Am 24.09.2006 um 09:52 schrieb pentalab:

### Millens are fine up to 5 kv. For the 5-10 kv stuff....
I'm going to go to a better connector.

Which ones would these be?

I have found Huber+Suhner (Switzerland) but their SHV type connector is rated at 3.5 kV rms / 5 kV DC only.

hs-p-rf-con-gr/hs-p-rf-con-gr-series/hs-p-rf-con-gr-series-shv.htm

73, Frank DG1SBG

Am 24.09.2006 um 09:38 schrieb pentalab:

--- In ham_amplifiers@..., Frank Goenninger <frgo@...>
wrote:

### I'm going to attempt to post some pix in the photo area..
IF I can figure it out. I'm no PC geek. Worse comes....
I'll e-mail some to u direct.

Jim

Thanks, Jim! If you want me to post them in this group at yahoo please let me know!

Meanwhile I was able to find a movie on WWW showing you in the shack with some pictures of homebrew stuff. I especially love that photo with the cat. Hi-Hi!

73, Frank

--- In ham_amplifiers@..., "Mike Sawyer" <w3slk@...>
wrote:

Let me correct this:



Jim said: This is my "external cap box". I used Millen Red/ Black

HV

connector's on it. IF using the Millen's.... either use
nylon mounting screws or mount em on Micarta. Both Kings and
ROWE make better HV connector's imo.

Where can one find the Kings or Rowe connectors?

#### Try a google on kings or rowe. SSON has some.... so
does Jerry Thompson at Economy electronics... in Loanoke Ark.
He has a website too. ..think it's Economyelectronics.com



The only thing I have in my junk box are the Millen Red and the
brown phenolic. I understand the brown ones *aren't* very good.

## They are not. Only use the red/black ones.


However, my local parts jobber confided in me that the Millen
connectors were supposedly rated for 4500 VDC.

### Millen rates em at 7 kv. U HAVE to mount em from the
inside to use em at high V. Mount em on the outside.... and
I had one arc to the chassis once... and another arc to the
machine screw holding the millen down.

## Trbl with mounting em on the inside is... with 1/8" thick
panels I use... the mating screw on connector will butt up
against the panel 1st.

## If u mounted em on insulating material... they would never
arc.

### If the RF deck/HV supply is all in one box.... don't mess
with connectors... just hardwire everything with sta-kons
[solder em, as well as crimp em] on each end.. and heat shrink.

### Millens are fine up to 5 kv. For the 5-10 kv stuff....
I'm going to go to a better connector.

Later..........Jim VE7RF

Mod-U-Lator,
Mike(y)
W3SLK

--- In ham_amplifiers@..., Frank Goenninger <frgo@...>
wrote:

Am 23.09.2006 um 15:41 schrieb pentalab:

I couldn't resist.

I'm dying to see some beautiful pictures of all those neat things

you

describe... Please be so kind and put some into the photos area

of

this group on yahoo.

Mni tnx de Frank DG1SBG

### I'm going to attempt to post some pix in the photo area..
IF I can figure it out. I'm no PC geek. Worse comes....
I'll e-mail some to u direct.

Jim

--- In ham_amplifiers@..., "Paul Christensen"
<pchristensen@...> wrote:

The boys on the contest reflector finally figured out the same

thing. The typ W2DU baluns using 303 teflon coax.. and the
tiny type 75 beads would heat up with just a 500 w dead cxr on
all bands from 1.8 to 30 mhz. They switched to type 43
small beads... and the same small 303 teflon coax.[slightly
longer.. more beads] They ran the exact same test as b4.....
except 2200 watts.... zero heat ! ..."

Jim, I like air wound baluns best. But as you point out, the

geometries can oftentimes get in the way. In the alternative, I
have successfully used a combination of #43 and #77 material on RG-
214. The #43 material is used on the ends with #77 beads sandwiched
in between over a distance of ~ 60 inches. That can create some
weight and manipulation problems too. In that case, it's tough to
beat the W1JR or W2FMI technique of winding RG-303 (at 1.5KW level)
onto large #31 mix cores. I believe the DX-Engineering baluns are
constructed this way.

