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On Nov 19, 2006, at 7:32 AM, pentalab wrote:

--- In ham_amplifiers@..., Tony King - W4ZT <w4zt-
060920@...> wrote:

Which MOV's do you use and where do you get them?

### From Mouser... Digi key has em as well... aprx 2" tall x
1/2" thick x 2.75" wide base. Those are the 130 v units.
The closest ones for the 240 V service are 250 V rated. IMO..
250 V rated Mov's are cutting it too close.

Perhaps it might be a good idea to read the specs on the 250v-rated MOV's, Jim.

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

On Nov 19, 2006, at 7:47 AM, pentalab wrote:

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

On Nov 19, 2006, at 5:08 AM, Peter Voelpel wrote:

Since I prefer single capacitors as a blocker,

RICH SEZ...Single cap DC blockers have the advantage of Not

exhibiting a VHF- resonance between two or more paralleled
capacitors.

### which never happens.... IF you parallel em with WIDE AL/CU
plates on both sides. 8 x 200 pf HT-57's exhibits no
problems at all.... ditto with 6 x 500 pf HT-57's. ....or 4 x
500 pf HT-59's.

Are you saying that there is no resonance when two caps are paralleled?, or are you saying that in the amplifiers you built you have never had a problem with such a resonance? I know of a case where two caps were paralleled for the DC blocker where the VHF resonance caused a problem, which is why I brought the subject up.

### I looked at the big Draloric's, and the UK eq. For SOME
layouts... they seemed awkward to mount... cuz of the large
diam. I think the 10 kv - 60A 2000 pf ones I was looking at a
while back were 5" diam. In my case, the HT57/59's were
easily obtainable... and the 57's come in 10/15 kv... the 59's
come in 15/20/25 kv. The 50/58's come in 5/7.5 kv.

HEC makes some reasonable sized 25A or so units.

### Dunno how much safety factor one wants in a plate block
cap.... I'd like 50% min. Use what ever is available.
Dralorics here, surplus and also used... are NOT cheap.

I think I paid c. $120 each for some 25A-rated HEC's.

Later... Jim VE7RF

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

We had a 37 KVA unit here to support 6 houses. one hot?night when it?popped? they hung a 50 KVA

pentalab wrote:

Bob,

Who is asking for any retractions?

I didn't say to wire anything a certain way, just pointed out the
constraints I face and the considerations given when we wire up
something under the NEC code here.

I know you're lying: Ha, ha! I've seen your QTH.

You've got knob and tube wiring with knife switches and bare aluminum
#16 AWG on ceramic nailed-in insulators on the studs.

(I'm just pulling your leg, here, Bob. Your house will probably not
burn down from octopuses.)

In Kentucky I installed an Appleton plug for the gen set on the side
of the house (200 A) and ran a battery charging outlet with a twist-
loc right above it. However, inside, it's a different story. No ATC,
just two different breakers. I didn't want the gen set kicking in
when I wasn't home: Lemme decide on my own.

As for the shack, I run 60 foot 10/3 SOOW cords on four different
circuits from the sub panel, right through the laundry room and
around the office to the bench. All the grounds and grounding goes
through a wall-mounted MGB that has a 4/0 green stranded going right
out to the SAGB and everything is bonded.

I'm afraid to tear into the walls. I don't know what I'll find.

The gen set's wired similarly: The 4X2 AWG is an SOOW cord, but the
frame is directly bonded to the EGR with a dedicated rod right off
the porch.

We already have an old washing tub on the porch, and a 10 cent Coke
machine from the year Gimel, so the gen set fits right in with the
Tobacco Road decor. Hey, it's Eastern Kentucky.

The main antenna disconnect switch is from a friend's house in Elmira
where he yanked the K&T wiring when he renovated. Ceramic, brass, 5/8
blades: a beauty from 1900.

See ya!

Hal

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

On Nov 19, 2006, at 5:08 AM, Peter Voelpel wrote:

Since I prefer single capacitors as a blocker,

RICH SEZ...Single cap DC blockers have the advantage of Not

exhibiting a VHF- resonance between two or more paralleled
capacitors.

### which never happens.... IF you parallel em with WIDE AL/CU
plates on both sides. 8 x 200 pf HT-57's exhibits no
problems at all.... ditto with 6 x 500 pf HT-57's. ....or 4 x
500 pf HT-59's.

### I looked at the big Draloric's, and the UK eq. For SOME
layouts... they seemed awkward to mount... cuz of the large
diam. I think the 10 kv - 60A 2000 pf ones I was looking at a
while back were 5" diam. In my case, the HT57/59's were
easily obtainable... and the 57's come in 10/15 kv... the 59's
come in 15/20/25 kv. The 50/58's come in 5/7.5 kv.

### Dunno how much safety factor one wants in a plate block
cap.... I'd like 50% min. Use what ever is available.
Dralorics here, surplus and also used... are NOT cheap.

Later... Jim VE7RF

--- In ham_amplifiers@..., Tony King - W4ZT <w4zt-
060920@...> wrote:

Which MOV's do you use and where do you get them?

### From Mouser... Digi key has em as well... aprx 2" tall x
1/2" thick x 2.75" wide base. Those are the 130 v units.
The closest ones for the 240 V service are 250 V rated. IMO..
250 V rated Mov's are cutting it too close.. since my line V has
been as high as 247.2 V in summertime. Instead I use the 275 v
rated Mov's from Dahl.... made by "movistar".... almost same
dimensions.

