Gangue,
I just checked my
mailing software and see that most everybody has their AT2
Buildathon kit. Of course, DX builders won't have them for at
least another week. Canadian kits went to a friend, Erci
Gunter, who gave me an American address. I sent the Canada
orders to him and he will forward them to the Canadian
builders. There are still undelivered kits to Canada from the
QSO Expo Buildathon in early March as Canada Postal Customs
apparently severely bogged down or on lockdown so Eric offered
to get Canadian kits through.
I've had many
questions from individuals about parts, pictures, docs, other
people building or finishing their kits etc. I just can't
respond individually to each query and do justice to the
group. Please sign up to my Groups.IO mail list and post
questions, suggestions, help etc to the list so we can all
benefit from the exchanges. Use the AT2 Buildathon: at the
beginning of the subject line so we can all filter them to an
email folder for easy collection.
I had lots of QRPme
orders backed up from when I was FULL TIME on the AT2 kits in
the kitting & shipping effort. I had to take care of that
business as best as possible before I could get back on this
project. I got my AT2 bench 1/2 cleared off and hope to finish
that chore later tonight. I will shoot another video or two
late tonight and tomorrow morning and post them ASAP. The 1st
one will be an overview of the AT2 project, what's what and
how to proceed. All of you have waited an extraordinarily long
time to get the kit so don't try to build it in one night.
Lets take it slow and sure so everybody is on the same page.
I'm not saying we all have to build it at the same time and
speed. I just want everyone understand the pertinent
information on the overall project before they jump into the
building process.
For instance Questions
fielded:
1: Two standoffs
instead of four on the Chinese HV brick on the power supply:
Yes, opposite corners of the board work just fine. It's not
going to go anywhere with two 6-32 bolts and nylon insert lock
nuts.
2: Miniature tube
socket but no tube: I always include extra FUN stuff with my
QRPme kits. With the discovery of the Chinese HV brick, the
high voltage power supply problem was solved. No back to back
'wall warts' were needed and no complicated and dangerous
linear power supplies had to be built......but there are
purists in every crowd. I spent a couple of months trying to
solve the 'double wall wart back-asswards' cheapo HV power
supply trick. Not only did I burn up several hundred dollars
worth of wall warts, I also went through about $200 in back to
back filament transformers too! I managed to get both
approaches to work but the costs were astronomical. I started
with engineering calculations and picked more QRP reasonable
parts that would appear to have the nads to do the job. They
all self destructed as I worked my up from QRP (budget)
friendly parts to more QRO models. Both approaches work ONLY
when you OVER spec'ed the parts by a ton. I ended up working
with the TOP END of the performance specs which resulted in
power supplies costing over $25 just in transformers. Back to
back filament transformers worked a little better but not
much. I ended up finding that Hammond Manufacturing still
makes plate/filament transformers for the guitar amp rebuild
market but they are in the $30+ price range. Hence the Chinese
HV brick. They are cheap...but noisy. You may have to use a
T/R switch to de-power the brick on receive depending upon
your situation. I did add a spot on the power supply where you
can hook up the output of a plate transformer and added the
parts to make a decent CLEAN high voltage power supply if you
want. The miniature socket if for and OA2 tube for voltage
regulation if you want to go that route, but you have to
supply the tube. You could also do a little rework on the pcb
and crank up the Chinese HV brick and then have an OA2 tube to
regulate it to 175 volts... BUT it is an AT2 (Acorn Tube 2)
kit and not an AT2+1 kit.
3: Yes, two mounting
holes for the crystal and the polyvaricon tuning capacitor.
Crystal socket uses #4 x1" steel bolts & 1/4" nylon
standoffs while the capacitor uses #4x1" black nylon bolts and
5/8" nylon standoffs.
4: The DB-15 connector
is to tear apart (very carefully) to get to the socket pins
that will be used to mount the acorn tubes to the circuit
board. I soldered (very very very carefully) my tube onto the
adapter boards but was advised by Colin, G3VTT, not to have
everybody do that. Too much soldering heat will ruin the
pin/glass seal on the acorn tubes. I discovered that DB
connector pins and socket dimensions were the exact same
dimensions of acron tube pins. AGAIN, QRP pricing problems
became an issue here. I had some NOS socket pin connectors in
my junque bins left over from projects in the early 70s. THOSE
socket pins are supper. Modern day DB connectors have modern
day manufacturing quirks associated with them. Most new
cheaper sockets have stamped pins. One can by machined pin
version DB connectors but only if they had recently won the
lottery and was still flush! So you very carefully take apart
the DB connectors, get the pins, re-bend them to fit the
socket/tube layout and secure tham to the tube pins with
shrink tubing. You can also search YOUR junque bins and
sources for OLD vintage DB cables with the quality machined
pin sockets and use those. Again, I couldn't afford to include
them in a QRP kit priced at $50.
OK, I'm going to close
this out for now and go work on the laser cutter. I have a
bunch of Lunatic AT2 enclosures I have to cut out. I hope to
get all those orders in the mail on Monday. I'll probably work
on AT2 videos and pictures early tomorrow morning and post
them after I clean them up.
Rex? W1REX
David Wilcox K8WPE
Bob Benedict, KD8CGH