Ebay but you have to check OFTEN and in multiple categories. Sometimes
they appear with "Buy-It-Now" options and can be had for a song. There
was a Dahl plate xmfr listed a few weeks ago that lasted about 3 hours.
It had a buy-it-now option and was snatched up right away. It was a
sweet xmfr, multiple taps on the pri and a hefty 3000vac 2 amp secondary
but it was heavy, around 66 pounds. Sounds good to me. It was also
listed in a somewhat non-related category, like "classic stereo
receivers" or something like that.
CraigsList is another option. When I search in the San Diego area it is
usually pretty slim to none. When I broaden the search to all of
California and/or look in Arizona (a 2 hr drive, very reasonable) a lot
more stuff opens up. Even if I do not have an immediate need sometimes I
will buy an item just to stockpile the junkbox.
Swap meets are sometimes a good option. I do not know if this is a
Southern California thing or not but every 70's era drive in movie
theatre now was swap meets on sat and sun.
Check qth.com and eham.net as well as qrz.com, check often. There is
stuff avl out there for very reasonable prices but it takes effort to
find them because guess what? Other hams and builders are looking too.
Murphy's Surplus is a good source. His web site is undated often so
represents a fairly accurate inventory. There used to be a nice outlet
by Los Angeles called "C & H Sales", they were all surplus like Murphy's
but had a slightly different inventory. They used to have GE 32uf 4500
volt oil filled caps for about $49.00. That was a long time ago, maybe
early 90's. I think they have since shut down.
I think Harbach has more or less taken over the Dahl designs. Kind of
pricey but certainly an option. Good luck in the search!
Lane
Ku7i
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
On Behalf Of Cecil Acuff
Sent: Thursday, March 25, 2010 12:57 PM
To: Roger
Cc: amps@contesting.com
Subject: Re: [Amps] Why people don't build amps.
----- Original Message -----
From: "Roger" <sub1@rogerhalstead.com>
Cc: <amps@contesting.com>
Sent: Thursday, March 25, 2010 2:56 PM
Subject: [Amps] Why people don't build amps.
> What are the sources for inexpensive transformers that will
> do the job? Not microwave ovens, those things get hot and are not
> designed for continuous operation. OTOH if one is willing to put up
with
> their short comings they can be paralleled to provide power for a
medium
> size amp.
----------------
Interesting post...I have some of the same questions. Options for
inexpensive, reasonably sized plate transformers?
-----------------
> 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.
----------------------------
Can someone provide sourcing info on reliable, reasonably priced pulls
for
home builders to build with?
Would love to buy a couple Triodes that don't require sockets. Would
even
consider tetrodes.
-----------------------------
> 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 would be more interested in learning how to properly wind, measure and
tap
using my GDO than shotgunning it. I have used the copy cat method and
it
works fairly well but I desire to understand.
Are there books that describe the process for those of us who are
technical
but not engineers?
What about no band switch and no tapped tank....just a large edge wound
roller inductor? Maybe a good bit more expensive but time and loss of
materials to trial and error are expensive too.
----------------------------
> Now lets go back to that legal limit issue. I'm not condoning illegal
> actions, but what is really more ethical, running a 2 or 3 KW amp with
a
> very clean signal,
----------------------------
I'd much prefer to build and operate an amp capable of 2500W ICS at the
legal limit and not worry about splatter and stressing expensive
components.
(or duty cycle)
Post raises several good questions for those of us that want to
homebuild
but seem to have more questions about doing it right than answers.
I have been inspired by the posts of the last several weeks...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.
Cecil
K5DL
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