Paul, W9AC

#### Tnx Paul. The W1JR baluns on Array Solutions site are
rated at 5 kw....... which is the rating of 303 @ 10 mhz !

### Z goes up to the square of the turns. Of course...
winding 393 on a torroid is impossible...... hence sliding beads
over 393.

### Some have experimented with type 43 beads at the ant end....
followed by type 77. It's the beads closest to the ant feedpoint
that are gonna heat up.

### The weight/bulk/windload of solenoid coax wound baluns is
a
real pig. I'd never do it again.

Later.....Jim VE7RF

开云体育

On Sep 23, 2006, at 3:31 PM, Tony King - W4ZT wrote:

R L Measures wrote:
<snip>

Lifting an 85lb transformer is not easy for this old fart.

A small fold up Engine Lift can solve that and many other heavy lifting
jobs. One of these helped me lift my mill and lathe when I brought them
home and I have a 164 lb Peter Dahl to move too ;)

I used a sledge hammer handle, a strap, a hook, helper-girl on one end of the handle, and me on the other end to lift it in place.

73, Tony W4ZT




Yahoo! Groups Links

R L MEASURES, AG6K. 805-386-3734
r@...

R L Measures wrote:
<snip>

Lifting an 85lb transformer is not easy for this old fart.

A small fold up Engine Lift can solve that and many other heavy lifting jobs. One of these helped me lift my mill and lathe when I brought them home and I have a 164 lb Peter Dahl to move too ;)

73, Tony W4ZT

Dick,

You can buy a 1-2 ton chain fall hoist from harbor Freight for about
$40.00. One can mount this in the ceiling stationary by the hook, and
pull a pick up truck under it allowing the lift (if the ceiling is
high enough). It takes about the same amount of room as a come-a-long,
but is way easier to use. One can build some dollys to set the
equipment on and move it around the shop where ever you want.
Actually, One could mount the hoist outside to get it higher in the
air for a larger truck if you have a hard top or corcrete drive way to
roll the dolly on. They also make a set of wheels that riggers use to
move heavy machinery the same way. You can sometimes find them on ebay
at a cheap price.

If I was to use a hoist of any kind, I'd strongly recommend obtaining
a small I beam about 8 inches high at least, and set it atop two walls
to carry the load. Then mount the hoist to it. You can run these
between ceiling joists and set the ends on top of the sill plate. A
lot of the time, you can buy one cut new pretty cheap. A scrap yard is
another place to look. You only need one about the size that some
place over double-car garage doors in place of a header when they use
brick.

A luxury is to get is a small fork lift if you have a garage. Here,
they come in at the local two scrap yards all the time. To be honest,
there's not much wrong with some. A buddy of mine who owns a small
machine shop bought one from one of the yards that was electric and
they threw in a charger. I rebuilt the drive board and got it going. I
think he got it for $0.08 a pound which was $0.02 over what they paid.
I think it was one by Yale, however it was white in color. They are
very nice if your going to be doing a lot of heavy lifting. You can
mount a boom on the forks and you have a built in crane. I ran my
welding/repair portion of my machine shop with two lift trucks this
way.

Best,

Will



--- In ham_amplifiers@..., PA3DUV <pa3duv@...> wrote:

Lifting an 85lb transformer is not easy for this old fart.

I just put an M24 2 metric tonne lifting eye on a 1ft studbolt

through the steel reinforced concrete ceiling of my garage to get the
30 kVA 1500 rpm diesel genset and HT power supply on and off the
trailer. Using a chain come along even a physically challenged person
like the undersigned can do the job ;-)

Cheers, Dick
PA3DUV



----- Original Message -----
From: R L Measures
To: ham_amplifiers@...
Sent: Saturday, September 23, 2006 1:37 PM
Subject: Re: [ham_amplifiers] Re: HIGH SWR / HIGH REFLECTED POWER

SHUT DOWN CIRCUIT !!

