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On Nov 9, 2006, at 6:09 PM, Robert B. Bonner wrote:

### never had any problems on my L4B's.... use chimneys'. How
fellow's melt the solder on the pins of 3-500Z's on a SB-220 is
beyond me... since the SB-220 fan blows air on the pins.

Easy -- don't lube the fan's porous-bronze sleeve bearings, the fan slows down, the solder melts.

### The slightest bit of DC resistance in a socket... and you
will heat stuff up... fast .

amen, Robert, and with reduced air flow, pins 1 and 5 get hot as hell -- all for want of two drops of oil.

The Professor Says:

You have very little problems with the glass tubes if you keep the airflow
moving in the right direction. Of course the L4B was not too bad. With
chimneys the hotter things get the easier air moves through the chimney.

Without a fan, true, but with a fan the convective effect would be minimal.

You still need help getting the heat out of the cabinet. I cured that with
a big muffin fan on the top with a variac to adjust speed depending on what
I was doing.

The SB-220 Just flat has the air going in all the wrong directions inside
the amplifier.

What would be better than cool air being sucked in the back of the cabinet and blown directly on the hot parts?

When you are doing a contest type operation you are almost
continuously transmitting.

Especially crocodile-types. (all mouth and no ears)

The transformer gets hot, the tubes get hot,
even with muffin fans on top the things still build up a lot of heat in
them. While an 813 will cool well with horizontal air, a 3-500Z just cant
get the job done at max duty.

In aerodynamics, one learns that perpendicular forced-air flows fairly uniformly around all surfaces of a cylinder. This can be seen by watching the smoke plume from a smoldering cotton rope. This principle is what keeps the red marking ink on the 3-500Zs in a SB-220 from toasting to brown like it does in amplifiers that use chimney cooling.

Next thing you know is a perfectly good tube goes dark... Its very hard to
fix too.

Rosin-flux, solder wick, silver-tin solder, and a soldering iron are very hard to use?

I've done it - right up there in the hardest thing to do category.
This happened twice to a contest op I know and I saved him. He now runs a
3X3 in the cruise mode.

Chortle. Translation: Contest-speak for all she's got. Yes, I always run my 4cx15,000Js at 1500w.

I once melted the anode coolers off a set of 4X150's I ended up heating the
coolers on top of my mom's electric stove burners, putting fresh solder into
the cooler and lowering the tubes back into the coolers. They worked fine.

Don't ever have not enough air flow and any vertical or horizontal pressure
on your tube anodes!!! Things come apart.

I also once melted the solder out of a 4 813 amp's suppressors, I had a
bunch of pressure on the resistors and one unsoldered and pulled apart under
the pressure. The amp went from 1000Watts to ZERO instantly with a loud
bang and a huge flash.

36 years ago... AH to be 15 again.

BOB DD

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

On Nov 9, 2006, at 11:46 PM, Tony King - W4ZT wrote:

badgerscreek wrote:
<snip>

YES QEX MAGAZINE IS A RIP OFF CONSIDERING THAT YOU GET 6 ISSUES AND
WHEN YOU FACTOR IN THE MAILING COSTS ITS A HUGE PRICE TO PAY FOR A
FEW ARTICLES. I HATED RENEWING MY SUBSCRIPTION BECAUSE I SINCERELY
BELIEVE EVERYTHING IN QEX COULD BE PLACED IN QST.

<snip>

Greg, I believe it SHOULD be placed in QST. QEX was nothing more than
an effort to get us old timers to BUY another magazine.

Correct, and, according to my source, mo' money was the internal argument presented at Newington before launching QEX. I got the impression that we were being fleeced. My solution was to send a message to Newington by unsubscribing to QST and unsubscribing to QEX.

It HAS to be
more costly to produce QEX as opposed to including the articles in QST.
Seems to me they're boiling QST down and what's left isn't the best
part... some of the recent articles sure make that obvious. When I was a
beginner there were plenty of articles WAY over my head in QST.

This was also my experience in high-school, Tony, but after a few years of additional schooling this changed and I realized that:
1. Designing and building RF transmitting amplifiers isn't akin to rocket science.
2. Many of the articles in QST were difficult to fathom because the author did a somewhat less than ok job of explaining what was going on so that new guys could understand.

