Hi all,

I recently became interested in trying to build a small two-tube regen type
receiver for broadcast and/or shortwave reception. I designed a simple
chassis based on some vintage articles on the subject. This is the classic
'metal box with attched front faceplate' design. I was going to use
cold-rolled steel since we have this at work and spot weld the face to the
main chassis, but then I got to thinking that perhaps the steel might
interfere with the coils. I noticed also after this that every old article
that I've come across usually suggested aluminum for the chassis. They
don't make mention of the reasons for this, however. I was wondering if
ease of machinability for the amatuer working with simple hand tools, and
perhaps also weight savings, were main factors, or was it mainly for lack of
magnetic interation with the coils? We also have sheets of aluminum, brass,
and stainless that I can use but I'm not sure if they can be resistance
welded, so I would have to bolt the face onto the main chassis box. Anyone
have any further ideas or insights?

thanks in advance,

Dave

David Forsyth wrote:
Hi all,

I recently became interested in trying to build a small two-tube regen type
receiver for broadcast and/or shortwave reception. I designed a simple
chassis based on some vintage articles on the subject. This is the classic
'metal box with attched front faceplate' design. I was going to use
cold-rolled steel since we have this at work and spot weld the face to the
main chassis, but then I got to thinking that perhaps the steel might
interfere with the coils. I noticed also after this that every old article
that I've come across usually suggested aluminum for the chassis. They
don't make mention of the reasons for this, however. I was wondering if
ease of machinability for the amatuer working with simple hand tools, and
perhaps also weight savings, were main factors, or was it mainly for lack of
magnetic interation with the coils? We also have sheets of aluminum, brass,
and stainless that I can use but I'm not sure if they can be resistance
welded, so I would have to bolt the face onto the main chassis box. Anyone
have any further ideas or insights?

thanks in advance,

Dave


Steel will be fine. Your suspicions about workability are correct but
there is also plating/painting to consider.
-Bill

Only one problem I ever had with a steel chassis was a project that
used a rather sizable power transformer. The transformer induced
currents into the steel chassis that caused metering problems. It was
corrected by using a single-point ground to the chassis.

Steel chassis were the norm for much of the tube years, commercial and
amateur.

Only one problem I ever had with a steel chassis was a project that
used a rather sizable power transformer. The transformer induced
currents into the steel chassis that caused metering problems. It was
corrected by using a single-point ground to the chassis.

Steel chassis were the norm for much of the tube years, commercial and
amateur.

Yes, I have found when building regenerative receivers wood is the best
chassi. However a metal front panel is a must. However I only use battery
tubes with low voltage. Never more than 45 volts. But when building
solid-state regeneratives. A good ground plane helps. Build it the dead
bug way.

The "dead bug" way? I'm not sure what this means - please forgive me I'm
new to this :-)


Dave



"Bill Hennessy" wrote in message
. ..
Yes, I have found when building regenerative receivers wood is the best
chassi. However a metal front panel is a must. However I only use
battery
tubes with low voltage. Never more than 45 volts. But when building
solid-state regeneratives. A good ground plane helps. Build it the dead
bug way.

David Forsyth wrote:
The "dead bug" way? I'm not sure what this means - please forgive me I'm
new to this :-)

Hehe, don't feel too bad. I have zero experience with solid state stuff,
so when I was told to build my trial projects in DBSF format, I was left
scratching my head. I laughed out loud when I was shown a "Dead Bug
Squashed Flat" project. This is your components laid out flat on a
perfboard and the wires run straight, point to point. It really does
look like a DBSF!!

I'm not sure how to do the tubes in a DB format, but everything else
should be straightforward.

"General Radio" used to sell tube sockets which were surface mount with
side terminals. I've looked high and low for some of these, but haven't
had any luck. They'd be ideal for breadboard tube projects.

cheers

--
regards from ::
John Bartley
43 Norway Spruce Street
Stittsville, Ontario
Canada, K2S1P5
( If you slow down it takes longer - does that apply to life also?)



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John Bartley ) writes:
I'm not sure how to do the tubes in a DB format, but everything else
should be straightforward.

I'm not sure it completely translates to tubes, since "dead bug" seems
to suggest everything mounted on one side of the circuit board.

But people did take advantage of copper circuit board in tube circuits.
Invert the chassis, and use it merely to protect the circuitry.

