Peter


________________________________

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

### LOL ! I typ use 1/4" 3/8" and 1/2" [6-9-12 mm od]

### chek out what Multronics wants for say 1/2" tubing coil
stock... like a 14 uh coil.... you will gag.. and have sticker
shock. $8,000 for a new alpha. I can buy a helluva lots
parts for $8 K.

### You don't need much tubing to wind a typ tank coil. I used
1/4" for the 160m portion...... 3/8" for the 80-40m coil.....
and 1/2" for the 20-17-15m coil. Anybody who is thinking of
using these big triodes on 10/12 m... is well advised to use 3/4"
tubing... or 1.5" wide strap. [typ 2-3 turns.. 3" ID used on
10/12m]

### They are easy to silver plate too... with "cool amp" from
Ore. 3/8" and up will flatten on you, when wound... width is
greater than the height. [looks cool] If u want it perfectly
round..... fill the tubing with either rocksalt.. or sand b4 u
wind the coil. Use an air compressor to blow out the sand when
done. With rocksalt..... just toss the completed coil in
water... and let it disolve.

Later....Jim VE7RF

________________________________

From: ham_amplifiers@...

<mailto:ham_amplifiers%40yahoogroups.com>
[mailto:ham_amplifiers@...
<mailto:ham_amplifiers%40yahoogroups.com> ]

On Behalf Of pentalab

and it's all dirt cheap....just like copper tubing.

See below,

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

### 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. 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.

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

## 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".

### 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 had some 3 k owners e-mail me a while back.... they were in
the 10m contest [where both cw/ssb modes are used the entire
weekend]. The poor fellow had forgotten to change the plate V
from High... to low... when switching from ssb... to cw. The
HV supply bit the dust shortly afterwards. [smoked plate xfmr]

## Henry has gone through so many plate xfmr manufacturer's, I have
lost count. The last supplier for the 3k/8k was ECA. And just
b4 Henry went "outa business"... they dumped ECA as a plate
xfmr supplier !

## I know several fellows who bought the Henry 16 uf - 7.5 kv
rated oil caps.... used em in 4-1000 amps.... and blew up the caps

!

With the proliferation of the newer low esr lytics out there
[loads of em on the surplus market].. for a new hb project, they
can't be beat. The latest bunch I got are 50 miliohm and 10 A
CCS ripple current rating.... small things too.... 2500 uf @ 450
vdc... and just 2" diam x 4" long.

## It just seems nuts to me to suck 300 W ccs of bleeder...
then another 150 ma @ 5200 Vdc on idle [8k] on top of that.

### The 8k drops from 5400 vdc to 4700 vdc with a typ load. It
weighs a whopping 350 lbs too ! Since the alpha 87-A will
do 1.5 kw CCS... and the 8k will do just 2 kw CCS... I'd say
Henry just lost it... in the weight dept.

### BTW... a Dahl 10 KVA CCS xfmr weighs.. "just 127 lbs"

Later......Jim VE7RF

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. 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.

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.

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. 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.

Quote from Amps;

Because the critical choke inductance in a choke input filter varies
inversely with the current, the swinging choke can have less air gap
i.e.
less reluctance than a non swinging choke. This means that it needs
less
wire for any given inductance, and so can be smaller. As the air gap
is
reduced, so the flux density in the iron goes up - less reluctance -
so
the number of ampere turns needed to start reducing permeability
reduces.

Now look at the numbers. Suppose we have a 2kV supply with a bleeder
current of say 50mA, which is still 100 watts of heat.

Now Terman gives Lcrit>R/1130 = 40,000/1130 = 35.4 Henries for a
60Hz
single phase full wave rectifier.

At 1 amp, however, we only need 1.77H.

So you can see why a swinging choke is used.

Interesting question: if the transient performance is so bad, why were
swinging chokes considered OK for Class AB and B audio amplifiers used
as
modulators in AM tx's?

Anyway, back to the point.

At 120Hz, the reactance of 35.4H is 26.7K

If we used a 20H choke, the reactance is 15.08K. Now shunt that with
0.08
microfarad. The result is


1[1/(-jXc) + 1/(jXl)] equivalent to 221.2 Henries, so we've made a
small
choke look like a much bigger one.

the resonant frequency is 125.8Hz. ( f = 1/ 2pi. rt LC)


Now this is all rather idealised insofar as no account has been taken
of
the choke resistance, which will modify the resonant frequency
(resonance
being defined as the frequency at which the circuit dealt with as a
one
port looks purely resistive) and the effective inductance. But you can
see
that adding the 'tuning' capacitor makes the choke look like a much
bigger
choke. Now if a swinging choke is used, as the current increases, the
choke
inductance drops, but that doesn't matter as long as the circuit still
offers more than critical inductance.

My suspicion is that a swinging choke provides worse transient
regulation
because when the load decreases, until the domains within the magnetic
material can start de-aligning, i.e. getting further away from
saturation,
the choke critical inductance is too low, so the volts start to swing
up.
In any case, you have a parallel tuned circuit with varying current,
so
there will be a biggish transient. I would have thought that a fairly
big
output capacitor would cure this from the viewpoint of the load, but
the
rectifiers could see a large PIV. I've never used a swinging choke in
a
tuned choke system, though. Nevertheless, all chokes with iron cores
change
inductance to some extent as the current varies - some more than
others.

As Will said, tolerances mean that very careful choice of components
is
needed if you are to be certain that the choke is tuned HF: if you
tune it
LF, it will look like a lossy capacitor and the whole thing will
revert to
a capacitor input filter. 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, W4JI, has a
frightening story about that, which you'll find somehwere in the Amps
archives. I find a Variac very useful at this early stage of the game:
later, when you want to get realistic loads on the PSU, the Variac
isn't
such a good idea - they're not renowned for their regulation.

73

Peter G3RZP

End quote.

Best,

Will

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!

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.

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

Copper tubing is quite expensive overhere now.
10mm diameter is 3,60 Euro/m, 18mm is 6,40 Euro/m.
Prices are for small quantities of course.


73
Peter

### LOL ! I typ use 1/4" 3/8" and 1/2" [6-9-12 mm od]

### chek out what Multronics wants for say 1/2" tubing coil
stock... like a 14 uh coil.... you will gag.. and have sticker
shock. $8,000 for a new alpha. I can buy a helluva lots
parts for $8 K.

### You don't need much tubing to wind a typ tank coil. I used
1/4" for the 160m portion...... 3/8" for the 80-40m coil.....
and 1/2" for the 20-17-15m coil. Anybody who is thinking of
using these big triodes on 10/12 m... is well advised to use 3/4"
tubing... or 1.5" wide strap. [typ 2-3 turns.. 3" ID used on
10/12m]

### They are easy to silver plate too... with "cool amp" from
Ore. 3/8" and up will flatten on you, when wound... width is
greater than the height. [looks cool] If u want it perfectly
round..... fill the tubing with either rocksalt.. or sand b4 u
wind the coil. Use an air compressor to blow out the sand when
done. With rocksalt..... just toss the completed coil in
water... and let it disolve.

Later....Jim VE7RF

________________________________

From: ham_amplifiers@...

[mailto:ham_amplifiers@...]

On Behalf Of pentalab

and it's all dirt cheap....just like copper tubing.