Now,
there is little there I want to read. Too bad they can't be RE- combined
to make ONE better magazine.

The problem as I see it is that the powers that be at QST are presently "of, by, and for" something other than amateur radio. I also find it disturbing that the ARRL tries to control the way we use amateur radio bands. Take a look at the 1.8MHz band: There are no ARRL-approved sub-bands. No part of the band is reserved for CW, for AM, for spark. for SSB, for snobs, or for any we're better than you are elite group. We run what mode we want in any clear space we want. Things pretty much sort themselves out, and nobody owns a certain frequency -- with that one exception, of course.
OTOH, take a look at the 3.5MHz band. where many KHz are virtually a vast wasteland because of ARRL-blessed sub-bands.
cheerz

73, Tony W4ZT

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

badgerscreek wrote:
<snip>

YES QEX MAGAZINE IS A RIP OFF CONSIDERING THAT YOU GET 6 ISSUES AND
WHEN YOU FACTOR IN THE MAILING COSTS ITS A HUGE PRICE TO PAY FOR A
FEW ARTICLES. I HATED RENEWING MY SUBSCRIPTION BECAUSE I SINCERELY
BELIEVE EVERYTHING IN QEX COULD BE PLACED IN QST.

<snip>

Greg, I believe it SHOULD be placed in QST. QEX was nothing more than an effort to get us old timers to BUY another magazine. It HAS to be more costly to produce QEX as opposed to including the articles in QST. Seems to me they're boiling QST down and what's left isn't the best part... some of the recent articles sure make that obvious. When I was a beginner there were plenty of articles WAY over my head in QST. Now, there is little there I want to read. Too bad they can't be RE-combined to make ONE better magazine.

73, Tony W4ZT

### never had any problems on my L4B's.... use chimneys'. How
fellow's melt the solder on the pins of 3-500Z's on a SB-220 is
beyond me... since the SB-220 fan blows air on the pins.

### The slightest bit of DC resistance in a socket... and you
will heat stuff up... fast .

The Professor Says:

You have very little problems with the glass tubes if you keep the airflow
moving in the right direction. Of course the L4B was not too bad. With
chimneys the hotter things get the easier air moves through the chimney.
You still need help getting the heat out of the cabinet. I cured that with
a big muffin fan on the top with a variac to adjust speed depending on what
I was doing.

The SB-220 Just flat has the air going in all the wrong directions inside
the amplifier. When you are doing a contest type operation you are almost
continuously transmitting. The transformer gets hot, the tubes get hot,
even with muffin fans on top the things still build up a lot of heat in
them. While an 813 will cool well with horizontal air, a 3-500Z just cant
get the job done at max duty.

Next thing you know is a perfectly good tube goes dark... Its very hard to
fix too. I've done it - right up there in the hardest thing to do category.
This happened twice to a contest op I know and I saved him. He now runs a
3X3 in the cruise mode.

I once melted the anode coolers off a set of 4X150's I ended up heating the
coolers on top of my mom's electric stove burners, putting fresh solder into
the cooler and lowering the tubes back into the coolers. They worked fine.

Don't ever have not enough air flow and any vertical or horizontal pressure
on your tube anodes!!! Things come apart.

I also once melted the solder out of a 4 813 amp's suppressors, I had a
bunch of pressure on the resistors and one unsoldered and pulled apart under
the pressure. The amp went from 1000Watts to ZERO instantly with a loud
bang and a huge flash.

36 years ago... AH to be 15 again.

BOB DD

On Nov 9, 2006, at 2:17 PM, David C. Hallam wrote:

Tony Wrote

I'd be interested in the article (wonder why ARRL puts good technical
articles in QEX instead of QST?) but I don't see huge rheostats for
filaments either.

I think that is fairly obvious. Most hams today wouldn't understand them
and don't care, and the ARRL can make more money selling another magazine.

As I understand it, the last reason is correct. In the first and last article I wrote for QEX, the ARRL's copy-editor added 5 technical errors to my manuscript.

David
KC2JD

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

On Nov 9, 2006, at 1:48 PM, pentalab wrote:

OK... I'll bite. What exactly is Orr's... "super cathode driven"
circuit all about ??