On Sep 23, 2006, at 1:35 AM, pentalab wrote:

> --- In ham_amplifiers@..., PA3DUV <pa3duv@> wrote:
>>
>> Great info Jim!
>> NOW we're talking amplifiers ;-)
>>
>> This yahoo group has the possibility of posting pictures, files

and

> the like. Some pics of your "QRP" amps (They also make the usual

10

> kw 5 kw.. 2.5 kw qrp slugs.) would be very much appreciated.
>>
>> Thanks again for the very interesting contributions!
>>
>> Cheers, Dick
>> PA3DUV
>
> ### Tnx Dick..... As soon as I can figure out this pix posting
> deal... We will try and get some pix up.
>
> ### Just to set the record straight. I design this QRO stuff
> [including everything downstream like baluns, LC networks for
> stacked arrays, etc, for ... "clients" [who will remain
> nameless for obvious reasons]
>
> ### IMO.... I could care less how one gets their ERP. 1500w
> into stacked yagi's is... "OK".... but 5 kw into a dipole is
> a "no-no" ..gimme a break !
>
> ### These 1500-2000w amps just bore me to tears. IMO... it's
> just as easy to build a big one as a small one.

Lifting an 85lb transformer is not easy for this old fart.

> To me, it's an
> engineering challenge.

Indeed.

> ... since you will never read any... "how to
> build a 5-15 kw linear" in any ARRL hand book / QST article.

The laugher is that W1AW had an Alpha 2, 8877 amplifier until the
ARRL sold it to because it had a habit of zapping 8877s. The
purchaser of the amplifier, QST Editor Mark Wilson, installed a

low

VHF-Q parasitic suppressors and apparently put the amplifier to

good

use.
>
> ### When AES / RF Parts / Coaxial Dynamics tell me they
> sell 10 kw slugs like popcorn.... it's blatantly obvious this
> QRO scenario is, and always has been.. alive and well.
>
> ### Eimac tells me their is this... "secret world wide
> underground network of QRO amp bulders ".... so secret.. they
> don't even know each other !!
>
> ### For a laff... check out JA6TAY's site. He doesn't mess

about.

>
>
> ### Well, the cat's out of the bag now ! I fully intend to post
> as much of these "trade secrets" as I can. None of it is
> rocket science really.

Amen to that.

> It starts off as an engineering
> problem... reverts to a... "sizing issue" then back to an
> engineering issue.
>
> ### All as it amounts to is ... either using bigger
> components.... or doing stuff like paralleling 8 x 200pf @ 15
> kv HEC ceramic doorknobs to make a plate block cap assy.

With one or two thousand ohms of of RL, 1600pF is not necessary

for

the DC blocker cap at MF/HF.
>
...

cheers, Jim

R L MEASURES, AG6K. 805-386-3734
r@...

开云体育

开云体育

开云体育

开云体育

Am 23.09.2006 um 15:41 schrieb pentalab:

I couldn't resist.

I'm dying to see some beautiful pictures of all those neat things you describe... Please be so kind and put some into the photos area of this group on yahoo.

Mni tnx de Frank DG1SBG

开云体育

I couldn't resist.

To make a 40-10m choke balun for 40-10m yagi's use type 43
beads [1" OD x .5" ID x 1" long] slid over RG-393 teflon
coax. The balun is 17" long when completed [16-17 beads.]

The Z at 7 mhz is 1350 ohms. On 10/12m... power rating is
8500 watts CCS dead cxr.

For 75m it has to be 24" long [1350 ohms Z.]

For 160m, it has to be 30" long [1350 ohms Z]

And no... 500 ohms Z is NOT enough... take ur ARRL ant
book ...and toss it !