### ACROSS poles of contactor's, you want 250-275 V rated
Movs... and not 130 v ones. IF you use fuses in each leg of
the 240 v.... and just one opens... there is 240 v across the open
fuse. Same deal with a contactor's poles.

## I install the 130 v rated Mov's between each hot leg and
grnd.... right at the plate xfmr primary.... and 2 x 275 v rated
mov's, in parallel, directly across the plate xfmr primary.

### You can get MOV's from mouser/digi key up to 1 kv. You can
also series / parallel em too. Some will use 6 x series 1 kv
mov's across the SEC of a 5200 v plate xfmr. Some commercial
diode FWB's.. whether single/3 phase... will use a MOV across
each diode..... and no cap/resistor. Most commercial bridges
will use 3 x PIV for total number of diodes.

You do all you can and something can still fail but we've gone

from jumpering a fuse with copper wire to worrying about the
protection circuit failing.

## yeah, I know. I'd trust a proper size fuse 1st... b4 any
protection circuits. Both of em together is the real answer.

### seems to me the 2 x triode boards wouldn't handle 3-4 A

of

normal anode current... but might be modified ?

Look at Paul's board... you can set it up with any external shunt

for

detecting a fault. Use the board to control any kind of contactor

you have.

#### I cringe when I see a full bore normal load being opened
off by a relay/contactor. Trying to open off an even bigger load
during a fault condition is even more demanding.

### Watch the relay/contactor... when opening it off... while
sucking 100+ A key down ! Imagine this again.... but with
2-4 x more current during a fault condition. Then toss in a
high value C filter for fun. Peak current on the 240 V line
every 8.3 msecs is 4-6 x normal operating current as is... never
mind a fault condition.

### I just wanted to keep it simple. Any electronic protection
would have to be in addition to properly sized HV fuses and
primary breakers.

And if your friend had used a correctly sized fuse, it wouldn't

have been an issue.

#### Correct. Which was the whole point of the title in the
post. They also ran out of 750 Ma fast grid fuses one night.. and
stuffed in some 3 A fuses ! If they had lost HV.... the grid
current would peg when driven [normal]. The 750 ma grid
fuse woulda blown asap... and input swr rises to infinity...
and IPA/Xcvr shut down. With a 3 A grid fuse, they
woulda damaged the grid.

### frying a pair of 225 w glitch R's is one thing... frying an
expensive tube is another...esp when it's totally unwarranted.

Well, this thread started with your description of a failure

caused by

your friend using copper wire instead of a real fuse. There is no

device

you can install that can second guess someone that is going to

drop a

copper bar in as a fuse. Everything we do is done with the

expectation

that the original circuitry will be used as designed. Once part of

it is

defeated, then all bets are off! ;)

### agreed. I have no control over my buddy's amp. I can just
make a suggestion...that's it. I think once they blow stuff
up from oversizing.. that they probably won't do it again. A
few spare correct size fuses is cheap insurance. If a fuse
blows..... don't put in a bigger one... find the reason it blew !

Later... Jim VE7RF

73, Tony W4ZT

On Nov 19, 2006, at 5:08 AM, Peter Voelpel wrote:

Since I prefer single capacitors as a blocker,

Single cap DC blockers have the advantage of Not exhibiting a VHF- resonance between two or more paralleled capacitors.

I always use Draloric or Rosenthal caps, they are available at all kind of
capacities and voltages.
The are also very nice caps from Russia on the market with high values of
kvar.
Sometimes I also use mica caps by Jahre which are small and powerful, those
are harder to obtain

73
Peter

________________________________

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

### Me, I just use normal HEC HT-57's.... and HT-59's. I also
have looked at Draloric's and similar HEC block caps... these
ones look like aprx 2000 pf @ 10 kv, 60 A CCS @ 32 mhz....
and are aprx 3-5" diam.
...

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

On Nov 19, 2006, at 5:13 AM, pentalab wrote:

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

### Why don't u take some of that 4 wire home depot 8 awg...

and parallel em into 2 pairs.... eq ga is then 5ga.

RICH SEZ...And throw away the extant 4ga. wire?

#### The above was a joke. IMO ur 100' length [200' loop] of
4 ga wire is WAY too small for a 4x10.

Jim -- Do you design your amplifiers for A0 or for SSB?

4 ga wire isn't
even rated to handle 110 A.....never mind the 4-6 x that
current.... every 8.3 msecs. Calculate the PEAK current drawn
from the plate xfmr pri on a huge C input HV supply... and you
will see why I use big everything, including wire, contactor's,
etc.... from 200 A main panel to pri of 253 lb Dahl plate
xfmr.

Wouldn't a 900-pounder be better?

Duncan's pwr supply modeler.. PSUD-2 comes in handy for
this stuff. It also has 2 x methods of calculating plate xfmr
pri IMPEDANCE. Z is used to calculate peak pri current drawn...
not simply plate xfmr pri dc resistance.

I did the calculations for the 8170 amplifier with Ohm's Law. The calc. peak mains current was c. 300A. The measured result was 1200v- pk into 50-ohms on SSB.

#### 3/000 CU from main 200A panel to HV supply is what's
really needed. Snip a few strands to make it fit the 100 A
breaker at EACH end.

later... Jim VE7RF

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

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

On Nov 19, 2006, at 2:59 AM, pentalab wrote:

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

wrote:

...
RICH SEZ.... A 20kV rated C to block 7000V DC sounds like over-

engineering since the actual AC potential across the blocker is
minimal.