The driving signal is applied between the cathode and the screen instead of between the cathode and the grid, and the control grid is connected to the cathode. Thus, the gain is c. the same as the screen amplification factor.

Is this simply semi floating the grids on a
3-500Z.... or something else ?

25 years ago.... there was this circuit for a 4CX-1000.... and I
thought it was called "super cathode driven".... might be wrong...
believe it was in either cq or 73 rag. If I remember correctly...
Drive was applied to both the cathode and the control grid at the
same time... and the screen grid was grndned for RF.

Correct. ...

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

--- In ham_amplifiers@..., GGLL <nagato@...> wrote:

How will perform the socket contacts at such filament

current??. With only

15A (3-500z) I've seen many contact failures, so I figure with

that tube it

will be a must to blow air directly to the pins.

Bewt regards
Guillermo - LU8EYW.

### good question. I was told that the Eimac SK-410 will easily
handle 26 A. Ditto with a SK-510 [4-1000 socket. Some versions
of the 4-1000 ran 7.5 v @ 26 A]


### Nobody said anything about stuffing 30 A through them. Dunno
about other brands of sockets... like those used in the Ameritron AL-
82


## Dunno about the Johnson sockets... at least they have... 'helper
springs".

### On my 2 x 4-400 amp [built by someone else]... the fil pins
were extremely hot.... so I added a squirell cage blower. Of course
the fellow who built it, has the tubes too close... so u can't
install chimneys on em.

### never had any problems on my L4B's.... use chimneys'. How
fellow's melt the solder on the pins of 3-500Z's on a SB-220 is
beyond me... since the SB-220 fan blows air on the pins.

### The slightest bit of DC resistance in a socket... and you
will heat stuff up... fast .

### another reason why I like these socketless tubes... zero
problems. No problems with the 3x3 / 3x6 socket from RF parts...
except it is expensive.

later... Jim VE7RF

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

a cheap and reliable methode is the magnetic regulator,
I use choke regulated heater transformers.
There is no need for fast regulation.

73
Peter

### What is a.... "choke regulated heater xfmr" ??

### What is a ...."magnetic regulator" ?

### How fast is fast ?? As fast as practical ?? My idea of
using a sola ferroresonant xfmr... was now I don't have to ever
worry about my fluctating line V. Seasonal variations aside...
and /or just going ftom RX to TX..... the line V can go up/down
or sideways.... the fil V doesn't budge an inch.

Later... Jim VE7RF

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

I'd be interested in the article (wonder why ARRL puts good

technical articles in QEX instead of QST?) but I don't see huge
rheostats for filaments either.

### I wonder the same thng.... probably to promote sales
of .."QEX". They have one too many publications imo.

### Fil V can be of concern...esp when sucking vast amounts of
current for the plate xfmr. On a set up where the fil xfmr pri

V

is derived from the same 240 V source as the plate pri....

under a

full bore load... the fil V can be affected.

Especially with indirectly heated cathodes. They are much more

likely to

be damaged by changing filament voltages, especially low voltages.

#### agreed.,

### One way out of this mess, is to run a separate, smaller 240

V

line... just for the fil xfmr pri. That might not solve all

the

fil sag problems... but at least the separate fil 240 v

supply...

will only have the v drop on your drop wires coming into your
home, to contend with. If anybody goes this route... make

sure

you label.. "more than one live circuit present". You are

gonna

have to kill TWO sets of breakers to completely kill all 240

v

coming into the amp. In cases where the RF deck is totally
separate from the HV supply, it may not be an issue.

And if you have line voltage variations that are common,

especially in areas where high air conditioning loads are the norm,
even separate circuits wont help.

### You are probably right. My buddy's 3x6.... between no load
and dead cxr... is 241 v..... down to 236.5 v... a 4.5 v instant
drop. Until we measure how much of that is from the 2 ga wire from
HV /fil supply to main 200A panel... and how much is from drop
wires coming from the street... will determine if a separate 240
v line... just for the fils, will actually help.

