[Amps] Why people don't build amps.

Thu Mar 25 16:10:33 PDT 2010

An interesting thread this one...

Here's my penny...

Having spent considerable time trying to get a commercial 50mhz amplifier to work as advertised, and learning from the experience, I decided I'd like to built my 
own amp.

Starting small, a single band, GI7b from scratch has taught me quite a lot so far and I'm not finished yet.... i've been following the YU1AW design tagged as 'lazy 
build' for 50mhz.

I'll agree that it would have been cheaper to buy an amp, but I'm having more fun building, plus I'm learning a lot more from the experience to boot!

I'll be posting some info on my website when complete. 

73,
Andy
http://gd0tep.com

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On Behalf Of Shon Edwards
Sent: 25 March 2010 21:29
To: amps at contesting.com
Subject: Re: [Amps] Why people don't build amps.

I love this posting.  So true. I fall into the category of "technical, but not an engineer".  It is true that many of the up and coming ham generation is not very 
technical.  I have three sons, aged 9, 9, and 11 (two technicians and a general) who are new hams this year, and I'm just glad to get them passing their exams and 
operating on our equipment in a proper way.  All we can do is help them to learn if they want to go that way.
Otherwise, I have no solution.

As for me, even though I could build much of what I use, I'd rather buy it (as the initial poster says, it's often just as cheap to buy the equipment, especially 
used) than build it, because with such complex equipment, I'm not sure I trust myself with hundreds of components.  This is especially true of, for example, the 
Elecraft radio kits.  I'd love to own one; I've heard nothing but good about them.  But what if I botched it somewhere?  And with components as expensive as amp 
components, I am definitely worried about this.  I'd rather buy one new or even used (I found one used (10 hrs. only), an Ameritron AL-1500 for only $1900 -- truly 
a bargain) if it looks like it's in good condition.

73 de Shon KO3U

On Thu, Mar 25, 2010 at 2:56 PM, Cecil Acuff <chacuff at cableone.net> wrote:

>
> ----- Original Message -----
> From: "Roger" <sub1 at rogerhalstead.com>
> Cc: <amps at 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
>
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>

--
Shon R. Edwards,
BA (German/French/Computational Linguistics), MA (Computational Linguistics), AG (Czech Republic)

Radio:
Amateur Call:  KO3U
Commercial radio licenses:
GROL:  PG00016801
GMDSS/O/M:  DB00000391
GMRS:  WQKW341
2nd class radiotelephone:  T2GB064388
Accredited VE:  W5YI, ARRL
ARRL Instructor

1039 N 2575 W
Layton, UT, 84041-7709
USA
e-mail:  sre.1966 at gmail.com
phone:  (801) 444-3445
cell:  (801) 336-7635
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