3CX vs 4CX tube
G SEVEN
Who can answer this question please, I was looking at the Eimac specs for
various tubes and I noticed that between the 3CX nad 4CX there was a
difference. The difference was in amplification factor, the 3CX had up to
200 times amplification factor were is the 4CX only had 4.3
The 4CX had more output watts but less amplification factor. Can someone
explain this? and what's the better tube and why?
thanks,
KRS
Richard McCollum
"G SEVEN" <superiorw...@prodigy.net> wrote in message
news:8h56cv$1uqq$1...@newssvr03-int.news.prodigy.com...
Are you reading the spec sheet correctly??? In EiMac nomenclature, the 3s
are triodes and the 4s are tetrodes so the spec sheets probably do not line
up with each other. As for what is better that is a question that comes
later in the process that begins with just what it is you propose to do,
what do you propose to spend, and whether you really like three-phase power
coming into your house.
Read the poop sheets again and see if your result is consistent across all
the 3s and 4s with comparable plate dissipation ratings and under comparable
operating conditions. Something ain't right.
Dick
w5lz
Look at the specs' again. Depending on the type of
amplifier your building (grounded grid, screen fed, grid fed),
'A', 'B', 'AB1', 'AB2', 'C', etc, you could choose either
of these two tubes. What are you going to do with the amplifier?
Just not enough information to make a choice...
'Doc
Hamm4fun
And the 4CX tetrodes are mostly grid driven.
phil
>Who can answer this question please, I was looking at the Eimac specs for
>various tubes and I noticed that between the 3CX nad 4CX there was a
>difference. The difference was in amplification factor, the 3CX had up to
>200 times amplification factor were is the 4CX only had 4.3
>The 4CX had more output watts but less amplification factor. Can someone
>explain this? and what's the better tube and why?
FWIW, the 4CX range seems to be gaining in popularity in both ham and CB
fields.
I chatted with Toll about this in Tyler.
It seems the 4CX's have more gain, thereby less drive for a given
output. That no doubt leads to less draw on the alternator/s!
Am I correct in that Bluegill currently runs a pair of tetrodes?
Phil / UK
phil
>Who can answer this question please, I was looking at the Eimac specs for
>various tubes and I noticed that between the 3CX nad 4CX there was a
>difference. The difference was in amplification factor, the 3CX had up to
>200 times amplification factor were is the 4CX only had 4.3
>The 4CX had more output watts but less amplification factor. Can someone
>explain this? and what's the better tube and why?
Further to my previous post I came across this on the Amps reflector and
thought it would be of interest:
The 3CX10,000A7 drives with 1500w.
The 4CX10,000A drives with 150w.
55 in Fla come in please, your time is up.
Phil / UK
Ter...@webtv.net
the 3CX the gain is for the whole tube.
Hello Phil, I enjoyed the chat in Texas
2-IR-082 Tim
>
>KRS,
>
>>Who can answer this question please, I was looking at the Eimac specs for
>>various tubes and I noticed that between the 3CX nad 4CX there was a
>>difference. The difference was in amplification factor, the 3CX had up to
>>200 times amplification factor were is the 4CX only had 4.3
>>The 4CX had more output watts but less amplification factor. Can someone
>>explain this? and what's the better tube and why?
>FWIW, the 4CX range seems to be gaining in popularity in both ham and CB
>fields.
>
>I chatted with Toll about this in Tyler.
>
>It seems the 4CX's have more gain, thereby less drive for a given
>output. That no doubt leads to less draw on the alternator/s!
>
>Am I correct in that Bluegill currently runs a pair of tetrodes?
>
>Phil / UK
>
>
>
>
>
>
Best Wishes And Good DX,
Tim 2-IR-082 Southern USA
Hottest and Most Current 11 Meter DX News:
HTTP://WWW.DXNEWS.DE
IRDX Main Site:
HTTP://WWW.IRDX.ORG
Most Complete Source of 11 Meter Links:
HTTP://WWW.DXZONE.COM
G SEVEN
So what is the preferred tube? Do you need 3 phase power to run 4CX tube?
