开云体育

--- 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

I often order HV transformer from a local shop. price: RMB2 per VA(25C/VA),
a 1000VA CCS HV xfmer =$253(TYPE R or C iron core), if it is "EI" type iron core,
the price is $150.
73! Hsu

Try this again since it claimed to post it then didn't.

That transformer looks somewhat familiar. There's a company just
outside of LA named WTS which is short for Woodys Transformer Service
that wound transformers for most 11 meter tube amps made in
California and the surrounding states. I bought them also since the
cost was low enough that after paying higher shipping, I still came
out. I don't have a URL for them.

Most down south (amplifier alley) building amps use Galaxy
Transformer in New Jersy. They make a custom transformer to work with
an alternator that has the rectifiers removed making it an AC 3 phase
generator. In other words it has a 14 Vac 3 phase primary. That was
an old way to run tube mobile amps.

Their URL is;

www.galaxytransformers.com

Best,

Will

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

Gent's

Check this out..... plus it's an interesting site worth
bookmarking.



Then, after u have added it to ur shopping buggy.... all u gotta

do

is get ur local power co to upgrade the pole pig + drop wires in
front of ur home!

A real steal... compared to that $8750.00 Alpha.

I'd suggest using the 7073 vac tap... which will give you 10 kv
dc under load. This is the perfect xfmr ...for a pair of 3CX-
20,000A/C7's. Also suitable for a pair of 4CX-15/20 K's. All

those

tubes are rated at 10 kv @ 6 A. Now I'd highly recomend a Buss

10-

kv HV sand-filled fuse [10" long] Dunno about a "glitch
R"...perhaps a paralleled pair of those 50 ohm 1 kw globars

[2"diam

x 24" long]


Later.... Jim VE7RF

That transformers construction looks familiar. Several of us used a
transformer manufacturer just outside of LA which was called Woodys
transformer at the time. They wound about all the transformers for
the 11 meter amps made in California and surroundng states. Woody
retired and his son now runs the company. I think it's now called
"WTS" which is short for Woodys Transformer Service. They had some of
the best prices available for HV transformers. They were so cheap
that I could pay the shipping to Ohio and still come out ahead. That
was buying like 10-20 transformers at a time. There single lot price
is almost as cheap. I don't have a website for them though.

Some of the other builders down south (amplifier alley) who are still
in business use Galaxy Transformer in New Jersey. They make some
special transformers to be used with an alternator less the
rectifiers/voltage reg. making it a 3 phase generator. The primary
then is about 14 Vac, 3 phase. The secondaries can be any voltage
needed. That's an easy way to run a big tube mobile.

Their website is;



Best,

Will




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

Gent's

Check this out..... plus it's an interesting site worth
bookmarking.



Then, after u have added it to ur shopping buggy.... all u gotta

do

is get ur local power co to upgrade the pole pig + drop wires in
front of ur home!

A real steal... compared to that $8750.00 Alpha.

I'd suggest using the 7073 vac tap... which will give you 10 kv
dc under load. This is the perfect xfmr ...for a pair of 3CX-
20,000A/C7's. Also suitable for a pair of 4CX-15/20 K's. All

those

tubes are rated at 10 kv @ 6 A. Now I'd highly recomend a Buss

10-

kv HV sand-filled fuse [10" long] Dunno about a "glitch
R"...perhaps a paralleled pair of those 50 ohm 1 kw globars

[2"diam

x 24" long]


Later.... Jim VE7RF

That transformers construction looks familiar. Several of us used a
transformer manufacturer just outside of LA which was called Woodys
transformer at the time. They wound about all the transformers for
the 11 meter amps made in California and surroundng states. Woody
retired and his son now runs the company. I think it's now called
"WTS" which is short for Woodys Transformer Service. They had some of
the best prices available for HV transformers. They were so cheap
that I could pay the shipping to Ohio and still come out ahead. That
was buying like 10-20 transformers at a time. There single lot price
is almost as cheap. I don't have a website for them though.

Some of the other builders down south (amplifier alley) who are still
in business use Galaxy Transformer in New Jersey. They make some
special transformers to be used with an alternator less the
rectifiers/voltage reg. making it a 3 phase generator. The primary
then is about 14 Vac, 3 phase. The secondaries can be any voltage
needed. That's an easy way to run a big tube mobile.

Their website is;



Best,

Will




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

Gent's

Check this out..... plus it's an interesting site worth
bookmarking.



Then, after u have added it to ur shopping buggy.... all u gotta

do

is get ur local power co to upgrade the pole pig + drop wires in
front of ur home!

A real steal... compared to that $8750.00 Alpha.

I'd suggest using the 7073 vac tap... which will give you 10 kv
dc under load. This is the perfect xfmr ...for a pair of 3CX-
20,000A/C7's. Also suitable for a pair of 4CX-15/20 K's. All

those

tubes are rated at 10 kv @ 6 A. Now I'd highly recomend a Buss

10-

kv HV sand-filled fuse [10" long] Dunno about a "glitch
R"...perhaps a paralleled pair of those 50 ohm 1 kw globars

[2"diam

x 24" long]


Later.... Jim VE7RF

On Nov 8, 2006, at 12:47 AM, pentalab wrote:

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

RICH SEZ.... In my experiences, the G2DAF design is c. 11db

cleaner
with a 2-tone modulation test than it is with voice modulation.
With voice modulation, total IMD is c. 21db below pep.

### I have a 2 x 4-400 G2DAF linear. About 900w out with 75
w
of drive... and only 2700 V. Any more than 75 w of drive... and
it
won't do any more than 900w.