#### Rich... Jenning's engineers tell me when using either fixed
glass/ceramic vac cap as a PLATE Blocker.... MIN V rating of the
FIXED vac cap has to be a MINIMUM of 3 X No load plate V......
other wise u get "whisker's" growing on the OFC plates on the
cap..... which will REDUCE the caps V rating.

RICH SEZ... So why does the statement I quoted in the Jennings

catalog on p.4 about DC operation state otherwise?

#### Dunno. Eimac sez the same thing, de -rate vac caps to
1/3 for plate block use ! The 11m ops also highly agree. The
11m ops tell me if they try and use a 16 kv test rated fixed vac
cap with 10.5 kv dc on it..... it will eventually arc.

### other than 11m ops... I never see fixed vac caps used as

plate

blockers.

RICH SEZ... I do, Jim. Even 500pF is plenty for a DC blocker at

1.8MHz (XC = 190- ohms) in typical amplifiers since RL is in the
kilo-ohmS range.

#### No way. 500pf = 176 ohms of XC. IF the fixed VAC cap
can handle the RF current at 1.8 mhz.and plate load Z of tube is
HIGH.. and it doesn't screw up the tuning too much... it might
work. Big metal tube amps have plate load Z's of 900-1300 ohms.

11m ops don't need much C for 11m... 100-250 pf max
is what they typ use. Their requirements are for a plate block

cap

that handles LOTS of RF... esp for 4x20's, etc.

RICH SEZ... Tom Rauch apparently knows a Ham who mistakenly used a

100pF DC blocker in a homebrew amplifier. The amplifier produced
the expected output from 1.8 to 28 MHz. Sometime later, when a
friend was being shown the amplifier, he noticed that there were
only twp zeros after the 1 on the blocker cap. When a 1000pF cap
was substituted for the 100pF cap, the output did not increase
although the tuning changed slightly on the 1.8MHz band.

#### yeah, I heard the same story.. plus another one...except it
was 150 pf.....and in both stories,it was a ceramic doorknob
cap... NOT a fixed vac cap. I wonder if anyone ACTUALLY measured
it with a LCR meter ?? I have measured doorknob caps that had
measured values out by a factor of 10... compared to the stamped
rating on the cap. So unless Rauch's buddy actually measured
it, we don't know what it was !


#### 100 pf = 884 ohms XC [1.8 mhz] gimme a break !

### Stick a single 100 pf HT-50/58 cap in any 1500W amp....
run it at 1500 W RTTY/FM on 1.8 mhz for say 20 mins.... and
let us know what happens.





### A 3x6 has a 1100 ohm plate load Z.. when run full bore.
You don't wanna use a 100 pf cap.... including a vac cap.



### The plate block cap has to be able to handle the RF current..
without cooking.. so u gotta look at it's CCS rating... vs freq.
Ceramic caps don't handle much RF at 1.8 mhz... then again.. they
don't have that much RF through em on 160m. On 10m, the RF
through em is wicked...esp with metal tubes.. with lotsa stray
anode to chassis C..... or even worse in schemes that use NO C1
cap.. and rely on tube C.

### with big metal tubes... plate load Z is always LOW. You
need plenty of plate block C... simply so u don't screw up the
tuning on 160m..... and also so you have a high enough current
rating on 10m.

### a 100 pf doorknob cap wouldn't last 30 seconds in a 3x3
amp....try it urself.

later.... Jim VE7RF

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

--- In ham_amplifiers@..., "Robert B. Bonner"
<rbonner@...> wrote:

If I ever do build that 30 x 40 garage I will probably put in a 400

amp panel out there and sub feed the house. That 200 Amp service is
pretty busy.

### My electrician buddy said 240V 400A service was
available...and "no sweat". 400 A = 96 Kva ! 200A = 48 Kva.
I still don't get it. I have "200 A service".... and SO do my
15 neighbours... all hanging from the SAME 50 Kva pole pig ! Some
of my neigbours have a secondary suite in their homes... with a 2nd
elctric stove, etc.

### since we all got natural gas back in 1992... most of the
electric hot water tanks and oil furnaces have gone bye bye...
reducing the overall load..a bit. I still don't see any natural
gas clothes dryers..yet. Back East, they all have em... plus
gas ranges. My hot water tank, fireplace, and furnace all run on
natural gas.

### Bottom line is... when I smoke the pole pig at dinner time one
night..... I guess I can just whine to the pwr co... and say .."I'm
supposed to be getting 200A CCS service... so where is it? "

### The biggest pole mount pole pig I have seen is 100 KVA. But
these were special one off units...designed to drop 25 kv down to
12.5 kv..... then 12.5 kv into our vault xfmr at work... where the
vault xfmr dropped it again to 208/120. This is all 3 phase... and
both the 3 x old 75 kva xfmr's.. and the 3 x new 100 kva xfmr's
are huge... when u see em on the grnd. Every time I see 3 x
75/100 kva xfmr's.. all on the same pole, I cringe........ the
weight is massive.. as in 2 tons.

