[HBR] My Retro-Radio Project...

[hbr@mailman.qth.net]

Eddie said:

> These are borrowed from a fiend ...

Surely not the worst such, however ... a *first class* fiend would loan 
you a dull set that would raise nasty edges around the holes to 
bloody your hand when you install the sockets.   He'd throw away 
the anti-friction washers, too, and coat the screws with a good layer 
of rust.   The 5/8 punch would actually make a hole .666 of an inch in 
diameter.  The screws would be slightly bent so they tend to jam and 
the punch wobbles and 'walks' as you start to tighten it ...  And he'd 
loan you a worn out 6" Wal-Mart adjustable wrench to go with it.   
"These were my dad's things -- please take good care of them!"

Oh no -- I never make typos ... why do you ask?

> I actually "construct" the whole receiver on paper this way, drawing
> the resistors, capacitors, etc.---EVERYTHING. Then, as I actually do
> the soldering, I highlite each part on the paper as it is soldered
> into the actual circuit ... Does anyone else use this technique in
> building? 

No, and I admire your use of it -- this is clearly better than the way I 
do it.   

I spend hours playing chess with the large parts on top of the 
chassis to get the signal paths right, get the right stages next to the 
panel (for controls) and hopefully keep things that will interfere well 
separated.   I try to stretch the main signal path all across the 
chassis, wrapping it around uncritical stages, chiefly audio and  
power supply.   Things that make heat are separated from things that 
are heat sensitive -- tubes are away from VFO coils/capacitors and 
crystals; power resistors and output stages are kept away from filter 
caps.  If things start to seem 'tight,' that usually means a larger 
chassis is needed.   

What does the panel look like?   Is it reasonably balanced?   Can the 
controls be reached?   Will the panel controls interfere with the 
chassis?

There are the usual issues of capacitor gangs hitting stuff, meters 
poking through the panel into a tube, and so on.   Then I look at 
tubes that I know  will have more parts -- low level audio stages, plate 
detectors, and the like -- they need extra space.   Where will wires 
go through the chassis?   

Lots of space is needed near the plate transformer for terminal strips 
and filter caps.   Speakers should be given extra space because you 
rarely (these days) can find a duplicate if they have to be replaced.

Then I orient the tube sockets to place the grid and plate pins in line 
with the signal flow.   

Finally, I try to think of the things I *might* do, and leave extra space 
to make it possible.   For example the 1MHBR has ample space to 
add  a 1665 kcs IF stage and the added hole needed for the larger 
plate transformer that will be needed, is already drilled.   I didn't at 
first think I'd use a trimmer on the antenna circuit but I left space and 
later installed one.  I left a little extra space between the front end 
tubes and the tuning cap for a heat shield -- and the other day used it 
to install a substantial heat sink plate under the tubes.

There are always things I didn't think of.  I admire anyone who carries 
the process to actually sketching out the locations of the small 
parts.   

Walt
KJ4KV