### The secret with the g2DAF design is selcting the PRECISE values
of screen caps to charge up. Too small... and u are outa luck....
too big... and all the energy gets diverted into charging em up. A
friend here in town built several 4 x hole 4CX-250B linear's..
and
also several 2 x 4-1000 linears... all in G2DAF. The 4CX-250B
design came straight from G2DAF himself... back in 1968/69. You
can't just take the original 813 design... and stuff any tetrode
into it. It has to be tweaked just right... for a specific tube.

### My 2 x 4-400 was built by the local RI here in town... uses a
4:1 un-un to step up the Z to 200 ohms... then terminated into
200
ohms.

### IMD on ssb is better than I thought. We ran several tests here
in town.... NOBODY bitched about IMD. I could switch it with a GG
linear in under 1 second... and nobody heard the difference. Not
one
of my favourite designs.... but done exactly right... it works
good. Done wrong... and it's not as clean as could be.

## It changes class as drive cycle increases. The whole thing
hinges on charge rate of the screen caps.... get em wrong.. and IMD
will go to hell.

### I have heard several 4-1000 G2DAF linears on ssb.... also
switched to 4-1000 GG [2nd linear] in mid sentence.... while a few
of us monitoring off freq [some up.. some down]. Damned if we could
hear any diff on or off freq. I have also heard some 4-400 G2DAF
linears that were nothing but problems. They are a trick to get
just right.... so u just can't right em all off as.. "bad".

### With no drive applied... no screen V is developed... and no
idle
current... tube cut off..... it saves a complicated, possibly
failure prone regulated screen supply.. + 2 x bias supplies, [RX +
TX].... + NO tuned input required... since it's terminated in a
globar. They look + sound very good on CW too..

On CW, Class C sounds delightsome.

.. so it DOES
have
some merits. Somebody In EU.. thought SM land... has a 4CX-10,000
in G2DAF.... who swears by it IMD wise.

Those who operate 5kHz from a G2DAF swear at the IMD. Here in the land of fruits and nuts (California) I have listened to three of them on 40m and 80m. All were ok with a 2-tone test, but with a human voice they definitely did not cause others to rejoice.
As I understand it, G2DAF did not know how to go about building a regulated screen supply, and that's why he came up with his cockamamie idea of a virtually Class C linear with Class C levels of efficiency.

Dunno what gain it
has.....
a lot less than if a real screen supply used..... and a bit better
than GG.

### My 1st choice would still be a hi MU triode in GG.

The 8160 high-Mu triode requires c. 1500w to drive it nicely. An 8171 or 8281 tetrode in AB1 can be driven with 170w . However the g- g triode is cleaner, but OTOH the input circuitry for AB1 grid-driven is easier to build.

Later.... Jim VE7RF

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

Yahoo! Groups Links

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

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

RICH SEZ.... In my experiences, the G2DAF design is c. 11db

cleaner
with a 2-tone modulation test than it is with voice modulation.
With voice modulation, total IMD is c. 21db below pep.

### I have a 2 x 4-400 G2DAF linear. About 900w out with 75
w
of drive... and only 2700 V. Any more than 75 w of drive... and
it
won't do any more than 900w.

### The secret with the g2DAF design is selcting the PRECISE values
of screen caps to charge up. Too small... and u are outa luck....
too big... and all the energy gets diverted into charging em up. A
friend here in town built several 4 x hole 4CX-250B linear's..
and
also several 2 x 4-1000 linears... all in G2DAF. The 4CX-250B
design came straight from G2DAF himself... back in 1968/69. You
can't just take the original 813 design... and stuff any tetrode
into it. It has to be tweaked just right... for a specific tube.

### My 2 x 4-400 was built by the local RI here in town... uses a
4:1 un-un to step up the Z to 200 ohms... then terminated into
200
ohms.

### IMD on ssb is better than I thought. We ran several tests here
in town.... NOBODY bitched about IMD. I could switch it with a GG
linear in under 1 second... and nobody heard the difference. Not
one
of my favourite designs.... but done exactly right... it works
good. Done wrong... and it's not as clean as could be.

## It changes class as drive cycle increases. The whole thing
hinges on charge rate of the screen caps.... get em wrong.. and IMD
will go to hell.

### I have heard several 4-1000 G2DAF linears on ssb.... also
switched to 4-1000 GG [2nd linear] in mid sentence.... while a few
of us monitoring off freq [some up.. some down]. Damned if we could
hear any diff on or off freq. I have also heard some 4-400 G2DAF
linears that were nothing but problems. They are a trick to get
just right.... so u just can't right em all off as.. "bad".

### With no drive applied... no screen V is developed... and no
idle
current... tube cut off..... it saves a complicated, possibly
failure prone regulated screen supply.. + 2 x bias supplies, [RX +
TX].... + NO tuned input required... since it's terminated in a
globar. They look + sound very good on CW too.... so it DOES
have
some merits. Somebody In EU.. thought SM land... has a 4CX-10,000
in G2DAF.... who swears by it IMD wise. Dunno what gain it
has.....
a lot less than if a real screen supply used..... and a bit better
than GG.

### My 1st choice would still be a hi MU triode in GG.

Later.... Jim VE7RF

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

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

Yeah who needs fuses?

Current limit with the power company.

Hello? Yes this is NUKE STATION #6, yes this is SM2EKM I'm coming

on line, pull the rods out.

### Yeah ! Pull the rods ALL the way out ! ROFLMAO

### Later... Jim VE7RF

Hee hee.

Thanks Bob, nice to start the day with a nice laugh.

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

Robert B. Bonner wrote: