[Boatanchors] Boatanchors Digest, Vol 187, Issue 13

Sun Aug 18 10:26:29 EDT 2019

 Gary and the group.The 837 does not have beam forming plates but has a suppressor grid. It was used in the GF-11 navy aircraft transmitters.It is a good tube for GG linears, also for suppressor grid modulated transmitters.The GF-11 was the first military transmitters I used on the air; no mods were needed in the little transmitter, just as adequate power supply, a correct plug and a carbon mike! (And a good antenna)
73 and thanks,John Allen, W4GQT since 1959
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    On Friday, August 16, 2019, 1:37:47 PM EDT, boatanchors-request at mailman.qth.net <boatanchors-request at mailman.qth.net> wrote:  

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Today's Topics:

  1. Re: P&H LA-400 linear (Bill Henderson)
  2. Re: P&H LA-400 linear (Ron VE8RT)
  3. Re: P&H LA-400 linear (Ian Wilson)
  4. Re: P&H LA-400 linear (Gary Schafer)

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Message: 1
Date: Fri, 16 Aug 2019 08:11:49 -0400
From: Bill Henderson <bill.henderson at ocdsb.ca>
To: Ron VE8RT <ve8rt at yknwt.ca>
Cc: Boatanchor group <boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] P&H LA-400 linear
Message-ID:
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You may want to keep an eye on:

http://www.kwarc.org/swapshop/

 - Bill H. / va3hwa

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On Thu, Aug 15, 2019 at 9:53 PM Ron VE8RT <ve8rt at yknwt.ca> wrote:

> Hi Bill,
>
>    the last hamvention I attended was in 2011, when the XYL VE8LT
> accompanied me to SeaPac in Oregon.  I picked up my K2/10 and a few other
> items while there.  Tube sockets were hard to find, I remember that.
> When someone asked me if we'd be back next year I told them that we
> could re-equip the station with new gear for the cost of that trip, I
> didn't think so.  Yeah, there isn't much in the neighbourhood, maybe in
> Edmonton (2 day drive each way).
>
>    Shipping costs within Canada are of course lower than getting
> things out of the US, when I can find what I'm looking for.
>
>    I'm not in a hurry, buying or building an amplifier has been on my
> list of items I'd like to have for a few years.
>
>    73  Ron VE8RT
>
> On Thu, 15 Aug 2019 08:36:17 -0400
> Bill Henderson <bill.henderson at ocdsb.ca> wrote:
>
> > Hi Ron....
> >
> > I guess there aren't a lot of hamfests in Yellowknife (VE8) area...
> > but that would be one of the places I would check.
> >
> > Don't rule out buying from within Canada  - still shipping costs but
> might
> > not be as much.
> >
> > Also might want to checkout:
> >
> > https://www.qsl.net/n6ev/4x807.gif
> >
> > and
> >
> >  https://www.qsl.net/n6ev/4x807_ps.gif
> >
> > (the power supply)
> >
> > http://www.w7ekb.com/glowbugs/projects/JunkerAmp.pdf
> >
> > https://www.eham.net/ehamforum/smf/index.php?topic=78547.0;wap2
> >
> > The Junker amp is my "go to" for such - relatively simple,
> straightforward,
> > worth a read at least.
> >
> > 73 de va3hwa / Bill H.
> >
> >
> >
> >
> >
> > [image: Mailtrack]
> > <
> https://mailtrack.io?utm_source=gmail&utm_medium=signature&utm_campaign=signaturevirality5&
> >
> > Sender
> > notified by
> > Mailtrack
> > <
> https://mailtrack.io?utm_source=gmail&utm_medium=signature&utm_campaign=signaturevirality5&
> >
> > 08/15/19,
> > 08:32:58 AM
> >
> > On Thu, Aug 15, 2019 at 7:45 AM Ron VE8RT <ve8rt at yknwt.ca> wrote:
> >
> > > GM Howard,
> > >
> > >    a problem with projects here is paying the S&H charges on many small
> > > orders to get them to Canada.  It would work out cheaper to see if I
> > > couldfind one repairable or intact boatanchor to use for parts or to
> > > repair and get the shipping over in one larger payment.  It recently
> > > came up when I was looking to buy something from RF parts and the
> > > minimum charge for S&H on international orders was $20.  So if I had to
> > > get a variety of bits from a few different places it starts to get
> > > expensive.
> > >
> > >    Ron VE8RT
> > >
> > > On Thu, 15 Aug 2019 04:50:29 +0000
> > > howard holden <holden7471 at msn.com> wrote:
> > >
> > > > Probably easier to build one than buy a 1625 (or 807) amp. For
> instance,
> > > > the Feb 1975 QST has one with 4 807s in an article titled
> "Transmitting
> > > > Variables". Socket/wiring changes to accommodate the 1625 a breeze.
> > > > Pretty easy to get that genre of tubes - 807, 1625, 6BG6 etc. -
> going.
> > > >
> > > >
> > > > 73, Howie WB2AWQ
> > > >
> > > > On 8/14/2019 5:49 PM, Ron VE8RT wrote:
> > > > >    I'm giving some thought to having a linear amp available (I'm
> > > > > comfortable with low power most of the time).  In my collection of
> old
> > > > > tubes are a single 811, a pair of 813s, a 4CX250, some 6146s and
> > > > > variants, and a few 1625s.  It may not be the only amplifier, but I
> > > found
> > > > > that the P&H LA-400 (early models) used the 1625s.  How difficult
> would
> > > > > it be to find a 1625 based amplifier?
> > > > >
> > > > >        Ron VE8RT
> > > > ______________________________________________________________
> > > > Boatanchors mailing list
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> > > > List Administrator: Gary Harmon, K5JWK
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> > > >
> > > >
> > > > This list hosted by: http://www.qsl.net
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> > > > Message delivered to ve8rt at yknwt.ca
> > >
> > > --
> > > Ron VE8RT <ve8rt at yknwt.ca>
> > > ______________________________________________________________
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> > >
> > > List Administrator: Gary Harmon, K5JWK
> > > ** For Assistance: gharmon at idworld.net **
> > >
> > >
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> >
> > --
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>
> --
> Ron VE8RT <ve8rt at yknwt.ca>
>