Sometimes the tubes were mounted with a bracket (made of more circuit board,
and even soldered to the main board) on the copper side of the
board, the most obvious times were when the tubes were Nuvistors, but the
scheme was used sometimes when compact construction was desired. But usually,
the tube sockets were mounted in holes in the circuit board, and if aluminum
is easier than steel to work with, copper circuit board is even easier.

Once the tube sockets were in place, then everything would be wired up
as usual, with the difference being that it was really easy to drill a
hole for a coil, and every time a ground point was needed, it was a simple
matter of soldering the lead to the copper circuit board. No high wattage
iron or gun is needed, since the copper isn't really thick. If you need
to change things, it's relatively easy to disconnect that ground point,
and unlike with old methods, you don't have an extra hole if you do change
it. Leads could be short, because you could make ground connections where
they were needed rather than where there was a ground lug.

Because of the tube sockets, this tended to be a bit more formal than with
solid state devices, but it was still a neat way to build, and some of the
most busy builders used it because they were always trying to improve things.

Frank Jones did a lot of this sort of thing, at least after Nuvistors came
along. Even before that, many of his converter projects were built on an
inverted chassis, with a piece of aluminum for mounting the parts rather than
circuit board.

Bill Hoisington K1CLL wrote tons of articles in the sixties ane early
seventies, and pretty much everything was build on circuit board. He was
not concerned with looks, and the few times there were photographs, they
did look very "dead bug" like. He even built an amplifier with a 4CX250
or such on copper circuit board.

Michael VE2BVW

On Sun, 19 Oct 2003 11:59:57 -0400, John Bartley wrote:

David Forsyth wrote:
The "dead bug" way? I'm not sure what this means - please forgive me I'm
new to this :-)

Hehe, don't feel too bad. I have zero experience with solid state stuff,
so when I was told to build my trial projects in DBSF format, I was left
scratching my head. I laughed out loud when I was shown a "Dead Bug
Squashed Flat" project. This is your components laid out flat on a
perfboard and the wires run straight, point to point. It really does
look like a DBSF!!

I'm not sure how to do the tubes in a DB format, but everything else
should be straightforward.

"General Radio" used to sell tube sockets which were surface mount with
side terminals. I've looked high and low for some of these, but haven't
had any luck. They'd be ideal for breadboard tube projects.

cheers


Omron has surface mount sockets for thier line of relays, can't
remember if they're 8 or 11 pin though. Check it out, you might get
lucky .

John Bartley ) writes:
I'm not sure how to do the tubes in a DB format, but everything else
should be straightforward.

I'm not sure it completely translates to tubes, since "dead bug" seems
to suggest everything mounted on one side of the circuit board.

But people did take advantage of copper circuit board in tube circuits.
Invert the chassis, and use it merely to protect the circuitry.

Sometimes the tubes were mounted with a bracket (made of more circuit board,
and even soldered to the main board) on the copper side of the
board, the most obvious times were when the tubes were Nuvistors, but the
scheme was used sometimes when compact construction was desired. But usually,
the tube sockets were mounted in holes in the circuit board, and if aluminum
is easier than steel to work with, copper circuit board is even easier.

Once the tube sockets were in place, then everything would be wired up
as usual, with the difference being that it was really easy to drill a
hole for a coil, and every time a ground point was needed, it was a simple
matter of soldering the lead to the copper circuit board. No high wattage
iron or gun is needed, since the copper isn't really thick. If you need
to change things, it's relatively easy to disconnect that ground point,
and unlike with old methods, you don't have an extra hole if you do change
it. Leads could be short, because you could make ground connections where
they were needed rather than where there was a ground lug.

Because of the tube sockets, this tended to be a bit more formal than with
solid state devices, but it was still a neat way to build, and some of the
most busy builders used it because they were always trying to improve things.

Frank Jones did a lot of this sort of thing, at least after Nuvistors came
along. Even before that, many of his converter projects were built on an
inverted chassis, with a piece of aluminum for mounting the parts rather than
circuit board.

Bill Hoisington K1CLL wrote tons of articles in the sixties ane early
seventies, and pretty much everything was build on circuit board. He was
not concerned with looks, and the few times there were photographs, they
did look very "dead bug" like. He even built an amplifier with a 4CX250
or such on copper circuit board.

Michael VE2BVW