10 turns of 10" diam 213 u won't work on 75m either.... too
low a Z. Coiled up coax in a solenoid is a huge windload...
and a pain to manhandle on a tower. When using [expensive new]
393 teflon high power coax... the last thing u need is a megabuck
worth of coax to make a solenoid.

Besides.. a real linear will cook 213 u on 75m.

Type 43 is bomb proof... and cheaper than the type 77 beads
[type 77 is shorter .81" long]

Type 43 beads are still $2.00 each.... the inferior type 77
are $3.00 each. They are cheaper still... in bulk from Amidon.

You can also get em pre-made from Ken Hirschberg at Cal-Av
labs..[and also from Jay Terleski at Array Solutions].. comes
with a 7-16 DIN... and teflon coated 10 ga wires. His are
pumped with silicone glop... under pressure.. then bubbles
removed in a vac chamber. All siver soldered to boot. The
teflon wires are unique. Each layer of fine wires is reversed
in twist cw.. ccw...cw...ccw etc.

End result is... when u form the 10 ga wire.. it stays put !!
Won't spring back....slick.

You can't blow these babies up if you tried. They won't heat up
either. Best Balun ever made... period. You can pump 15
kw into em all day long.

The boys on the contest reflector finally figured out the same
thing. The typ W2DU baluns using 303 teflon coax.. and the
tiny type 75 beads would heat up with just a 500 w dead cxr on
all bands from 1.8 to 30 mhz. They switched to type 43
small beads... and the same small 303 teflon coax.[slightly
longer.. more beads] They ran the exact same test as b4.....
except 2200 watts.... zero heat !

I use type 43 for all my bifilar rods as well. [for fils of
thoriated tungsten fils] .. but that will be another story.

Later.... Jim VE7RF

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

On Sep 23, 2006, at 1:35 AM, pentalab wrote:

### These 1500-2000w amps just bore me to tears. IMO...

it's just as easy to build a big one as a small one.

Lifting an 85lb transformer is not easy for this old fart.

##### Use a cum-a-long hooked to a basement beam... or one of
those small devices used to lift small engines. Me... after
tearing the crate apart.... I slid the 253 lb Dahl straight
across from the pallet it came on, to the new RE-enforced
cabinet. I re-enforced it with a sheet of 1/4" aluminium on
top... and unistrut below...used 4.25" dolley wheels.

### Rich.... get some help....from ur helper babe... or ask Riley
H to give u a hand, the next time he stops by... for tea.

.

... since you will never read any... "how to
build a 5-15 kw linear" in any ARRL hand book / QST article.

The laugher is that W1AW had an Alpha 2, 8877 amplifier until the
ARRL sold it to because it had a habit of zapping 8877s. The
purchaser of the amplifier, QST Editor Mark Wilson, installed a

low VHF-Q parasitic suppressors and apparently put the amplifier
to good use.

### Kilobuck 8877's are about the least cost effective.. throw
away tube one can buy these days. You can buy a 3CX-3000A7 brand
new... with a 3 yr - 12,000 warranty for a paltry $50.00
more... and have it rebuilt over and over and over. Instant on
too... and does an easy 5300 watts out... with 200 w of
drive.... or for you legal limit types.... 50 w of drive will
produce 1500 w out.

### Ted Henry agreed with me... said the 8877 for HF... was a
dumb way to go...... unless available as MRI pulls.. or u got
deep pockets. Can you imagine spending 2 grand to re-tube a
2 x 8877 Alpha 77-SX ???

### Alpha's newest amp is gonna use a single 8877... no vac tune
cap... and no pin diodes ! They just don't ..'get it'

### You can buy 2 x brand new YC-243's for a tiny bit more..
[socketless version of a 6000A7 GG triode] For $2200.00 you
can get a brand new Svetlana 3CX-10K

### All as it amounts to is ... either using bigger
components.... or doing stuff like paralleling 8 x 200pf @

15 kv HEC ceramic doorknobs to make a plate block cap assy.