### another method is to use a sola constant V xfmr.

And they get hot! That means they waste LOTS of power... and that

is not a good thing. If you're going to consume lots of power,
let's convert at least half of it to RF ;)

#### Unloaded... they get hot after 1-2 hrs. But so does my Dahl
fil xfmr... with no lod on it either. One night, I left the dahl
on for several hrs.. forgot abt it... and it was HOT. With a full
bore 70-79 A load on it... it's barely luke warm ! The sola's
are sorta the same way... they run cooler with a load on em..... so
if used... you don't want to oversize em. A 500 va sola is fine
for a 375 va fil... and a 750 va sola is fine for a 560 va
fil. You want at least a 40-50% load on a sola.

### The absolute ideal scenario is to use a separate 240 v line...
[separte from the 2 ga wire to the HV supply]... directly to the
SOLA.... then to variac... then to dahl filo xfmr.



## I don't use the variac for step start

either. The variac.. once set.. stays put. A 25 ohm 100/150

w metal finned resistor in one leg of the 240 V, feeding the fil
xfmr primary.. and a 8 second delay, is used.

Later... Jim VE7RF

Jim, isn't 8 seconds a bit long for your step start? That's 480

cycles at 60 Hz. Even with the huge capacitor bank and a good step
start, it should be up to snuff long before then shouldn't it?

#### The 8 seconds was the step start on the FIL. We used a 0-30
timer... and arbitrarily 5-10 seconds for the FIL. The 25 ohm
resistor in one leg limits the fil V to exactly 75%. I'm
wondering if we should be limiting the V to 50-60% ?? We could
have just used the fil variac as a step start each time. But, the
fil variac was carefully dialled in, to give full bore out... with
the least fil V... and in this case... after 200 hrs... the fil V
was reduced from 7.0 down to just 6.1 V. Another concern was
IF the power went out from the power co in winter.... then when it
came back on... and IF fil variac still cranked up.... there would
be No step start....../ hence the 8 second delay circuit.

### Now, per this latest PDF from Reid Brandon on the YC-243....
it's saying all these big metal tubes are designed for commercial
service.... one on and one off cycle per day..... and don't keep
cycling the fil on/off several times a day. With either step
start.. and /or a variac... that shouldn't be a problem... esp bring
up a variac real slow. The 25 ohm fil step start just slams the
juice on.... it's not like charging caps up in a hv supply. It's
75% fil V... now.



### The big HV supply has a 14-18 second delay... 7900v + a 135
uf filter. You can bring it up pretty good in 5 seconds.... but
the extra 10 seconds keeps bringing it up.. slowly. When step start
finally activates... minimal secondary surge. We were in no big
rush. 1/2 V is only 1/4 charged up on hv caps. Energy storage
goes to the square of the V. You need the V on the caps to almost
70% ... just to get em 1/2 charged up.

### BTW... I saw ur sub mounted socket scheme for the russian
tube .. superb.. now I get it. Pix was obvious.

Later... Jim VE7RF

73, Tony W4ZT

a cheap and reliable methode is the magnetic regulator,
I use choke regulated heater transformers.
There is no need for fast regulation.

73
Peter

________________________________

From: ham_amplifiers@... [mailto:ham_amplifiers@...]
On Behalf Of hinrgdj1

### Fil V can be of concern...esp when sucking vast amounts of
current for the plate xfmr. On a set up where the fil xfmr pri

V

is derived from the same 240 V source as the plate pri.... under

a

full bore load... the fil V can be affected.

Especially with indirectly heated cathodes. They are much more

likely to

be damaged by changing filament voltages, especially low voltages.

### One way out of this mess, is to run a separate, smaller 240

V

line... just for the fil xfmr pri. That might not solve all

the

fil sag problems... but at least the separate fil 240 v supply...
will only have the v drop on your drop wires coming into your
home, to contend with. If anybody goes this route... make sure
you label.. "more than one live circuit present". You are

gonna

have to kill TWO sets of breakers to completely kill all 240

v

coming into the amp. In cases where the RF deck is totally
separate from the HV supply, it may not be an issue.

And if you have line voltage variations that are common, especially

in

areas where high air conditioning loads are the norm, even separate
circuits wont help.

### I have the fil xfmr, and associated variac for it.. + a
sola constant V xfmr.. in a shelf... below RF deck.... so RF

deck

is in top of rack... fil stuff is below... in same rack. HV

supply

is in a separate rack.

