Im building a HF linear using four PL519's. Can i use 2oz copper PCB for the
base to fit the valves too?????? as Im not very good at cutting and messing
with metal.


--



Thanks and 73's de Paul M0EME
432MHz EME 4 times FO19,
FT847,
MGF1302,
100 Watts at feed,
Spectran.
Initials 432MHz #2 CW #4 JT65

http://myweb.tiscali.co.uk/m0eme

Paul M0EME wrote:
Im building a HF linear using four PL519's. Can i use 2oz copper PCB for the
base to fit the valves too?????? as Im not very good at cutting and messing
with metal.


--


Hi Paul,
you can - but not recommended. Valves generate a lot of heat, and PCB
is not good at dissipating it - would have problems very soon. Why not
use aluminium sheet - easy to work as PCB, - I get mine form a local
scrap merchant, they have pieces big enuff to build any chassis I want,
and its a lot stronger AND cheaper than pcb.

73 de VK3BFA Andrew.

Im building a HF linear using four PL519's. Can i use 2oz copper PCB for the
base to fit the valves too?????? as Im not very good at cutting and messing
with metal.
=====================
Of course you can use (preferably double sided ) PCB , also for
enclosures .

Good luck with your project

Frank KN6WH / GM0CSZ

Andrew VK3BFA wrote:

Paul M0EME wrote:
Im building a HF linear using four PL519's. Can i use 2oz copper PCB for the
base to fit the valves too?????? as Im not very good at cutting and messing
with metal.


--


Hi Paul,
you can - but not recommended. Valves generate a lot of heat, and PCB
is not good at dissipating it - would have problems very soon.

...while others say "Go ahead".

For this application I'd agree with Andrew - the PC board is going to
get HOT! I discovered this a long time ago, with a little VHF
transverter that created much less than a tenth of the heat that a
300-400W PA will. Until then, I'd never appreciated how much we rely on
an ordinary aluminium chassis to dissipate heat from the valve bases, or
how well it does it.

Unless you use a blower is actively aiming to cool the board as well as
the valves, the fibreglass is going to stew, turn brown and warp.

Why not
use aluminium sheet - easy to work as PCB, - I get mine form a local
scrap merchant, they have pieces big enuff to build any chassis I want,
and its a lot stronger AND cheaper than pcb.

That's basically true, but it just takes longer, and I don't suppose
Paul will have all the metalworking tools we OFs have collected over the
years. The main point is to make sure you get *soft* aluminium, and also
try to get it cut to size. Or try to find some old radio gear that was
built with a chassis and cabinet, and rebuild inside that... another
honourable tradition.

There was once an SP station who soldered the bases of *ten* 807s on a
sheet of PC board for his HF amp. But that was in another century, in a
desperate country before the Wall came down. It can be done, but it
isn't a good example to follow.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian White GM3SEK wrote:
Andrew VK3BFA wrote:


Why not
use aluminium sheet - easy to work as PCB, - I get mine form a local
scrap merchant, they have pieces big enuff to build any chassis I want,
and its a lot stronger AND cheaper than pcb.

That's basically true, but it just takes longer, and I don't suppose
Paul will have all the metalworking tools we OFs have collected over the
years. The main point is to make sure you get *soft* aluminium, and also
try to get it cut to size. Or try to find some old radio gear that was
built with a chassis and cabinet, and rebuild inside that... another
honourable tradition.


I would humbly disagree with this - aluminium is fairly easy to work. A
metal cutting blade in your jigsaw, a set of drill bits, hole cutting
saws are now very cheap (you dont need super HSS ones for soft
aluminium, a rat tail file .. pretty basic tools...the stuff you need
to work PCB into shape!

bending is a problem, I must admit - one day, will make a sheet metal
bender - in the meantime, bits of angle iron clamped in a vise give
reasonable results......

More fundamentally - why use PL519's - arent they TV sweep tubes, like
6JS6's - a poor choice in this day and age, unless you have a box of
them cheap (plus the sockets...) Proper transmitting tubes are
available at a reasonable price - even the humble old ones like 811A's
would be a better choice!

de VK3BFA Andrew.

: Paul M0EME wrote:
: Im building a HF linear using four PL519's. Can i use 2oz
: copper PCB for the base to fit the valves too?????? as
: Im not very good at cutting and messing with metal.
: Thanks and 73's de Paul M0EME

Hi Paul,

The work has already been done for you. Simply buy the
Replacement Dentron GLA-1000 conversion to the el-509/519
PC Boards cheap from FAR Circuits.

If you keep air moving in the chassis, you should not
have any problems. Sockets are available from a place
in Florida selling on line.

You might also consider joining the yahoo rfamplifiers
group.

http://groups.yahoo.com/group/rfamplifiers/

cheers,
skipp

Im building a HF linear using four PL519's. Can i use 2oz copper PCB for
the base to fit the valves too?????? as Im not very good at cutting and
messing with metal.
====================
Don't understand what you mean with '2 oz copper PCB' ,but any fibreglass
single or double sided PCB would be suitable , provided you don't put heavy
stuff on it like PS transformers etc. If double sided make sure both sides
make good galvanic contact at various locations.
I also like using PCB for (not too large) chassis and enclosures. Same
material screens can be readily soldered-in. Another advantage is that where
necessary components can be bonded to ground (chassis) directly.

Frank GM0CSZ / KN6WH

Highland Ham wrote:

make sure both sides make good galvanic contact at various locations.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

"Galvanic contact"? Are you trying to generate electricity or
electrocute someone?

1. Go to dictionary.
2. Look up "galvanic".
3. Don't do it.

Bill, W6WRT