KRS
<Ter...@webtv.net> wrote in message
news:2210-393...@storefull-224.iap.bryant.webtv.net...
phil
>hey phil, how was the trip to dayton and tyler for ya?
Dayton was rather too warm on the first day and due to being too tired I
missed out on a personal trip around WRW and Harris Broadcast.
Would of been nice to say, "I need to borrow one of them for a shoot-out
in Tyler;!
Tyler was OK, a good turnout and as Toll or Peak will tell you it was
only marred by a redneck getting out of hand one time.
I bought me a brand new Electrodyne E350-12 AC Powerhead which will be
shipped with other stuff to the Uk in July.
Bean, if you're listening, J & N in Cincinatti are deffinately the place
for alternators. Take your pick from new or rebuilt, Leece, Electrodyne
or Neihoff.
The Electrodyne was less than jobber and will eventually power my
3CX3000 once the Suburban comes out of the paint shop and I gather a few
more components.
55 out of Fla had a nice van with a second V8 in the rear powering 12
alternators.
Toll, Shadow and Peakaboo are now on my Christmas card list.
Was hoping to fly out again for Arkansas but am now bankrupt.
See ya
Phil / UK
--
phil
curio...@my-deja.com
phil <ph...@invest.fsbusiness.co.uk> wrote:
> KRS,
>
> >Who can answer this question please, I was looking at the Eimac
specs for
> >various tubes and I noticed that between the 3CX nad 4CX there was a
> >difference. The difference was in amplification factor, the 3CX had
up to
> >200 times amplification factor were is the 4CX only had 4.3
> >The 4CX had more output watts but less amplification factor. Can
someone
> >explain this? and what's the better tube and why?
and
> thought it would be of interest:
>
> The 3CX10,000A7 drives with 1500w.
>
> The 4CX10,000A drives with 150w.
>
> 55 in Fla come in please, your time is up.
>
> Phil / UK
>
phil did you enjoy your trip to the states?, did you find your
alternator that you were looking for? did you get mugged?,.......cd is
out........
Sent via Deja.com http://www.deja.com/
Before you buy.
curio...@my-deja.com
phil <ph...@invest.fsbusiness.co.uk> wrote:
> KRS,
>
> >Who can answer this question please, I was looking at the Eimac
specs for
> >various tubes and I noticed that between the 3CX nad 4CX there was a
> >difference. The difference was in amplification factor, the 3CX had
up to
> >200 times amplification factor were is the 4CX only had 4.3
> >The 4CX had more output watts but less amplification factor. Can
someone
> >explain this? and what's the better tube and why?
CB
> fields.
>
> I chatted with Toll about this in Tyler.
>
> It seems the 4CX's have more gain, thereby less drive for a given
> output. That no doubt leads to less draw on the alternator/s!
>
> Am I correct in that Bluegill currently runs a pair of tetrodes?
>
> Phil / UK
>
with all the rf that old man has absorbed over the years, it is
surprising that he is still with us, knock on wood, might have to
change his name to white gill before it is over,..cd is out...
Tim Kp82
mobile or base application.
Best Wishes And Good DX,
Tim Kp82 Knight Patrol USA
Hottest and Most Current 11 Meter DX News:
HTTP://WWW.DXNEWS.DE
Kp Main Site:
HTTP://WWW.GATE.NET/~KP
RocketMan
use it in. Yes you still need the 3 phase in a mobile how else will get the
A power...
"G SEVEN" <superiorw...@prodigy.net> wrote in message
news:8he532$2m4o$1...@newssvr03-int.news.prodigy.com...
Richard McCollum
"G SEVEN" <superiorw...@prodigy.net> wrote in message
news:8he532$2m4o$1...@newssvr03-int.news.prodigy.com...
>
> So what is the preferred tube? Do you need 3 phase power to run 4CX tube?
>
> KRS
You don't need three-phase as such but you do need one hell of a lot of DC.
I started broadcast engineering in my college days and my first transmitter
was a Gates 5kw FM transmitter using a 4CX5000 running about 5500 volts at
about 1.1 amps. The power supply (and this is steady carrier FM mind you)
had three-phase 480 volt primaries and a six pack of the old 866
mercury-vapor rectifiers glowing away.