With one or two thousand ohms of of RL, 1600pF is not necessary

for the DC blocker cap at MF/HF.

### I have heard everything from way more [9000 pf] to
slightly less. I can't find any two engineering books that are
evenly remotely close.

### I figured for 1.8 mhz... 1600pf would do the trick. For the
high bands, the caps current rating goes way up.... thank god...
cuz the current through those caps on the high bands is just
bizzare.

#### How much do you think is needed... for say a 1500 ohm
RL @ 1.8 mhz ????

Later...... Jim VE7RF

...

cheers, Jim

R L MEASURES, AG6K. 805-386-3734
r@...

If any of you intend to series parallel Oil caps for greater
V ratings... BEWARE. I did just that with 4 x 50 uf @ 4500 V
units. These were each 12" tall x 8' wide x 4" thick. I
got em years ago from W6RR, Roger Mace... now sk.

I had one of em flash over [6900 vdc no load] . The arc
occured between the steel case and the threaded rod that
comes up outa the oil !! Even though these units had large cone
HV insulator's out the top... the weak spot is BELOW the
insulator /rubber O ring.

The fix was to FLOAT all 4 of em... both from the chassis...
and from EACH other ! I used a huge sheet of 1/4" thick HV
Red Micarta under them... and 1/8" thick sheets of micarta
BETWEEN em. End of problem. Even though mine.. and most of
these oil caps have a nice grnd lug welded to the steel case...
DON'T BOND it to the chassis. By floating all the cases... you
will RELIEVE the stress on em... they will never arc. Treat em
like lytics.

There is now an abundance of huge size 350 V / 450 V / 500V
lytics on the surplus market. 1600uf to 5200 uf. Lotsa
joules ... which is what we want.

The 1600 uf @ 450 V lytics I obtained from Fair radio yrs ago
[$5.00 each] were all measured between 1900 uf and 2000
uf. They were all 3" diam x 6" long... and used # 10 machine
screw terminals.

I mounted 20 of em horizontally [4 rows of 5].... between two
huge sheets of 3/8" thick UHMW [from the local plastic
shop] We used a 3" hole saw in a modified drill press... and
drilled out both sheets at same time.

It all fits in a nice 19" wide short rack... with front and
rear panels. The HV meter is a 0-1 ma with 10 x 2 watt, 1
meg, 2% tol series resistor's.

This is my "external cap box". I used Millen Red/ Black HV
connector's on it. IF using the Millen's.... either use
nylon mounting screws or mount em on Micarta. Both Kings and
ROWE make better HV connector's imo.

Measured C is 100 uf. I built it years ago and used 50 k,
5% tol, 25 watt wire wound's across each cap. If you build
one of these huge lytic stacks... use Rich Measure's 100 K @ 3
watt units across each lytic. For faster bleed down time...
use a PAIR of his 100K 3 watt units across EACH lytic.
With the wirewounds, I used 'L' shaped copper straps on each
screw terminal... to dissipate heat. One end of the 'L' goes
to the screw... the wire wound is screwed to the other end of
the 'L'.

With just a single 50 K resistor across each one.... HV bleeds
down slowly.. a few mins. With 100 K units.... it takes
longer.

I recently obtained cases of 2500 uf @ 450 V lytics from that
fellow in Florida. Now these newer design caps are slick...
only 2" diam x 4" long.... and a whopping 9.8 A CCS ripple
current rating. ESR is aprx 50 MILLI ohms each.

I have 72 of em.... so I'm building 3 x banks .. with 24
caps per bank. I can use 1 or 2 or all 3 banks in parallel.

To protect all this mess.... we used a BUSS HVU-3 HV sand
filled fuse [ SSON has ton's of em... so does Buss... Buss
has em in a huge variety of ratings]. These units are 13/16"
diam on the ends... and fit a standard 3/4" fuse clip snugly.
I used the 3/4" from SSON that have end retainers on em... so
once inserted, there is NO way they can migrate out.. esp when
mounted vertically.