### anything above 100 KVA per phase... and it then goes
on the grnd.

Later... Jim VE7RF

pentalab wrote:

--- In ham_amplifiers@..., Tony King - W4ZT <w4zt-
060920@...> wrote:

Jim,

Don't you think that if a properly designed fault detection

circuit similar to the triode and tetrode boards available today would have caused a primary circuit shut down saving the glitch resistors from becoming a smoking pile?
### Partially agreed. Seems to me the 2 x triode boards available, are based on using an external 24 vdc DPST RELAY... whose contact's are in the 240 v primary. I don't see any 24 vdc RELAY's... with contacts rated for 100-400A. AC contactor's on the other hand are all either DPST-DM or TPST-DM.... the "DM" means 'double make'.... IE: essentially each pole is two sets of contacts in series.... with an input lug... output lug... and a huge bar on top that comes crashing down on the input/output.

As you said below, simple modifications will control any contactor you want to use.

### The DM arrangement is used [vs a dpst relay] simply cuz a DM will break the arc into two arcs = essentially zero arc....
[when trying to break a full bore load from a xfmr/motor] ### I never see giant bolt down MOV's across the in/out poles of any contactor's in commercial service.... but I always install the big bolt down MOV's across all the poles of my own contactor's in HV supplies anyway. The MOV's.. if used, should be fused... in case they short out.... with a 120 v neon between output side of fuse and neutral... to indicate a blown MOV fuse.

Which MOV's do you use and where do you get them?

### I suppose one could modify the triode board output easily.... and use the 24 vdc control circuitry, to activate/deactivate the INPUT of a opto isolator..... the OUTPUT side of the opto of course, could then be used to activate/deactivate a..'normal' 120/240 vac solenoid coil of a contactor. All that would be needed is an opto with a 24 vdc input, that u sink or source... and a AC output... rated to handle the typ contactor solenoid coil. Most opto's have back emf protection built into the output side.... still I'd use a mov across the AC contactor's solenoid coil.

That's a reasonable solution. Modification is not difficult.

This isn't to minimize the value of a good fuse but to add that a properly functioning circuit can fault the HV supply off so that

all you have to heat the glitch resistor is the stored energy in the capacitor bank. This is precisely what G3/GM3SEK and WD7S do with their boards. That way if you are testing and have one of those "modified" fuses in the circuit, it will still not melt anything down.
### agreed. Stored energy from the caps is pretty wicked with 100-300 uf and a 50 ohm glitch R.[and 7900 vdc no load].. IE: 3100-
9300 JOULES Everything else is just .."follow on energy".. from the plate xfmr/FWB. ### I have seen pix of John Lyles stuff... where they used both an electronic crowbar on the hv B+ to B- [used since pulse rated service like YC-156's..rated for 67 A of plate current means too much V drop across a typ glitch R... hence no glitch R used in any pulse service amp].... and also electronic fault detection circuits where by primary AC is removed. Also seen pix of his HV diode boards.. used in 3 - phase HV pwr supplies... which resemble charcoal.... when the crowbar failed.... and the fault detection also failed... or was not fast enough.

You do all you can and something can still fail but we've gone from jumpering a fuse with copper wire to worrying about the protection circuit failing.

### seems to me the 2 x triode boards wouldn't handle 3-4 A of normal anode current... but might be modified ?

Look at Paul's board... you can set it up with any external shunt for detecting a fault. Use the board to control any kind of contactor you have.

### I just wanted to keep it simple. Any electronic protection would have to be in addition to properly sized HV fuses and primary breakers.

And if your friend had used a correctly sized fuse, it wouldn't have been an issue.

### We use these electronic current sense devices at work for huge HVAC motor loads,compressor's,chiller's, etc.[70 to 120+ kw normal operating load] It was explained to me, they are used since the start up current is wicked on this stuff... as in 3-7 x normal running current. So, instead of a breaker... it's a current sense activated contactor. One of em crapped out last spring.... causing a huge fire in our main 'motor control center'... destroying a panel 8' wide x 7' tall. Incinerated every wire in all 45 x conduits too.. a real mess. Turns out the motor's were ancient. New motor's all have over temp shut downs built into em. New [adjustable] current sensors have redundant copies.. and fail safe modes. ### How do you know that every function on those triodes boards is gonna function when you need it ? You need some kind of "fail safe" on em so if they lose pwr... everything shuts off.... or perhaps two of em.... with say the outputs driving the relay/conatctor... are in series... so if either one failed... it would still shut off the AC primary, etc.

No, you don't know that it will work but if it is used with the fuse you have done what you can to prevent the smoke. I suppose you could put a "test" button on the front panel to trigger the circuit for test but you could carry this too far real easy.

### A fast, CORRECTLY sized HV fuse will work every time. Heck, you could even put 2 x identical HV fuses in series if you wanted. As a side note, I have seen where fellow's are using 2 x 5 kv [5 kv AC...7kv dc] rated Buss sand filled fuses in series.... in lieu of a single 10 kv [10 kv AC...14 kv dc] 10" long HV fuse.... simply cuz they had a ton of 5 kv fuses... and had 10 kv dc HV supplies [for a 3 x 20]

Well, this thread started with your description of a failure caused by your friend using copper wire instead of a real fuse. There is no device you can install that can second guess someone that is going to drop a copper bar in as a fuse. Everything we do is done with the expectation that the original circuitry will be used as designed. Once part of it is defeated, then all bets are off! ;)

### The 2 x triode boards are a good idea .. as long as any one or more functions on em don't crap out. IF you had say a GM3SEK triode board installed on every amp you owned.... I'd have one extra spare board put away... for a 'fast' replacement..if needed. Then fix the bad board at your leisure. Later... Jim VE7RF

Spares are good.

73, Tony W4ZT

73, Tony W4ZT

pentalab wrote:

Gents

My buddy was recycling his old sand filled fuses... by

soldering

a single strand of 26 ga wire across the 5" long fuse.

Fine

so far.
Amp was running fine the other night... the next day... BOTH

HV

fuses were blown open..... and amp was off from the previous night !
A real mystery. He then decided to solder TWO 26 ga wires across each of the old HV fuses. Next step was adding a

small

resistor to one hot leg of 250 cfm fan.. to slow it down a

bit.

[cools the glitch..... which diss 450 w with a dead cxr... 100

w

on ssb]
At that point all hell breaks loose. The paralleled 100 ohm

225

watt wire wound glitch R's looked like u hit both of em with

a

propane torch for 30 mins each.... charcoal !! We know a

HV

to chassis fault occured... may have been a faulty RFC bypass

cap.

The point here is.... by oversizing the HV fuse.... the load is then transfered to the 100 A breaker in the 240 v main 200

A

panel.... which of course didn't blow open...... instead the glitch R's fried themselves... !
You need well over 100 A to open a 100 A panel breaker.
Over sizing a HV fuse is bad enough.... and you guys want to operate with NO hv fuse at all ?? nuts.
BTW... that Dahl A-540 hypersil C core 253 lb plate xfmr I have... has a .01 ohm primary.... and a 6.06 ohm sec [5200 v tap] You got any idea how much current you can suck from

one of

these things ..... LOADS... as my buddy with the same 253 lb

xfmr

just found out. 253 lb xfmr with a core good for 20 KVA CCS with a 100 A slo breaker... vs lowly glitch R [wound

with

nichrome wire no less] .... no contest.... glitch loses every time........ unless a correct sized HV fuse is used !
later... Jim VE7RF

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

### Why don't u take some of that 4 wire home depot 8 awg...

and parallel em into 2 pairs.... eq ga is then 5ga.

RICH SEZ...And throw away the extant 4ga. wire?

#### The above was a joke. IMO ur 100' length [200' loop] of
4 ga wire is WAY too small for a 4x10. 4 ga wire isn't
even rated to handle 110 A.....never mind the 4-6 x that
current.... every 8.3 msecs. Calculate the PEAK current drawn
from the plate xfmr pri on a huge C input HV supply... and you
will see why I use big everything, including wire, contactor's,
etc.... from 200 A main panel to pri of 253 lb Dahl plate
xfmr. Duncan's pwr supply modeler.. PSUD-2 comes in handy for
this stuff. It also has 2 x methods of calculating plate xfmr
pri IMPEDANCE. Z is used to calculate peak pri current drawn...
not simply plate xfmr pri dc resistance.

#### 3/000 CU from main 200A panel to HV supply is what's
really needed. Snip a few strands to make it fit the 100 A
breaker at EACH end.

later... Jim VE7RF

Since I prefer single capacitors as a blocker,
I always use Draloric or Rosenthal caps, they are available at all kind of
capacities and voltages.
The are also very nice caps from Russia on the market with high values of
kvar.
Sometimes I also use mica caps by Jahre which are small and powerful, those
are harder to obtain

73
Peter

________________________________

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

### Me, I just use normal HEC HT-57's.... and HT-59's. I also
have looked at Draloric's and similar HEC block caps... these
ones look like aprx 2000 pf @ 10 kv, 60 A CCS @ 32 mhz....
and are aprx 3-5" diam.

--- In ham_amplifiers@..., Tony King - W4ZT <w4zt-
060920@...> wrote:

Jim,

Don't you think that if a properly designed fault detection

circuit similar to the triode and tetrode boards available today
would have caused a primary circuit shut down saving the glitch
resistors from becoming a smoking pile?

### Partially agreed. Seems to me the 2 x triode boards
available, are based on using an external 24 vdc DPST RELAY...
whose contact's are in the 240 v primary. I don't see any 24
vdc RELAY's... with contacts rated for 100-400A. AC contactor's
on the other hand are all either DPST-DM or TPST-DM.... the "DM"
means 'double make'.... IE: essentially each pole is two sets of
contacts in series.... with an input lug... output lug... and a
huge bar on top that comes crashing down on the input/output.

### The DM arrangement is used [vs a dpst relay] simply cuz a
DM will break the arc into two arcs = essentially zero arc....
[when trying to break a full bore load from a xfmr/motor]

### I never see giant bolt down MOV's across the in/out poles
of any contactor's in commercial service.... but I always install
the big bolt down MOV's across all the poles of my own
contactor's in HV supplies anyway. The MOV's.. if used, should
be fused... in case they short out.... with a 120 v neon between
output side of fuse and neutral... to indicate a blown MOV fuse.

### I suppose one could modify the triode board output
easily.... and use the 24 vdc control circuitry, to
activate/deactivate the INPUT of a opto isolator..... the OUTPUT
side of the opto of course, could then be used to
activate/deactivate a..'normal' 120/240 vac solenoid coil of a
contactor. All that would be needed is an opto with a 24 vdc
input, that u sink or source... and a AC output... rated to handle
the typ contactor solenoid coil. Most opto's have back emf
protection built into the output side.... still I'd use a mov
across the AC contactor's solenoid coil.

This isn't to minimize the value of a good fuse but to add that a
properly functioning circuit can fault the HV supply off so that

all you have to heat the glitch resistor is the stored energy in
the capacitor bank. This is precisely what G3/GM3SEK and WD7S do
with their boards. That way if you are testing and have one of
those "modified" fuses in the circuit, it will still not melt
anything down.