The final and its hardware for tuning and coupling to the nitrogen-filled
coax was in a rack all by itself. The last time I looked, 5kw on 50 ohms
was about 10 rf amps which is not exactly what RadioScrap RG8 was designed
for.
I am a great fan of paper designing myself but do you have the slightest
idea what it takes to support one of these beasts? Just the tube -- not to
mention the associated socket, chimney, etc. -- will cost you enough. Now
build the power supply and the antenna structure complete with
positive-pressure gas coax (the gas truck will certainly interest the
neighbors). I am awaiting your plate tank design with great interest; do
you plan to drill holes in the floor for the 18 foot tuning strips, find a
tuning cap or two with 25kv insulation, or broadband it with the world's
largest matching transformer?
Oh, you are going to use it on SSB. Any good thoughts on where to find a
200 uf output filter cap with a 10 kv rating??? And the list goes on (and
on, and on). It is just a bit early in the game to be asking which is
'preferred'. I would personally use the tetrode in spite of having to
design something that would cut down the input if the screen supply
failed -- I don't like buying tubes for no good reason. Tetrodes are
generally easier to drive and are a lot less skittish than triodes but they
each have their place.
If I had the time and money to pull this caper off it would be 38th on my
list of six 'to-do's' today.
Dick
Tim Kp82
Best Wishes And Good DX,
Tim Kp82 Knight Patrol USA
Hottest and Most Current 11 Meter DX News:
Kp Main Site:
http://www.gate.net/~kp
Most Complete Source of 11 Meter Links:
Tim Kp82
which you seem to think is impossible. its in response to your last message.
****************************
I no longer have internet access, so please feel free to post this from
me...
This asshole deserves to be ripped on :)
> >>
> >> So what is the preferred tube? Do you need 3 phase power to run 4CX
tube?
> >>
> >> KRS
>>>Kris,
If you can get a good designer, the 4CX tubes are easier to drive in tetrode
configuration, and
the 4CX5K on up provide near or better than 20dB gain.. Meaning, I see
about 20Kw output
for 200 watts of input on my 4CX5000.
> >
> >You don't need three-phase as such but you do need one hell of a lot of
DC.
How the hell do you suppose your going to get the power? To get DC output
from
a AC source, you have to have a hell of a lot of AC input to the
transformer. This
comment alone proves that your nothing but a troll and a dolt... Or someone
who
prescribes to "old school" (read that as "I have been out of RF for so long
that I
have no idea what I am talking about" theories)
> >I started broadcast engineering in my college days and my first
transmitter
> >was a Gates 5kw FM transmitter using a 4CX5000 running about 5500 volts
at
> >about 1.1 amps.
So let's take a good look. Your running about 6Kw of input, and at 70
percent efficiency
(since the 4CX5K is only rated at 5Kw of diss. in class C, 6Kw class AB) you
see a little
more than 4Kw output. Pretty shitty for a tube that Eimac rates (and
Collins gets) 15Kw
in Class C FM.
> >The power supply (and this is steady carrier FM mind you)
Yes, steady carrier. Means that the power supply needs little to no
dynamic regulation. It is a static load on the transformer, filter cap and
associated power supply components.
> >had three-phase 480 volt primaries and a six pack of the old 866
> >mercury-vapor rectifiers glowing away.
How many primaries did it require?
Wait.. Look at this! You can get a pole pig transformer, run it in
reverse,
and get near 5500 VAC at 5+ amps! This just happens to be the same
transformer that the power company uses to drop the AC into your house!
Could it be? Yes, it COULD! You don't need 3 phase! And YES! The
power company CAN, AND DOES make 50 and 100 amp drops to radio
rooms for amateurs and CBers, as long as your willing to pay!
> >
> >The final and its hardware for tuning and coupling to the nitrogen-filled
> >coax was in a rack all by itself.
So, IOW, if we put it in plain text, that the average CBer would understand,
you
didn't use a Pi network? You used either stripline, or a cavity (probably
the cavity).
Since this is at 100++ megs, I would venture the cavity would be the proper
way to go.
