[Hallicrafters] PL-172's

[Roger (K8RI)]

On 11/11/2010 7:26 PM, Carl wrote:
> Different amp, different tubes.
The HT-33 used the 4CX300 while the HT-33A and HT-33B both use the 
PL172/8295A  Pentode, which is a bit misleading as they both use the 
glass sealed version. However the 8295A is electrically the same as the 
PL172/8295A, but mechanically it uses a ceramic to metal seal that is 
about a half inch high which makes it about 3/8" taller than the 
PL172/8295A with the glass to metal seal.  The tubes are directly 
interchangeable in the two amplifiers with no modification.

These two tubes are substantially larger than an 8877, but are only 
rated at 1 KW plate dissipation.  The anode has heavier fins with larger 
spacing which means they require little back pressure and can be cooled 
with a small fan.

If good they can be worth as much, or more than the amp.  The 8295A goes 
for about twice  the PL172/8295A.  When RF Parts had them about a year 
ago they were getting $1200 and $2400 respectively for *guaranteed* good 
tubes.  Last I checked typical prices are in the $100 to $400 range.

It's rare to find a PL172/8295A that isn't gassy from just sitting 
around.  These are one tube that should be swapped out regularly and not 
left to set on a shelf.

73

Roger (K8RI)
>
> ----- Original Message -----
> From: "Jon Springer"<springertool at wyoming.com>
> To: "'Brian Harris'"<cosmophone at yahoo.com>
> Cc:<hallicrafters at mailman.qth.net>
> Sent: Thursday, November 11, 2010 7:16 PM
> Subject: Re: [Hallicrafters] PL-172's
>
>
> Hi, Brian ... I am fixing to start firing up an HT-33A ... need to
> investigate the leaking oil under it first... would be glad to work with u
> in the near future.  I'm sure I will be needing a spare PL-172.  Incidently,
> I read about these tubes recently: that the glass ones are leakers, but, the
> ceramic ones are much better ... don't have any experience with them myself.
>
> Regards,  Jon KØFOP
> 307 857 3069
> Riverton, Wyoming
>
>
>
> -----Original Message-----
> From: hallicrafters-bounces at mailman.qth.net
> [mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Brian Harris
> Sent: Thursday, November 11, 2010 3:34 PM
> To: Hallicrafters; Boat Anchors
> Subject: [Hallicrafters] PL-172's
>
> Today I acquired three PL-172's and one PL-172 socket.  One tube has a glass
>
> seal.  The other two have ceramic seals and are also marked 8295.  All are
> made
> by Penta.  One of the 8295's looks as if it's new.  The other looks very
> good
> (with very little discoloration).  The one with the glass seal has been used
> as
> there uniform discoloration (but no black).  These came from a SK who had
> them
> as spares for his amplifier which is long gone.
>
> I would like to either sell these tubes and the socket (preferred) or build
> an
> amplifier (not preferred) but I need to know if they are any good.  As I
> have no
> way to test them, I am looking for someone who has an HT-33B that would be
> willing to test them.  It would be great if that person lived close to the
> Dallas-Ft.Worth area.
>
> If someone can test them for me I will give them the glass sealed tube
> provided
> it's good or some quickly diminishing in value U.S. dollars for their
> services.
>
> Please don't make me make a test jig.
>
> Brian Harris, WA5UEK
> phone 214-763-5977
> email cosmophone at yahoo.com
> website www.myhamshack.com/wa5uek
>
>
> When they call the roll in the Senate, the Senators do not know whether to
> answer "present" or "not guilty."  Theodore Roosevelt
>
>
>
>
> ______________________________________________________________
> Hallicrafters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Hallicrafters at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Hallicrafters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Hallicrafters at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Hallicrafters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Hallicrafters at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>