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Message: 2
Date: Fri, 16 Aug 2019 06:15:42 -0600
From: Ron VE8RT <ve8rt at yknwt.ca>
To: Rob Atkinson <ranchorobbo at gmail.com>
Cc: Boat Anchors List <boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] P&H LA-400 linear
Message-ID: <20190816061542.0b1616dd3620a813fdf07c0c at yknwt.ca>
Content-Type: text/plain; charset=US-ASCII

I'll check.  Hopefully if I did take on a HB project like this Icould
get a little technical assistance from the group when needed.

Must get out the door for work, have another year before I might be
able to retire.

  Ron

On Fri, 16 Aug 2019 06:45:40 -0500
Rob Atkinson <ranchorobbo at gmail.com> wrote:

> I think there are often a lot of 4-65As on eBay and the socket is used
> by a few tubes.  Fair Radio sold 4D32s--it might use the same socket;
> can't remember for sure.  What's nice about the 4-65A is that you can
> put a lot more Ep on the anode.  4-65s are cheap usually because
> demand is low.
> 
> 73
> Rob
> K5UJ
> 
> On Fri, Aug 16, 2019 at 6:38 AM Ron VE8RT <ve8rt at yknwt.ca> wrote:
> >
> > They're not tubes i have on hand, but I'm open to recommendations.  I
> > can see the four 807s wouldn't be that efficient, unless the point was
> > to heat the shack, at over thirty cents per kilowatt hour for our
> > electricity their are cheaper ways to do that.

-- 
Ron VE8RT <ve8rt at yknwt.ca>

------------------------------

Message: 3
Date: Fri, 16 Aug 2019 07:05:12 -0700
From: Ian Wilson <ianmwilson73 at gmail.com>
To: Rob Atkinson <ranchorobbo at gmail.com>
Cc: Boat Anchors List <boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] P&H LA-400 linear
Message-ID:
    <CAEz8jcS4XSX1iEk+43zLzM=Y92=x9eVSJYHUPuKDZ1KwRWkb-g at mail.gmail.com>
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I have seen a number of 4-65A's that have become gassy. Possibly this was
one of
Eimac's earlier attempts at the type of pin/glass seal? Obviously this is a
small sample
but out of perhaps 20 4-65A's I have seen 4 or more that were gassy.