+++ C&H Sales has a sweet SOLA CVS, rack/floor mount that will handle
a single YC-156/179 or +++GS-35B's, metered in/outs...plus other
120vac control/rotors/etc. up to 500VA output...(best to load heavy
for best regulation). Their Stock #STR9900

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

pentalab wrote:

--- In ham_amplifiers@..., "badgerscreek" <qrp73@>
wrote:

There is a nice article published in the latest QEX. Its for a
filament voltage regulator. Its Titled " A high Efficiency

Filament

regulator" K8LV. It uses a PIC and some pass resistors. It

seems

any size tube is accomodated by increasing pass transistor sizes,

including bumping up heatsink sizes. It also has a ramp up

feature. My guestimate suggests that it would be cheaper

building

this regulator than buying 2 X 50 or 100 watt rheostats.

Greg

### Greg.... how would 2 x 50/100 w rheostats regulate fil
V ?? Or are they using pass transistor's in a regulator ?

I'd be interested in the article (wonder why ARRL puts good

technical

articles in QEX instead of QST?) but I don't see huge rheostats for
filaments either.

### Fil V can be of concern...esp when sucking vast amounts of
current for the plate xfmr. On a set up where the fil xfmr pri

V

is derived from the same 240 V source as the plate pri.... under

a

full bore load... the fil V can be affected.

Especially with indirectly heated cathodes. They are much more

likely to

be damaged by changing filament voltages, especially low voltages.

### One way out of this mess, is to run a separate, smaller 240

V

line... just for the fil xfmr pri. That might not solve all

the

fil sag problems... but at least the separate fil 240 v supply...
will only have the v drop on your drop wires coming into your
home, to contend with. If anybody goes this route... make sure
you label.. "more than one live circuit present". You are

gonna

have to kill TWO sets of breakers to completely kill all 240

v

coming into the amp. In cases where the RF deck is totally
separate from the HV supply, it may not be an issue.

And if you have line voltage variations that are common, especially

in

areas where high air conditioning loads are the norm, even separate
circuits wont help.

### I have the fil xfmr, and associated variac for it.. + a
sola constant V xfmr.. in a shelf... below RF deck.... so RF

deck

is in top of rack... fil stuff is below... in same rack. HV

supply

is in a separate rack.

+++ C&H Sales has a sweet SOLA CVS, rack/floor mount that will handle
a single YC-156/179 or +++GS-35B's, metered in/outs...plus other
120vac control/rotors/etc. up to 500VA output...(best to load heavy
for best regulation). Their Stock #STR9900

73, Mike WD4EFI

Tony Wrote

I'd be interested in the article (wonder why ARRL puts good technical
articles in QEX instead of QST?) but I don't see huge rheostats for
filaments either.

I think that is fairly obvious. Most hams today wouldn't understand them
and don't care, and the ARRL can make more money selling another magazine.

David
KC2JD

pentalab escribi:

Reid Brandon at Eimac phoned me today. Reid passed this important info along. The correct phone number for Arnold Howell [KB8JCY] of Howell Tube Sales is 330-744-7582. Make sure to *82 1st... to shut OFF your call block [if u have auto block]. Arnold returns calls fairly promptly. Also, Arnold Howell's CORRECT e-mail address is ... KB8JCY @ AOL.com His snail mail address is PO Box 5842, Youngstown, OHIO, Zip- 44504 He has NO website.
Also had Arnold Howell himself, phone me this afternoon. Howell had Eimac build a... "hot rod" version of a 3CX-1200.... called a YU-
120. This is the 1500w anode dissipation version... with a 6.3 V @ 26 A filament. There is also another version... called a 3CX-
1500D7. The 1500D7 version is the same 1500 w anode dissipation.... EXCEPT the fil is 5.0 V @ 30 A. BOTH versions of these tubes are thoriated tungsten fils, instant on, and both use a SK-410 [or any version of a 3-500Z socket, like the Johnston] socket. He also has the custom Teflon chimney's for them.

How will perform the socket contacts at such filament current??. With only 15A (3-500z) I've seen many contact failures, so I figure with that tube it will be a must to blow air directly to the pins.

