Cecil Acuff wrote:
>>
>> Of course the pole pigs are big and heavy, but there's no rule the
transformer and PS has to be in the same cabinet.
## Put the HV supply on the floor, where it belongs, or the bottom
of a small 19" rack. If you do buy a new dahl/harbach xfmr, get LOTS
of taps. BTW, you can grab ANY 2 x sec taps. My dahl is tapped for
0-2300-3900-4800-5200 I was upset, cuz I forgot the 2900 tap.
Well 5200-2300= 2900 ! Knowing that info.. I would carefully spec taps
Also, having a 220/240 or 230/240 pri is a great asset. Then, between
pri and sec, you have literally loads of combo's. Buy one big xfmr, then you
can use it on ANY amp, with voltages from A-Z. A 46 lb hypersil runs $400.00
which is what`s used in the alpha 77dx/sx. Now $400-$600 may seem like
a lot of $$, but it's the most important part of the amp ! power starts with
the
xfmr. $400-$600 is cheap.. compared to the $8-9K alpha wants for the same
thing.
## you can always get all your money back on a dahl xfmr, and then some... or
just pass it on from father to son.
## I paid $75.00 for my 10 kva 4160/4800 hypersil pole pig, 120 lbs, just
under 1 cubic foot. You just can't blow it up.
## arnold howell, from howell tube sales has access to a LOT of pole pigs.
Smallest ones are 5 kva. He also has 2 x doz YC-156's [ youngstown ohio]
>
> -----------------
>> But lets say you have access to one of those ultra linear 3CX or
>> 3CPX5000 pulls with fantastic IM in the minus 50 db range, that can
>> comfortably run the legal limit using all of the drive from your 100
>> watt exciter.
## Roger. with 100 w of drive... you will send a YC-156 way over 1.5 kw
maybe 25-40w max.
> ----------------------------
>
> Can someone provide sourcing info on reliable, reasonably priced pulls
> for home builders to build with?
## www.ctrsurplus.com YC-156's $125.00 [419] 683-3535
if u dilly dawdle, you will lose out.. and probably have by now.
> Would love to buy a couple Triodes that don't require sockets. Would
> even consider tetrodes.
Another place
would be http://www.wa8wzg.net/forsale.htm which has been posted before.
## he's good too.
>
>> Winding the tank coils is easy, but may require sacrificing some copper
>> tubing while learning, or you can find some one who is good at winding
>> coils. Given the plate impedance, you should be able to find a design
>> to copy which makes placing the taps on the coils much easier. Also
>> good hefty toroids for the 160 and 75 meter bands is now the way to go.
## I'd dump any notion of using torroids on a HB amp. They run way too hot
and u have plenty of room. I have not wrecked a tubing coil..yet. Tubing
comes in
15-25-50' rolls. They are very easy to wind.. and silver plate with
cool-amp.
## Most of us use GM3SEK's PI spead sheet. Then u can design the entire
amp in abt 1/2 hr flat. I use a B+k 875-B [ mouser] to dial in the taps..
dead on the 1st time around. u want 2.6 uh.... well the meter reads down to
.1uh
Toss the GDO, it's useless for taps.
>
> > What about no band switch and no tapped tank....just a large edge
> wound roller inductor?
## I use a new RI-40 from SSON. $245.00 on my 3CX-3000A7
0-40 uh, tapered pitch at one end, and uses 3/8" edge wound silver
plated ribbon, .072" thick. 4 x gold plated contacts, [2 x per side]
pinch the ribbon. It's built like a tank, no torroids required.
Handles 5kw+. Just elevate it off the chassis by 2-4"
and at least one of them is
almost sure to hit one of the resonances for the plate choke.
## Use the rf parts/ameritron choke, or the alpha choke.
> bit more expensive but time and loss of materials to trial and error
> are expensive too.
##say what ?
When you take into account the cost of a custom band switch and the time
to get the taps correct
## It takes literally 5 mins to get all the taps correct.. and that's if ur
slow. The lcr meter makes short work of taps. It's ur #1 tool !!!!
You are dead with out it. The 875-B and other's will read down to
.1 pf.... and .1uh
>
> > I have been inspired by the posts of the last several weeks...
Now that I'm really glad to hear.
> to the point where I started looking for suitable cabinetry for
> building. Purchased two 19" rack mounted chassis that had contained
> 900Mhz radio transceiver systems from work. Should make excellent
> cabinets for home amp projects. All aluminum, probably 18" tall and
> 24" deep. Will require some work to add and remove some internal
> compartments but good starts for $25.00.
## Good. perfect size.
Remember too, that with an amp look carefully at how the commercial amps
are constructed. Most are of a modular construction with a single bottom
plate instead of building on the old 14" X 18" X 3" chassis like we used
to do.
## IMO, don't even try copying the no chassis route. I'll take a
hb 17" x 18" deep x 4-5" tall chassis any day. Input and
tuned input below chassis.. all output kw stuff above chassis.
Put the B+ supply in a separate box.. on casters... on the floor,
where it belongs. Or use a 4' tall rack.. with Rf deck at top,
HV supply at the bottom, use casters.
You might even want to build some metal working tools such as a metal
brake.
## I make all the chassis from flat panels.. all joined with 1" x 1"
angle AL. Any panel can be removed, or replaced,[ if u wreck one]
.... and put into the drill press, and drilled from either inside or outside
etc, then re-installed. You can even use an old chassis and put a
clean new AL plate on top,covering all the old holes.
I get all the al flat plates chopped to my specs.. at local sheet
metal shop. both the plates and the 1" x 1" are all 1/8" thick 6061-T6.
Easy to drill, cut, etc. Greenlee now makes combo drill+tap... super fast
to now tap a hole.. all in one motion. Use SS hardware.
## stick the $125.00 YC-156 in there.[ + mating pole pig]
... and a smile will come across your face when you realize you just
beat alpha, etc.. at their own game.
The YC-156 will make the $9K alpha look like a sick puppy. It will
make 4 of em look like sick puppies.
Jim VE7RF
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