The surplus HV fuses from SSON are rated at 3 A CCS.. and
are sandfilled. $3.50 each... in bulk. The SSON units are
glass bodied.... the newer ones from Buss are Ceramic bodied...
other wise, they are identical. The 5" long HV fuses are
rated at 5 kv AC RMS.... and work at 8 kv DC no sweat.
They also make 10" long fuses... rated at 10 kv AC RMS / 16 kv
DC.

I install ONE of these HV fuses... in ONE leg.... between the
SECONDARY of the Dahl plate xfmr and the FWB diodes. The
2nd HV fuse goes BETWEEN the B+ output of the lytics and the
HV "Glitch Resistor's"

If something ever shorts out in the lytic banks.. the 1st
HV fuse between sec of plate xfmr and HV diodes will save
the diodes every time. With fault current... they blow
REALLY fast.

The 2nd HV fuse, located in the B+ line is always located
BEFORE the glitch Resistor... never after. IF u flipped em
around... and something happened to the glitch R [arc, dust,
etc] the fault current from the lytics could easily damage /
finish off the glitch R assy.



The "Glitch Resistor" for 2.5 to 3.0 A of dc plate
current can be built a couple of ways. My buddy used 2 x
paralleled 100 ohm @ 225 watt wire wound resistor's. A fan is
used on em to keep things cool at all times. With 3 A
keydown... diss is a whopping 450 watts ! On ssb/ cw... it's
only 1/4 of that... or 112 watts. [66 watts per resistor]

The 2nd method employed uses 4 x 200 ohm 275 watt globars...
each 1" diam x 12" long. I had loads of these older, 60's
vintage globars.... TYPE CX. BEWARE, the older CX type
globars are NOT glass bodied.. and are NOT suitable for oil
immersion. Since I couldn't use em for a QRO dummy load... they
make perfect... "glitch resistor's ".

On my buddy's latest project [I designed it, he built it],
while ironing out some bugs... One or both HV fuses opened up a
few times. The paralled 100 ohm-225 watt wirewound's didn't
flinch. The surge current is limited to aprx 158 A..... which
will blow a 3 A rated fuse in <2 msecs. The glitch R and
the C filter will also form a 'RC' time constant. Without a
glitch R... the current from the bank(s) of caps is HUGE...
only limited by the ESR of the 20-30 lytics... and the ESR of
the plate choke(s) 1.25 ohms + 1.2 ohms.


I always use 6A1O diodes... rated at 6 A CCS @ 1 kv PIV...
400 A surge. These babies are exactly double the diam of a
1N5408. They will drop right in where a 1N5408 once stood.
Dahl figured this one out too... and makes all his diode
assy's from 6A1O's. I looked at HV diodes at 8-10-12 A
ratings.... and all of em had LESS surge capability than a
6A10... and all of em required a heatsink.

The 6A1O's are used every where.... from meter protection to
series strings of em... used for BIAS. [tapped with a 20 x
position rotary switch....slickest thing yet]

Don't mess with .01uf disc caps and resistor's across each
diode... waste of time/ money /effort/SPACE. The "IN" way of
building strings of HV diodes is to use ... no load plate
voltage x 3. IOW... for a 7900 V supply... use 24 diodes
per EACH of the 4 legs in a FWB.

Now both Dahl and other's use the "ultimate" in diode
protection. They parallel a 510 v MOV across each diode.
[510LA40A.. available from Mouser, Digi-Key] I also use a 275
V bolt down MOV across the plate xfmr PRIMARY [Movistar,
available from Dahl]... and 130 V bolt down MOV's ... between
each hot leg and neutral/grnd. [available from Mouser/Digi-key]

Some will even install 6 x 1000 v [in series] MOV's across the
plate xfmr sec.

IMO... the huge banks of lytics will "swallow" any
transients, spikes,surges, that manage to get through all of
that. The lytics will look like a low Z short to any higher
V spikes, etc.