Bewt regards
Guillermo - LU8EYW.

pentalab wrote:

--- In ham_amplifiers@..., "badgerscreek" <qrp73@...> wrote:

There is a nice article published in the latest QEX. Its for a
filament voltage regulator. Its Titled " A high Efficiency

Filament

regulator" K8LV. It uses a PIC and some pass resistors. It seems

any size tube is accomodated by increasing pass transistor sizes,

including bumping up heatsink sizes. It also has a ramp up

feature. My guestimate suggests that it would be cheaper building this regulator than buying 2 X 50 or 100 watt rheostats.

Greg

### Greg.... how would 2 x 50/100 w rheostats regulate fil V ?? Or are they using pass transistor's in a regulator ?

I'd be interested in the article (wonder why ARRL puts good technical articles in QEX instead of QST?) but I don't see huge rheostats for filaments either.

### Fil V can be of concern...esp when sucking vast amounts of current for the plate xfmr. On a set up where the fil xfmr pri V is derived from the same 240 V source as the plate pri.... under a full bore load... the fil V can be affected.

Especially with indirectly heated cathodes. They are much more likely to be damaged by changing filament voltages, especially low voltages.

### One way out of this mess, is to run a separate, smaller 240 V line... just for the fil xfmr pri. That might not solve all the fil sag problems... but at least the separate fil 240 v supply... will only have the v drop on your drop wires coming into your home, to contend with. If anybody goes this route... make sure you label.. "more than one live circuit present". You are gonna have to kill TWO sets of breakers to completely kill all 240 v coming into the amp. In cases where the RF deck is totally separate from the HV supply, it may not be an issue.

And if you have line voltage variations that are common, especially in areas where high air conditioning loads are the norm, even separate circuits wont help.

### I have the fil xfmr, and associated variac for it.. + a sola constant V xfmr.. in a shelf... below RF deck.... so RF deck is in top of rack... fil stuff is below... in same rack. HV supply is in a separate rack.
### another method is to use a sola constant V xfmr. These are all of the ferroresonant type. Mine has input taps for
118....208....236 v. The output side is a constant 236 /118 V It regulates very well. You can swing the input Voltage a huge amount on either side of a particular input tap... and output side remains constant. These things are HEAVY though.... my 750Va unit weighs 65lbs. I have seen em in 250-500-750-1000-2000 va. Fair radio had tons of em.... some brand new in the box.... dirt cheap.

And they get hot! That means they waste LOTS of power... and that is not a good thing. If you're going to consume lots of power, let's convert at least half of it to RF ;)

### A SS regulated method might be the ticket....would be lighter. How much fil POWER can these things handle ? Are they RELIABLE ? The last thing anybody needs is a regulator to crap out... and fil V increase... even a few percent.

I have used some 12 Volt switchers for GS-35B supplies with good luck. They are slow starting and have over voltage and over current protection built in. RF Noise, if any, can be easily controlled with the switcher living inside the cabinet where you can properly filter it.

### Another related issue is seasonal line V regulation. I have seen mine as high as 247.2 V at 1 AM in the summertime [122.2 + 125 =247.2] Usually , in the dead of winter, at dinner time, it's 240v, or 239.9v. Last week, it's 234V [117+117]... and that was at 2 pm on a sunday afternoon... go figure. Point here is the variation is from 247.2 v... down to 234V... and that's just measuring the V with HV supply OFF... no big load.
With a big load on thr plate xfmr.. it's going to get sucked down even more. Changing taps on a plate xfmr is one thing... having to constantly be tweaking a fil variac is a real pain... and impossible to do between RX/TX. I don't use the variac for step start either. The variac.. once set.. stays put. A 25 ohm 100/150 w metal finned resistor in one leg of the 240 V, feeding the fil xfmr primary.. and a 8 second delay, is used. Later... Jim VE7RF

Variations in the plate voltage wont do the harm that variations in filament might so I'll take whatever comes out so long as it doesn't exceed the component ratings (not in this life time!)

Jim, isn't 8 seconds a bit long for your step start? That's 480 cycles at 60 Hz. Even with the huge capacitor bank and a good step start, it should be up to snuff long before then shouldn't it?

73, Tony W4ZT

OK... I'll bite. What exactly is Orr's... "super cathode driven"
circuit all about ?? Is this simply semi floating the grids on a
3-500Z.... or something else ?