On the other hand, have never seen a problem with 4D32/4D22 - these have a
satisfying 'like a brick' feeling.

73, ian K3IMW

On Fri, Aug 16, 2019 at 4:21 AM Rob Atkinson <ranchorobbo at gmail.com> wrote:

> GG usually takes more drive power for a given output power.  The
> schematic someone posted was 807s grid driven.  It was a complicated
> looking design compared to a cathode driven g.g. triode, but I assumed
> the point to it was to have a high gain 100 w. amp that could be
> driven by a dinky QRP rig.  If I were doing this and wanted such an
> amp I'd go with a single 4-65A or 4D32 and forget about a lot of 807s.
> If I were looking at cathode driven I'd try a single 812 or maybe
> 572B.
>
> Rob
> K5UJ
>
> On Fri, Aug 16, 2019 at 2:35 AM <hwhall at compuserve.com> wrote:
> >
> > Advantages of grounded grid, if I recall correctly, included not needing
> neutralization, and driver power not needed for drive was passed thru to
> the output.  IIRC.
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------------------------------

Message: 4
Date: Fri, 16 Aug 2019 12:36:22 -0500
From: "Gary Schafer" <garyschafer at largeriver.net>
To: "'Robert Downs'" <wa5cab at cs.com>,    <boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] P&H LA-400 linear
Message-ID: <1658E7966FBA4EF3A9CACC9EAA48F9D1 at garyPC>
Content-Type: text/plain;    charset="us-ascii"

The 837 has a separate beam forming lead on one pin so it can be grounded.
They worked pretty good in gg.

Some 1625's the beam forming plates came thru the glass with a separate wire
and both the cathode wire and beam forming wire went into a single pin on
the base. Some guys used to use a solvent to loosen the glue between the
phenolic base and the glass envelope. You then had to desolder all of the
pins and remove the base. You could then separate the beam forming lead from
the cathode and put it into an unused pin in the base. 
Another way (easier to me) was to cut a slot part way around the base near
the bottom and you could fish out the beam forming lead and place it into an
unused base pin. Like doing micro surgery.
I have done many of those lots of years ago.

None of the RCA brand tubes could be modified as the beam forming and
cathode were tied together inside the glass.
National Union was one brand that I remember could always be modified. Some
of the other brands could and some could not be modified.

If you look carefully at the bottom of the glass where the leads go thru you
can visually trace the beam forming leads and the cathode leads thru the
glass. If you see two separate leads then the tube can probably be modified.
Most often on tubes that couldn't be modified you could see a strap welded
between the leads before they went to the bottom of the glass and there
would only be one wire going thru the glass for both elements.

None of the 807 tubes were ever made with separate leads on the beam forming
plates. They were always connected to the cathode internally so they would
not work in gg.

I think the OP was looking for an amp for his 20A. The 1625's will work but
the 20A is short on drive for them. If you get 100 watts out of 4 of them
you are doing good and that requires near 1000 volts on the plates.

I used to use a pair of 6ag7's in gg driving some 1625's with my 20A.
Simple circuit and stable.

73
Gary  K4FMX

> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-
> bounces at mailman.qth.net] On Behalf Of Robert Downs via Boatanchors
> Sent: Friday, August 16, 2019 2:19 AM
> To: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] P&H LA-400 linear
> 
> One subject that I don't recall being mentioned in this thread but that
> has
> been in almost every similar thread in the past is that some if not most
> of
> these 200 watt nominal linears using four 807's or four 1625's are wired
> as
> grounded grid amps.  And that the beam forming plates inside the tubes
> that
> must be grounded are electrically connected to the cathode, not brought
> out
> to a separate pin.  So stock tubes apparently won't work but must be
> modified.  I never paid that much attention to the threads but seems
> like at
> this point most threads split off into which brands of tubes could be
> modified and which couldn't.  Some 1625's apparently had the cathode and
> beam forming plates electrically connected inside of the tube envelope
> and
> cannot be modified.  Some had the connection made inside of the tube
> bases
> and can be.  I've long ago forgotten which brands could and which
> couldn't.
> And why the grounded grid configuration was preferred over the
> conventional
> grounded cathode.
> 
> Robert Downs
> 
> 
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End of Boatanchors Digest, Vol 187, Issue 13
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