Of course... this mess of lytics has to be step started...
properly. We use a 0-30 delay timer.... the type that comes
in a 8 pin octal base... and use the mating flange mount
socket [no holes required for the mating socket... you can
flush mount em to anything] These delay units all use a DPDT
mech relay with 10 A CCS contacts. I get mine with a 120
vac coil. One 1/2 of the DPDT contacts activate the step
start contactor. You can use the other 1/2 of the DPDT
contacts to turn on a NEON.... or close the key line to the
linear..[via a pair of RCA connector's.] This way... the big
amp can't be keyed UNTIL the step start cycle has been
completed. On our step start contactor's that use 220/240v
windings.... both halves of the DPDT relay inside the delay unit
must be used. Fortunately.... those contactor's had AUX
contacts... and the AUX contacts can easily be used to close
the key line to the big amp + turn ON a neon.

The Neon can be used as a visual to let one know that the step
start conatctor /TD relay has operated.

We use 2 x paralled 50 ohm 100 W resistors for the step
start resistor assy. They can be either metal finned bolt
down units... OR wire wounds. If one ever opened up.... the 2nd
one is the back up. If a single resistor was used... and opened
up.... you could shunt a wide open !

The step start assy [25 ohms] is inserted in ONE LEG only of
the primary of the plate xfmr. 50 ohms is too much
resistance... and will produce a bigger current surge when
shunted. Install a 0-50 A AC ammeter or a 0-100A in one leg of
the 240 V primary.... you will get an eye opener ! The 50 A
and bigger AC ammeter's use current xfmr's.... which simply go
around one of the big 120 v hot conductor's. Small 18 ga
wire is then used between the actual meter movement...and the
current xfmr.

Now here's the kicker. Joules [watt seconds] goes up to the
SQUARE of the voltage! When a 8 kv pwr supply is charged up to
4 kv... the caps are only ONE QUARTER charged.. and have 1/4 the
energy of a fully charged cap. The same caps charged up to
5656 volts is only ONE HALF charged up !!

The trick here is to get the HV up as HIGH as you can... BEFORE
shunting out the step start resistor. This implies NOT
sucking huge amounts of bleeder current. Also BEWARE... all
these Dahl / Pole pig plate xfmr's typ suck 1.4 to 1.8
Amps of ac magnetizing current on their 240 v primaries.....
even with NOTHING connected to the HV secondary !! [The
magnetizing current will always be flowing through the step
start resistor... until it's shunted] .

We typ set the TD delay for 14-20 seconds... with 'typ' 100-135
uf C input HV supplies. And longer with 200-300 uf supplies.

34 uf will typ give you aprx 3% ripple. [6900 V @ 3 A]
100 uf will give you 1 % ripple. Ripple is one thing....
dynamic regulation is another [as opposed to static
regulation] . To get good dynamic regulation on a FWB C input
HV supply.... you want to shoot for 1% or less ripple.

These Dahl 253 lb xfmr's I use have a .08 dc ohm primary...
and a 8.2 dc ohm secondary ! My 10 kva Hypersil pole pigs typ
have 16-18 ohms of sec dc resistance.

Dahl tells me there is NO problem whatsoever using 150-300 uf
C input filters with his xfmr's.

If modifying a 3 pole contactor as one big SPST-DM contactor...
after paralleling the 3 contacts on each side.... you go in on one
corner... and exit diagonally. [enter top left... exit bottom
right] This will distribute the current evenly. This trick
is also used on paralled doorknobs, diodes, bandswitch wafers,
breakers, broadcast caps, etc.