25 years ago.... there was this circuit for a 4CX-1000.... and I
thought it was called "super cathode driven".... might be wrong...
believe it was in either cq or 73 rag. If I remember correctly...
Drive was applied to both the cathode and the control grid at the
same time... and the screen grid was grndned for RF. I still know
of two of those 4CX-1000 amps that are still round.. within 200
miles of me. The kicker was.... it required 160 watts to drive
it to 1200 w out. At the time it was no big deal... since the
xcvr's used were FT-DX-400/401's.

### a local across town from me in the 80's built one.... took
out 100 khz of 20m with it.... not imd... but shot noise. My
Drake R4C noise-blanker took it right out on RX... and I could then
get real close to him... within 15 khz. We both had yagi's up
70'.... and only 2500' apart. He subsequently found the problem...
never was told what the problem actually was. His xcvr at the
time was a 101ZD...with 6146W finals.

## The guy's with the FT-DX-400/401 xcvr's had clean sigs on
75m... so the concept worked... albeit... not a lot of gain ...
8.75db

Later... Jim VE7RF

A CV transformer is uneffected by RF. An active regulator will have to be properly shielded so RF doesn't modulate it. I saw it as a cool idea but the failure modes could be a problem. gfz

pentalab wrote:

--- In ham_amplifiers@..., "badgerscreek" <qrp73@...>
wrote:

There is a nice article published in the latest QEX. Its for a
filament voltage regulator. Its Titled " A high Efficiency

Filament

regulator" K8LV. It uses a PIC and some pass resistors. It seems

any size tube is accomodated by increasing pass transistor sizes,

including bumping up heatsink sizes. It also has a ramp up

feature. My guestimate suggests that it would be cheaper building
this regulator than buying 2 X 50 or 100 watt rheostats.

Greg

### Greg.... how would 2 x 50/100 w rheostats regulate fil
V ?? Or are they using pass transistor's in a regulator ?

### Fil V can be of concern...esp when sucking vast amounts of
current for the plate xfmr. On a set up where the fil xfmr pri V
is derived from the same 240 V source as the plate pri.... under a
full bore load... the fil V can be affected.

### One way out of this mess, is to run a separate, smaller 240 V
line... just for the fil xfmr pri. That might not solve all the
fil sag problems... but at least the separate fil 240 v supply...
will only have the v drop on your drop wires coming into your
home, to contend with. If anybody goes this route... make sure
you label.. "more than one live circuit present". You are gonna
have to kill TWO sets of breakers to completely kill all 240 v
coming into the amp. In cases where the RF deck is totally
separate from the HV supply, it may not be an issue.

### I have the fil xfmr, and associated variac for it.. + a
sola constant V xfmr.. in a shelf... below RF deck.... so RF deck
is in top of rack... fil stuff is below... in same rack. HV supply
is in a separate rack.


### another method is to use a sola constant V xfmr. These are all
of the ferroresonant type. Mine has input taps for
118....208....236 v. The output side is a constant 236 /118 V
It regulates very well. You can swing the input Voltage a huge
amount on either side of a particular input tap... and output side
remains constant. These things are HEAVY though.... my 750Va unit
weighs 65lbs. I have seen em in 250-500-750-1000-2000 va. Fair
radio had tons of em.... some brand new in the box.... dirt cheap.

### A SS regulated method might be the ticket....would be lighter.
How much fil POWER can these things handle ? Are they RELIABLE ?
The last thing anybody needs is a regulator to crap out... and fil
V increase... even a few percent.

### Another related issue is seasonal line V regulation. I have
seen mine as high as 247.2 V at 1 AM in the summertime [122.2 +
125 =247.2] Usually , in the dead of winter, at dinner time,
it's 240v, or 239.9v. Last week, it's 234V [117+117]... and that
was at 2 pm on a sunday afternoon... go figure.

Point here is the variation is from 247.2 v... down to 234V... and
that's just measuring the V with HV supply OFF... no big load.
With a big load on thr plate xfmr.. it's going to get sucked down
even more. Changing taps on a plate xfmr is one thing... having to
constantly be tweaking a fil variac is a real pain... and impossible
to do between RX/TX. I don't use the variac for step start
either. The variac.. once set.. stays put. A 25 ohm 100/150 w
metal finned resistor in one leg of the 240 V, feeding the fil xfmr
primary.. and a 8 second delay, is used.