Hey, guess what? I had a Collins 208U-10 10Kw PEP output (from a single
4CX10K
driven by a pair of 4CX250Fs, 200 mW in, 10Kw out) that was running on
220VAC single
phase... You gonna tell me Collins was a bunch of idiots now? DOubtful.
The last time I looked, 5kw on 50 ohms
> >was about 10 rf amps which is not exactly what RadioScrap RG8 was
designed
> >for.
> >
No, it isn't. However, I have run my 4CX5K with 150 watts of drive, and 5Kv
on the plate SSB
into rg-213. Hardline works even better. However, if using Hardline, you
need at least a small
run of 213 or LMR to the beam, for flexibility.
> >I am a great fan of paper designing myself but do you have the slightest
> >idea what it takes to support one of these beasts?
Yes. I build these amps. I don't do paper design. I do the actual
building of
both Class C and Class AB RF amplifiers.
Just the tube -- not to
> >mention the associated socket, chimney, etc. -- will cost you enough.
Tube app 400 dollars from Econco (rebuilt)
Socket app 300 dollars EBay (or TRW Swap-Fest, from where KRS lives :) )
Tranformer 600 dollars, if he chooses to get new from PWDahl.
Vacuum caps (2 needed) about 50 dollars a piece (E-Bay and TRW)
Plate tank coil 5 dollars (wound from copper ice maker tubing)
Filter cap for power supply less than a hundred bux.. Fair is having a sale
on 5Kv 33 mF caps.
The rest of the shit can be gotten from any ham user, or any high power
CBer.
Now
> >build the power supply and the antenna structure complete with
> >positive-pressure gas coax (the gas truck will certainly interest the
> >neighbors).
What the fuck are you talking about? Andrews Heliax or Hardline works fine,
and I have run a pair
of 4CX15000s into them (well, set the system up). This was at over 50Kw AVG
power out, 100Kw ++ PEP.
Ran off (you guess it!) 44 3phase in a commercial environment.
Once again, your showing your age, mi amigo.
I am awaiting your plate tank design with great interest; do
> >you plan to drill holes in the floor for the 18 foot tuning strips,
At HF, we don't use stripline, moron. At HF you would use a 10 to 400 Pf 10
Kv Jennings vacuum cap,
a 25Kv 1000pF blocking cap, about 5 turns of 3/8 to 1/2" diameter tubing for
the plate circuit and a 100 to 1000
5Kv ant tune jennings.
find a
> >tuning cap or two with 25kv insulation,
Not needed if you use a good plate blocking cap.
or broadband it with the world's
> >largest matching transformer?
That is commonly done with Aphas and Command Technologies amateur legal
limit amps, to
get good 80 and 160 coverage at 2500 watts. They use large core stock.
> >
> >Oh, you are going to use it on SSB. Any good thoughts on where to find a
> >200 uf output filter cap with a 10 kv rating???
What? At 5 amps, you need more like 30 to 60 uF at 9kV. WAY less if you
use choke
input.
And the list goes on (and
> >on, and on).
Nope. I can build a RF deck for about a thousand dollars, if I look hard
enough.
If the CBer wants to drive the piss out of it, I still use a tetrode, but
connect the grid and
screen together, and let them drive the cathode / filament. This give one
HELL of a triode,
and results in 18 grand out of a 4CX5K on a stiff base power supply.
It is just a bit early in the game to be asking which is
> >'preferred'. I would personally use the tetrode in spite of having to
> >design something that would cut down the input if the screen supply
> >failed --
>>>Why? Use a small transformer that has a core that saturates at 10
percent greater current
draw than design. This limits screen current in the event of plate power
supply failure. Ditto for the fils
transformer. No more inrush current resistors are needed then.
I don't like buying tubes for no good reason. Tetrodes are
> >generally easier to drive
Yes, your right.
> >and are a lot less skittish than triodes
That is pure bullshit. A tetrode (by the nature of the beast) is harder to
tame than a triode, due to
the higher gain at VHF and above. Almost all tetrodes require
neutralization, and VHF suppression
in both the anode and grid department. Triodes never have the amount of
gain for same-dissipation
figures. Especially at VHF. Your comment was TOTALLY off.