### agreed. Stored energy from the caps is pretty wicked with
100-300 uf and a 50 ohm glitch R.[and 7900 vdc no load].. IE: 3100-
9300 JOULES Everything else is just .."follow on energy".. from
the plate xfmr/FWB.

### I have seen pix of John Lyles stuff... where they used both
an electronic crowbar on the hv B+ to B- [used since pulse
rated service like YC-156's..rated for 67 A of plate current
means too much V drop across a typ glitch R... hence no glitch R
used in any pulse service amp].... and also electronic fault
detection circuits where by primary AC is removed. Also seen
pix of his HV diode boards.. used in 3 - phase HV pwr supplies...
which resemble charcoal.... when the crowbar failed.... and the
fault detection also failed... or was not fast enough.

### seems to me the 2 x triode boards wouldn't handle 3-4 A of
normal anode current... but might be modified ?

### I just wanted to keep it simple. Any electronic protection
would have to be in addition to properly sized HV fuses and
primary breakers.

### We use these electronic current sense devices at work
for huge HVAC motor loads,compressor's,chiller's, etc.[70 to 120+
kw normal operating load] It was explained to me, they are used
since the start up current is wicked on this stuff... as in 3-7
x normal running current. So, instead of a breaker... it's a
current sense activated contactor. One of em crapped out
last spring.... causing a huge fire in our main 'motor control
center'... destroying a panel 8' wide x 7' tall. Incinerated
every wire in all 45 x conduits too.. a real mess. Turns out the
motor's were ancient. New motor's all have over temp shut
downs built into em. New [adjustable] current sensors have
redundant copies.. and fail safe modes.

### How do you know that every function on those triodes boards
is gonna function when you need it ? You need some kind of "fail
safe" on em so if they lose pwr... everything shuts off.... or
perhaps two of em.... with say the outputs driving the
relay/conatctor... are in series... so if either one failed... it
would still shut off the AC primary, etc.

### A fast, CORRECTLY sized HV fuse will work every time.
Heck, you could even put 2 x identical HV fuses in series if
you wanted. As a side note, I have seen where fellow's are using
2 x 5 kv [5 kv AC...7kv dc] rated Buss sand filled fuses in
series.... in lieu of a single 10 kv [10 kv AC...14 kv dc] 10" long
HV fuse.... simply cuz they had a ton of 5 kv fuses... and had 10
kv dc HV supplies [for a 3 x 20]

### The 2 x triode boards are a good idea .. as long as any one
or more functions on em don't crap out. IF you had say a GM3SEK
triode board installed on every amp you owned.... I'd have one
extra spare board put away... for a 'fast' replacement..if
needed. Then fix the bad board at your leisure.

Later... Jim VE7RF

73, Tony W4ZT

pentalab wrote:

Gents

My buddy was recycling his old sand filled fuses... by

soldering

a single strand of 26 ga wire across the 5" long fuse.

Fine

so far.

Amp was running fine the other night... the next day... BOTH

HV

fuses were blown open..... and amp was off from the previous
night !

A real mystery. He then decided to solder TWO 26 ga wires
across each of the old HV fuses. Next step was adding a

small

resistor to one hot leg of 250 cfm fan.. to slow it down a

bit.

[cools the glitch..... which diss 450 w with a dead cxr... 100

w

on ssb]

At that point all hell breaks loose. The paralleled 100 ohm

225

watt wire wound glitch R's looked like u hit both of em with

a

propane torch for 30 mins each.... charcoal !! We know a

HV

to chassis fault occured... may have been a faulty RFC bypass

cap.

The point here is.... by oversizing the HV fuse.... the load is
then transfered to the 100 A breaker in the 240 v main 200

A

panel.... which of course didn't blow open...... instead the
glitch R's fried themselves... !

You need well over 100 A to open a 100 A panel breaker.

Over sizing a HV fuse is bad enough.... and you guys want to
operate with NO hv fuse at all ?? nuts.

BTW... that Dahl A-540 hypersil C core 253 lb plate xfmr I
have... has a .01 ohm primary.... and a 6.06 ohm sec [5200 v
tap] You got any idea how much current you can suck from

one of

these things ..... LOADS... as my buddy with the same 253 lb

xfmr

just found out. 253 lb xfmr with a core good for 20 KVA
CCS with a 100 A slo breaker... vs lowly glitch R [wound

with

nichrome wire no less] .... no contest.... glitch loses every
time........ unless a correct sized HV fuse is used !

later... Jim VE7RF





Yahoo! Groups Links

On Nov 19, 2006, at 2:59 AM, pentalab wrote:

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

...
RICH SEZ.... A 20kV rated C to block 7000V DC sounds like over-

engineering since the actual AC potential across the blocker is
minimal.

#### Rich... Jenning's engineers tell me when using either fixed
glass/ceramic vac cap as a PLATE Blocker.... MIN V rating of the
FIXED vac cap has to be a MINIMUM of 3 X No load plate V......
other wise u get "whisker's" growing on the OFC plates on the
cap..... which will REDUCE the caps V rating.

So why does the statement I quoted in the Jennings catalog on p.4 about DC operation state otherwise?

### Ur gonna get "whisker's" anyway in plate block service for
a fixed vac cap.... so the 20 kv cap... will actually be over
time... a lot lower than 20 kv. IF u Hi-pot test a fixed vac cap
that has been used for plate block service.... u will see it no
longer hi pot tests to 20+ kv any more.