Later... Jim VE7RF

On Nov 8, 2006, at 11:48 PM, Rick xxxx wrote:

Just looking around.

Hi to Rich!

Longtime no hear!

Remember that excursion to Mt Pinos for the VHF contest in the 70's?

My last VHF Contest was a few miles East of Mt. Pi?os on Frasier
Mountain. What is your callsign?

73/Rick

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

Reid Brandon at Eimac phoned me today. Reid passed this important
info along.

The correct phone number for Arnold Howell [KB8JCY] of Howell Tube
Sales is 330-744-7582. Make sure to *82 1st... to shut OFF your
call block [if u have auto block]. Arnold returns calls fairly
promptly. Also, Arnold Howell's CORRECT e-mail
address is ... KB8JCY @ AOL.com His snail mail address is PO
Box 5842, Youngstown, OHIO, Zip- 44504 He has NO website.

Also had Arnold Howell himself, phone me this afternoon. Howell had
Eimac build a... "hot rod" version of a 3CX-1200.... called a YU-
120. This is the 1500w anode dissipation version... with a 6.3 V
@ 26 A filament. There is also another version... called a 3CX-
1500D7. The 1500D7 version is the same 1500 w anode
dissipation.... EXCEPT the fil is 5.0 V @ 30 A. BOTH versions of
these tubes are thoriated tungsten fils, instant on, and both use a
SK-410 [or any version of a 3-500Z socket, like the Johnston] socket.
He also has the custom Teflon chimney's for them.

Howell also tells me, he has 20-24 x YC-179's available... $400.00
plus shipping. He also has access to hypersil pole pigs... most
in 4160+ 4800 V taps.... and also 7200 V...... all in 5-10-15-25
Kva... with, OR without the oil. He also has some 4CX-10,000D's,
and 4CX-5000A's available. Also available, are blowers for 3CX-
10,000A7's, etc.

The story on the YC-243 [socketless version of the 3CX-6000A7 /YU-
148] is... he needs a minimum order of 10 [TEN] to justify a small
production run by Eimac. Apparently,[no surprise], costs go down,
with volume... and tubes are bought in either quantities 1-4.... 5-
9.... 10-49..... 50-XXX.

The YC-243 is ONLY available from Howell.. not anyone else.. like
Richardson. The "YC" designator means it's a custom made tube for
a client. The YC-243 rebuild process is done by Freeland.[Way
better price than Econco... both are 2 x biggest tube rebuilder's
about].... so it can be rebuilt over and over again.

The tube has identical electrical specs to a 3CX-6000A7. Reid Brandon
e-mailed me the official Eimac PDF document on the YC-243. This
version contains ALL the 'typ' operating parameter's for AB2
operation... like Cathode Driven AM operation.... Cathode Driven AB-
2 SSB..... And Class C, Cathode driven CW operation. [The
Eimac 3CX-6000A7 literature is for AB-2 FM broadcast..... the
Svetlana specs also include Class C FM broadcast, with loads of bias]

The biggest feature of the YC-243, is the expensive socket [now
$375.00 from RF parts] is NOT required.... being a socketless tube.

Per the Eimac spec's... the input Z is 50 ohms. I found some minor
discrepancies and typo's between the YC-243 spec sheet + the 6000A7
sheet... and these will be corrected.

Told Reid about the increase in anode diss, that's possible with a
lower intake air temp... AND increased airflow.... AND described the
9.5" square box built around the tube.... with a solid teflon top.
He agreed any TAPERED cone shaped chimney, should be at LEAST 8"
diam... and pref even bigger. Both Howell and Economy Electronics
make straight up/down chimney's for this tube.[6.3" ID]... but Reid
agreed... both those versions restrict the airflow way too much.
I'm going to forward him my finding's.. and measurements, of what
our 'typ' operation is.

So the short of it...a min of 10 x tubes [in total], needs to be
ordered by Howell...from Eimac. Contact Howell, if you are
interested.

Later.... Jim VE7RF

Just looking around.

Hi to Rich!

Longtime no hear!

Remember that excursion to Mt Pinos for the VHF contest in the 70's?



73/Rick