On 30/06/2011 23:15, Denny Esterline wrote:
> With those types of numbers, I wouldn't be looking at individual cells.
> Wiring them all together is a real PITA.
> Consider the packs made for RC cars. The typical 9.6V pack (8xAA) can oft=
en
> be found for less than $10, and the 7.2V pack (6x sub C) for about $15.
Price is sensitive. I've usually seen the R/C packs cost more than=20
individual cells.
There are 3 identical 36 cell packs. The cells, fuse and connector are=20
fitted into a replica B104 box.
It won't take that long to assemble.

I have considered inverters and C cells.
* 6 or 12 C cells
* 1 Boost inverter to +45
* 1 Boost inverter to +120V or +150V
* 1 Buck inverter to +1.1V
* 1 inverting converter to -8V or -15V (Otherwise the RF/AF PA needs=20
grid bias battery, though it's not rechargeable. Current about 4uA worst=20
case. All the other valves will run at 0V to +1V grid as the g1 current=20
is still under 1uA with grid +0.5 above filament+ at low HT on these=20
unusual Russian valves)

But you need a lot of filtering in a Radio, also I kind of liked the=20
challenge of making dual conversion Superhet AM/FM/SSB=20
Receiver/Transmitter (20kHz to 130MHz receive, 1.8MHz to 70MHz Transmit=20
with no transistors or ICs. One "cheat" is to use a 6MHz and 150KHz wide=20
39MHZ SAW filters and a pair of 455KHz Ceramic filters (one 10KHz, one=20
3kHz approx).

The valves in the 455kHz 2nd IF become part of 1st IF (39MHz) in FM=20
reception mode to convert 1st IF Amp to limiter for FM

The VFO is likely free running and same on all bands with crystal=20
osc/Mixer with switched crystals to select band. (Collins Radio type=20
architecture)



I will recheck dimensions and prices to see if any R/C packs are=20
suitable. To fit cells in width, the cells are packed staggered, so the=20
shrinked on cover on most R/C packs is a problem.

Note that US sources are nearly useless for Ireland (there have been=20
good exceptions):
* High shipping costs
* Often very slow shipping
* Often won't take non-US visa
* Often won't ship outside US
* Customs always look for Invoice and charge VAT (21%) and duty.
* Minimum =806 Customs / An Post charge also
(Canada is worse though for postal/shipping)

EU (and some "partner" states):
* VAT charged already, no extra customs interference
* Moderate shipping costs & Time
* French postage expensive.
* UK (next door) can be more expensive and slower shipping than rest of=20
EU. Also Stg instead of Euro

Asia:
* Shipping often lower cost than EU neighbours
* If the price is less than =8020 and the customs label believed, then it=20
not stopped by Customs
* If price over =8020 it might be stopped (not always) and Invoice=20
required, =806 + 21% VAT added
* 2 to 5 days longer than EU unless customs stops it (adds 4 to 5 days).=20
Some Hong Kong as fast as UK!

Australia:
* Oddly about the same as Asia, Slightly slower and more expensive=20
shipping, Faster and cheaper than US. Some "alleged" Australia sellers=20
turn out to be Hong Kong.
--=20
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