### other than 11m ops... I never see fixed vac caps used as plate
blockers.

I do, Jim. Even 500pF is plenty for a DC blocker at 1.8MHz (XC = 190- ohms) in typical amplifiers since RL is in the kilo-ohms range.

11m ops don't need much C for 11m... 100-250 pf max
is what they typ use. Their requirements are for a plate block cap
that handles LOTS of RF... esp for 4x20's, etc.

Tom Rauch apparently knows a Ham who mistakenly used a 100pF DC blocker in a homebrew amplifier. The amplifier produced the expected output from 1.8 to 28 MHz. Sometime later, when a friend was being shown the amplifier, he noticed that there were only twp zeros after the 1 on the blocker cap. When a 1000pF cap was substituted for the 100pF cap, the output did not increase although the tuning changed slightly on the 1.8MHz band.
...
R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

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

On Nov 18, 2006, at 7:29 AM, pentalab wrote:

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

wrote:

On Nov 18, 2006, at 1:42 AM, pentalab wrote:

### Jenning's told me, IF you are going to use.. say
a FIXED vac cap... as a PLATE BLOCK CAP [don't laff... LOADS

of

11m QRO amps use fixed ceramic/glass vac caps as plate
blockers... mounted vertical... connected with a special

clamp,

to

the center anode typ .82" solid pin] that the vac cap has to

be

DE-RATED by 60% for V. IE: For an amp with say 7 kv no load
HV supply.... use a min of a 20 kv test rated vac cap.

RICH SEZ... A 15kV - tested Tune-C would do the job - provided

that

the DC blocker cap was ahead of the Tune-C. With a 7000V anode
supply, and a g-g triode, the AC anode potential would be c. +/–
6700V-peak. Since the RF rating of a vacuumis 60% of it's DC
rating, or 9000V in this case, a 15kV cap would do the job. -
note - The "Plywood Box" amplifier used a 15kV tested Tune-C and

a

9000V NL anode supply. The Tune C did not arc.

### Rich, when are u gonna read the posts more carefully ???????

RICH SEZ ...Sorry.

We are talking about using a FIXED vac cap.... AS A PLATE
BLOCKER !!!!!!!!!!

RICH SEZ.... A 20kV rated C to block 7000V DC sounds like over-

engineering since the actual AC potential across the blocker is
minimal.

#### Rich... Jenning's engineers tell me when using either fixed
glass/ceramic vac cap as a PLATE Blocker.... MIN V rating of the
FIXED vac cap has to be a MINIMUM of 3 X No load plate V......
other wise u get "whisker's" growing on the OFC plates on the
cap..... which will REDUCE the caps V rating.

### Ur gonna get "whisker's" anyway in plate block service for
a fixed vac cap.... so the 20 kv cap... will actually be over
time... a lot lower than 20 kv. IF u Hi-pot test a fixed vac cap
that has been used for plate block service.... u will see it no
longer hi pot tests to 20+ kv any more.

### other than 11m ops... I never see fixed vac caps used as plate
blockers. 11m ops don't need much C for 11m... 100-250 pf max
is what they typ use. Their requirements are for a plate block cap
that handles LOTS of RF... esp for 4x20's, etc.

Later... Jim VE7RF

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

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

Jim,

Do you think there is any difference in the voltage capacity of

fixed or variable vacuums caps by Jennings specified for the SAME
DC voltage?

73
Peter

### No.

### The point Jennings was making...was IF using a fixed vac cap
as as DC BLOCKING cap.... the vac cap will have HV DC on one side
of it all the time.... and the vac cap will "grow whiskers" on
it's OFC copper plates.... leading to v break down. That's why
Jenning's sez to size the vac cap to a min of 3 x normal no
load plate V.

### Me, I just use normal HEC HT-57's.... and HT-59's. I also
have looked at Draloric's and similar HEC block caps... these
ones look like aprx 2000 pf @ 10 kv, 60 A CCS @ 32 mhz....
and are aprx 3-5" diam.

### Why 11m ops want to use fixed glass/ceramic vac caps for
plate block caps is beyond me. They would handle bags of RF
current though. Probably for big amps. However... 8 x 200 pf HT-
57's will handle 104 A. 4 x 500 pf HT-59's will handle 92 A.

later... Jim VE7RF

________________________________

From: ham_amplifiers@...

[mailto:ham_amplifiers@...]

On Behalf Of pentalab

RICH SEZ... A 15kV - tested Tune-C would do the job - provided

that

the DC blocker cap was ahead of the Tune-C. With a 7000V anode
supply, and a g-g triode, the AC anode potential would be c. +/-
6700V-peak. Since the RF rating of a vacuumis 60% of it's DC
rating, or 9000V in this case, a 15kV cap would do the job. -
note - The "Plywood Box" amplifier used a 15kV tested Tune-C and a
9000V NL anode supply. The Tune C did not arc.

### Rich, when are u gonna read the posts more carefully ???????
We are talking about using a FIXED vac cap.... AS A PLATE
BLOCKER !!!!!!!!!!

Hal I don't take everything back.

We've been talking residential services here not commercial.

The actual current ampacity for 2/0 copper is 190 amps but it is allowed to
be fused to 200 for Residential Service Feeds only in many cities.

2/0 copper is acceptable in way over 1/2 of the cities in the country for
feeding a 200 amp RESIDENTIAL SERVICE. In the other half they require 3/0.
You must check your locality when pulling a 200 amp service. They operate
in the 5% grey area.