I hope your old professor doesn't read this group.. He would be dying of
laughter.
> >but they
> >each have their place.
> >
> >If I had the time and money to pull this caper off it would be 38th on my
> >list of six 'to-do's' today.
> >
Time, app one week, start to finish
Money? Like I said.. About a grand, if you spend the time and look
carefully.
Have a good one!
--Toll Free, via Tim in Texas!
*****************************
Professor
"Tim Kp82" <tim...@aol.common> wrote in message
news:20000605161908...@ng-cp1.aol.com...
RocketMan
the answer to that would be yes.
"Richard McCollum" <rmc...@radiks.net> wrote in message
news:vIP_4.3582$EU3....@newsfeed.slurp.net...
> > KRS
>
> You don't need three-phase as such but you do need one hell of a lot of
DC.
> The final and its hardware for tuning and coupling to the nitrogen-filled
> coax was in a rack all by itself. The last time I looked, 5kw on 50 ohms
> was about 10 rf amps which is not exactly what RadioScrap RG8 was designed
> for.
========================================================================
For intermittent use rg-217 would work fine but I would use rg-218 for any
lengthy qso's ...
I am awaiting your plate tank design with great interest; do
> you plan to drill holes in the floor for the 18 foot tuning strips, find a
> tuning cap or two with 25kv insulation, or broadband it with the world's
> largest matching transformer?
-----------------=======================================================
What band are you using 18' tuning strips on certainly not 11 meters
>
> Oh, you are going to use it on SSB. Any good thoughts on where to find a
> 200 uf output filter cap with a 10 kv rating???
----------------------------------------------------------------------------
--------------------------------------------------
Ahh...ever heard of Jennings? Plenty of surplus caps available....On
ebay,ham ng...
>
> If I had the time and money to pull this caper off it would be 38th on my
> list of six 'to-do's' today.
----------------------------------------------------------------------------
--------------------------------------------------
I have pulled this caper off in a mobile...3cx6000...It is not cheap, If
done right but 10kw+ watts are never.
>
> Dick
>
>
Bill Eitner
All the good guys are gone. I don't know why
I even come out here anymore. The "golden age"
of this newsgroup has come and gone.
--
-------------------------------------------------------------------
-=[Bill Eitner]=-
Link to A.M. Tutorial, rec.radio.cb FAQ
and The Dark Side:
http://kd6tas.conk.com
-------------------------------------------------------------------
Tim Kp82
Richard McCollum
than looking at an EiMac poop sheet. I have no disagreement with a word the
man says; if fact it makes my point. For the record, he is absolutely
correct about the shunt fed final done in the manner he suggests. He may,
however, be better served by friends who let him see the whole thread. He is
hereby nominated as the King Kong of Tubes.
To clarify a point that I did not make very well, it is common in commercial
service to keep tubes to their plate dissipation ratings along with a host
of other things to prevent total failure. In the broadcast business, being
off the air is at best expensive and can ultimately draw the nice man from
FCC, less so of recent years but certainly so in the big days of tubes.
General Electric in their VHF repeaters (law enforcement only) put their
finals in a big block of machined aluminum to play heat sink and built two
375 volt supplies, cascaded to cut the plate voltage in the event of screen
supply failure. I have no doubt that the three phase supply of the FM
transmitter was more a case of having one or two working when the local
power company dropped one leg. The point is simply that design follows
mission; hobbyists can, do, and should stretch things out a tad. Before
asking what is 'desirable', it is a great idea to know just what it is that
is being done. Whatever else it may be, a 4CX-big number is not a
beginner's project.
We might have some interesting discussion about power supply design for
linear and particularly SSB service. For a prime example of lack of
attention to it, WGTG's sideband transmitter is a great place to begin if
you can hear them at all.
The only real difference we have is philosophical. If it don't get you
paid, laid, or fed it is pretty hard to get interested. There indeed I am
showing my age.
Dick
"Tim Kp82" <tim...@aol.common> wrote in message
news:20000605174639...@ng-cp1.aol.com...