Dick,
Thanks for letting me know. Evidentally, some on the net are confused about the
tube numbers as per the Google searches I done. When doing one for a GU-84B,
the very first listing was saying GU-84B/4CX1600B as was several others. I then
noticed others saying it was a 4CX2500 and Emtron saying it had a 2500 watt
disapation after lookin further. The one listing mentioned that the GU84B was a
militarized version of a 4CX1600 which evidentally aint so. I went and looked
at some pics and there is some clear differences. plus, the 4CX1600B was
supposed to of been discontinued by Svetlana. Others I seen mentioned using the
GU-84B as a good replacement for the 4CX1600, so others may have mis-understood
this and figured they were the same, I dont know. I'm still looking to see if I
can find where I read about the tube and about the extra cooling. I was at some
Russian websites the other day and I think it was there where I read that. That
was when I was wanting the Russian translation
for part numbers for a screen/bias supply I had seen. Finding the original
posting of that though might take some time as remembering which and where is
going to take some doing as I didn't bookmark anything. I always figure it's
better to tell anything like that when you find it so others wont spend a lot
of bux and not have what they want in the end. Of course from this, what they
had written about it could be completely wrong by them refering to two
different tubes and saying they were the same! Thanks again for this post with
the specs.
Best,
Will
>
> Some info from: http://www.angelfire.com/nb/ni4l/gu84b.html
>
> The GU-84B is a ceramic-metal forced-air cooled tetrode intended
> for use in power amplifiers with distributed amplification and for
> SSB-signal amplification with output power up to 2.5 kW at
> frequencies up to 75 MHz as well as for power amplification at
> frequencies up to 250 MHz with output power up to 2.2 kW in
> radiotechnical equipment. The Svetlana 4CX2500/GU-84B is
> manufactured in the Svetlana factory in St. Petersburg, Russia.
> GU-84b is the military version of the Svetlana tetrodes.Typical use
> would be transmitters "PLAMYA" ("FLAME"-eng.),used on submarines.In
> emergency mode GU-84B can work without cooling aproximately 20-30
> minutes.Many amateur radio stations see 4 KW in SSB and CW modes.
> They use GU-84B in long-lasting contests.
>
> Cheers, Dick
>
>
> ----- Original Message ----- From: "Will Matney" <craxd@engineer.com>
> To: <Amps@contesting.com>
> Sent: Wednesday, July 20, 2005 2:33 PM
> Subject: Re: [Amps] GU-84B Cooling
>
>
> >
> > Gerald,
> >
> > Yea, as long as it runs within the ratings, it'd be ok. That makes
> > one wonder if Eimac might have made an over-kill on the radiator of
> > the 4CX1500. I'd have to see what Eimacs temp specs are for it as
> > compared to the GU-84B, plus there's a 100 watt dissapation
> > difference there too. I wonder if the guts in the GU-84B are maybe
> > beefier than the ones in the 4CX1500? What I'd read is they were
> > almost identical except for the radiator size. If the GU-84B runs
> > as cool as the 4CX1500 with the same cooling arrangement, that
> > would tell the tail. But, if it ran hotter, I'd say it would sure
> > need more air to operate the same. I'll try my best to find that
> > article where I read about the differences if I can and post it
> > here. It's was a while back so I may not be able to find it on the
> > net.
> >
> > Best,
> >
> > Will
> >
> >
> > ----- Original Message -----
> > From: TexasRF@aol.com
> > To: craxd@engineer.com, Amps@contesting.com
> > Subject: Re: [Amps] GU-84B Cooling
> > Date: Wed, 20 Jul 2005 07:56:21 EDT
> >
> >>
> >> In a message dated 7/20/2005 3:13:43 A.M. Central Standard Time,
> >> craxd@engineer.com writes:
> >>
> >> Dick,
> >>
> >> I'm not saying it's a bad tube, and dont want none to think that. I just
> >> dont want anyone to undercool the tube so it will last. Who
> >> knows, the 4CX1500
> >> may have an over-sized radiator too! About the only way to tell
> >> about the temp
> >> would be to use a thermocouple connected to the anode. Then the temp read
> >> under contesting conditions both under SSB and AM using the air flow they
> >> recommend. AM/CW creates a good bit more load on one as does SSB
> >> transmissions.
> >> Then if the temp stays down where it should, one would know it
> >> would be ok. I'm
> >> like Rich, and what George mentioned, use the largest blower possible.
> >> Another thing too is maybe mount and external blower and duct it
> >> to the amp. You
> >> can set one of these in another room to help kill the sound down if it's a
> >> concern. On yours, you may have the right combination by using
> >> enough fans both
> >> pushing and pulling. Have you measured what the air flow and pressure is
> >> on
> >> your amp? If so, let us know so we all have a starting point.
> >>
> >> Best,
> >>
> >> Will
> >>
> >>
> >>
> >>
> >>
> >> GU84B data at the ND2X website shows 57 cu ft per minute air flow at 1.2"
> >> back pressure. There are Dayton blowers readily available from
> >> Grainger Supply
> >> that will do this.
> >>
> >> Running the tube at 3000v, 1.7A , class AB1, locked key, would generate a
> >> heat load of about 1900 watts.
> >>
> >> Using the heat rise equation from the ARRL Microwave/UHF Experiments
> >> manual,
> >> room temperature into the tube would exit at about 190 degrees F (88
> >> degrees
> >> C).
> >>
> >> This sounds like a reasonable scenario doesn't it? AM linear operation will
> >> back the dissipation way down as would cw or ssb.
> >>
> >> Doesn't seem even that multiple blowers would be neeeded.
> >>
> >> 73,
> >> Gerald K5GW
> >
> >
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