3/0 copper is required in commercial services.

Sioux Falls, SD is one of those towns where 2/0 copper is acceptable for
service feeds. Minneapolis where I worked as an electrician in the mid 80's
was another. Do not confuse COMMERCIAL SERVICES with Residential
Services...

It's like comparing Apples and Oranges can't be done.

So what do we have here? We have the NEC and most cities are dead locked on
the code by legislation. Others fly by the seat of their pants in other
areas.

What I don't like is here while we can pull 2/0 when we change out a service
we are required by city ordinance to UPDATE our houses to the current code
everywhere else. This means ARC FAULT circuits in the bedrooms (which I
haven't done yet) and Ground Fault breakers or outlets in the kitchens,
laundry and bathrooms.


This house of mine was built in 1962 with a 60 amp service. Many of the
rooms just had barely 2 outlets. Fortunately the past owner updated to a 20
circuit 100 A panel in 1972 and added the required circuits in the kitchen
and baths.

The first thing I did, like the first week was rehung a new 30 circuit 100
amp panel so I could even hook up some radio without blinking every light in
the place.

I've since installed a 200 Amp service panel with 40 circuits (5 - 30 amp
220's to the radio room, plus a 30 amp 120 that feeds the 24 outlets in the
radio console)

The basement is wired to the max all the way to code and broken up nicely.
I think I have 4-5 circuits left in that panel.

The garage has a 100 Amp sub panel with the hot tub 50 ground fault sub
panel off of it, the RV 50 amp ground fault circuit, lighting, garage power,
a 30 amp garage 220 incase I need to test an amp or something, 2 - 20 amp
each side of the garage door block heater plugins for the diesel truck,
etc.. All ground fault where outlets are, plus a panel outlet.

OH yeah, the Meter Sequence here needs to be a METER MAIN, where the actual
main breakers are in the meter box. This is because it is 20 feet through
an addition before my main panel in the basement.

That meter main has room for 8 - 220 breakers.

I figure I will light up the yard from there TIM ALLEN with his Christmas
Lights.

If I ever do build that 30 x 40 garage I will probably put in a 400 amp
panel out there and sub feed the house. That 200 Amp service is pretty
busy.

Convenience is nice, but if I cranked up everything here I would have to
call the POWER COMPANY and tell them to pull the BORON RODS out of the
reactor another inch...

BOB DD

Subject: RE: [ham_amplifiers] Re: AC Breaker panels... sub panels...
Electrical codes, etc.

The power company is the other side of the world.
I take everything I say back. I'm understanding what you have setup
better understood. I had the same thing at my farm.
Is the Disconnect on the pole fused or just a disconnect? The wire
going to the house and garage/barn are just fine. The disconnect has
400amp fuses , I could change to 200amp fuses , I would have to have the
heat on in the house , the stove cooking and strike up the welder in the
barn to over load 200amp fuses
The power feeding your house is just power company (even if you supplied
it) wiring. This is just fine as long at it doesn't go more than 5
feet inside your house before hitting the breakers. It doesn't need to
be fused as it is service wiring. It comes right up into the 200amp
breaker , less than 5 feet inside

Sorry for blasting off the first post. It was the first thing I did
this AM, got up at 10:15. I have a Bar schedule. No problem , thanks
for the help.

BOB DD

_____

From: ham_amplifiers@...
[mailto:ham_amplifiers@...] On Behalf Of Rich & DJ
Sent: Saturday, November 18, 2006 4:42 PM
To: ham_amplifiers@...
Subject: RE: [ham_amplifiers] Re: AC Breaker panels... sub panels...
Electrical codes, etc.

Well I guess all is not good because the wire running to the house and
the wire running to the shed are alum for 200 amp service each. I can
see it in the disconnect where it is dual 200amp lines, then it goes
underground , the conduit divides somewhere underground an feeds the two
200amp breaker boxes. The pole has a 380A commercial, 400A residential
transformer.
If I need heaver wire to my breakers then why do people in a subdivision
not need a wire rated for the transformer on the pole?
This had to be in place when it was first done because it can't be
turned off at the meter. If you pull my meter, all is still hot. My
meter runs off a current transformer. Just curious, not trying to
question your statement, just trying to lean.

Size 3/0 AWG wire is the correct guage to use for 200 ampere service,
not 2/0 AWG.

In any circumstance the wire diameter needs to be sized to the
breaker protecting it.

In a dead short situation you will want the breaker opening, even if
it is rated at 125 to 150 percent tripping, well before the wire
heats up to the point where the insulation melts and possibly catches
fire or releases poisonous gases.

The only point where the a.c. electrical ground is bonded to the
neutral should be in the main distribution panel and not in any sub
panel or appliance.

In commercial 200 amp single-phase, three wire installations the size
of the a.c.e.g. is 2AWG while the current-carrying conductors are 3/0
AWG. This is because the a.c.e.g. is a fault drain and not a current-
carrying conductor, but in D.C., everything changes, and that is a
topic for a separate discussion.

Lastly, in amateur appliances such as medium power transmitting
equipment, the connection to the frame of the equipment, e.g., the
frame ground or RF static drain, should be of the heaviest guage
affordable, and this conductor needs to be bonded to all the other
a.c.e.g and static grounds, ground rods, external ground ring,
interior halo, etc.

Hal Mandel
W4HBM