[NLRS] Hoffman boxes for transverters/PA's (Long, sorry!)

[John P. Toscano]

Trying to get back into building some of my own stuff (at least a little 
bit beyond "buy it, plug it in, turn it on", anyway).

I bought one of PyroJoseph's Toshiba 3456 50 watt PA's.  I need to put 
it into an enclosure with a nice big heat sink.  (It sucks 250 watts of 
supply power to make those 50 watts of RF, so the other 200 watts are 
excess heat!)

Before even starting on that project, I was seduced by his Spectrian 60 
watt PA for 2340 MHz.  This one needs an enclosure even more 
desperately, since it is just a bare circuit board.  (This one sucks 
over 400 watts of supply power to make the 60 watts of RF, so there's 
even more heat to dissipate!)

While I am enclosing and heat sinking these amps, I figured I'd prefer 
to do some of the complex interconnecting inside the enclosure, to 
minimize the connections and make it easier to move the systems from my 
fixed station to the rover and back.  I have SMA relays to do the T/R 
switching, and DEMI TRS boards to sequence the T/R relay, PA enable, 
Transverter PTT, and IF radio PTT (in that order on Tx, opposite order 
on release of Tx).

I was hoping to find a nice aluminum box to put these bits and pieces 
into, bolt a big aluminum heat sink to one side, and bring out the few 
external connections needed.  I figured an SMA connector for RF Tx (from 
transverter), another SMA conector for RF Rx (to transverter), an N 
Female connector to the antenna (common of the T/R switch inside the 
box), RCA phono jack for PTT Request, RCA phono jack for PTT Out to 
transverter, RCA phono jack for PTT back to the IF radio, +13.8 VDC @ 20 
amps for 3456 or +26 VDC @ 18 amps for 2304, and Ground.   Hmm, that's 
still a lot of wires to move around, plus the power, ground, and IF on 
the transverter!  And I haven't found aluminum boxes that seem to be the 
right size anyway.  So then I got the idea of using a bigger, 
weatherproof box, and putting the transverter inside with the PA and the 
rest.  Now, the external connections are IF, Antenna, Power, Ground, PTT 
in, PTT out.  Much simpler to move around between home and rover, and 
potentially ready for eventual tower mounting someday by being in a 
weatherproof enclosure.

So, finally, for the questions.

1) Does anyone have an inside track on getting Hoffman products at a 
discount?  They apparently make high quality boxes, but they are more 
expensive than the PA that would be going into it!  And they are 
apparently "local" (based in Anoka, MN).

2) I have been trolling eBay for deals on such enclosures.  To get the 
size I want, I can find steel boxes but not aluminum.  (Also fiberglass 
are available, but not an option for heat sinking purposes!)  Is the 
heat transfer from a PA bolted to one side of a steel box to a big 
aluminum finned heat sink on the other side of the 14 or 18 gauge panel 
going to be acceptable?  Of course, there's also one or two layers of 
paint there also, definitely on the outside and probably inside.

3) Assuming I don't travel through any hurricanes or tornadoes, is a 
NEMA 12 box rating good enough to put outside?  Or should I not even 
look at a box that isn't rated NEMA 4?  At this time, I imagine the 
boxes would spend most of their time well protected from weather by 
placement in either the attic of my garage (underneath the rooftop 
tower) or on a shelf in the back of my SUV when roving, but I want the 
options of possibly moving the boxes to the roof of the vehicle (shorter 
feedlines and less inside clutter), or possibly mounting the boxes on a 
tower if I ever get a "real" one.

Thanks in advance for any advice y'all can offer!

W0JT