On these latest bunch of 135 A rated 3 pole contactors... we
paralled all 3 poles with just aluminium 1" x 1" x 1/8"
thick 6061-T6 angle stock. This also makes it EASY to
terminate the 2 ga wire used [and also 3 x ought] Also makes
it easy to simply bolt two angles together... when the output
of one contactor is feeding the input of the step start
contactor. One modified contactor is installed in each hot
leg. The 135 A rating looked a little flaky to me... and we had
plenty of contactor's... so instead of 2... we used 3 x modified
ones. I also would suggest silver plating the contacts
with 'cool amp'... available from the cool-amp co... in Ore. I
use that stuff to silver plate everything from contacts to
tank coils to loads of copper strap. Use latex/vinal gloves..
and use ur fingers to rub it in. Contact resistance will drop
to zero every time. It works EXTREMELY well... so does 'conducto
lube'... used on sliding contacts.... pure silver in grease.

Sri for the diatribe. Sorry for boring anybody.

Later... Jim VE7RF

On Sep 23, 2006, at 1:35 AM, pentalab wrote:

--- In ham_amplifiers@..., PA3DUV <pa3duv@...> wrote:

Great info Jim!
NOW we're talking amplifiers ;-)

This yahoo group has the possibility of posting pictures, files and

the like. Some pics of your "QRP" amps (They also make the usual 10
kw 5 kw.. 2.5 kw qrp slugs.) would be very much appreciated.

Thanks again for the very interesting contributions!

Cheers, Dick
PA3DUV

### Tnx Dick..... As soon as I can figure out this pix posting
deal... We will try and get some pix up.

### Just to set the record straight. I design this QRO stuff
[including everything downstream like baluns, LC networks for
stacked arrays, etc, for ... "clients" [who will remain
nameless for obvious reasons]

### IMO.... I could care less how one gets their ERP. 1500w
into stacked yagi's is... "OK".... but 5 kw into a dipole is
a "no-no" ..gimme a break !

### These 1500-2000w amps just bore me to tears. IMO... it's
just as easy to build a big one as a small one.

Lifting an 85lb transformer is not easy for this old fart.

To me, it's an
engineering challenge.

Indeed.

... since you will never read any... "how to
build a 5-15 kw linear" in any ARRL hand book / QST article.

The laugher is that W1AW had an Alpha 2, 8877 amplifier until the ARRL sold it to because it had a habit of zapping 8877s. The purchaser of the amplifier, QST Editor Mark Wilson, installed a low VHF-Q parasitic suppressors and apparently put the amplifier to good use.

### When AES / RF Parts / Coaxial Dynamics tell me they
sell 10 kw slugs like popcorn.... it's blatantly obvious this
QRO scenario is, and always has been.. alive and well.

### Eimac tells me their is this... "secret world wide
underground network of QRO amp bulders ".... so secret.. they
don't even know each other !!

### For a laff... check out JA6TAY's site. He doesn't mess about.


### Well, the cat's out of the bag now ! I fully intend to post
as much of these "trade secrets" as I can. None of it is
rocket science really.

Amen to that.

It starts off as an engineering
problem... reverts to a... "sizing issue" then back to an
engineering issue.

### All as it amounts to is ... either using bigger
components.... or doing stuff like paralleling 8 x 200pf @ 15
kv HEC ceramic doorknobs to make a plate block cap assy.

With one or two thousand ohms of of RL, 1600pF is not necessary for the DC blocker cap at MF/HF.

...

cheers, Jim

R L MEASURES, AG6K. 805-386-3734
r@...

All,

I started editing the page on transformers at Wikipedia at 6:00 PM
this evening, and it is now 4:30 AM in the morning. I corrected a few
errors from others plus added a complete section on steel used in
transformers. I also added more in the formulas concerning designing
transformers using the square inch measurement for the core. In other
words, I showed the converted metric to inch formulas. I also showed
references to any books I used throughout the page. Below is the links
on some of the sections I corrected, modified, or wrote new.








Transformer#Operation_at_different_frequencies




Transformer#Electrical_Silicon_Steel_Types









That's about it folks, I'm tired and off to bed! Hopefully, some might
add some additional knowledge about RF transformers as it's kind of
lacking (IE ferrite types, powdered iron types, their use, etc).

73,

Will