Linear amplifier chain choices

[kennnick@gmail.com]

I'm doing my first SSB homebrew project and am learning a lot as I go.
It's for 60 meters.

I've done the speech amp, DBM, crystal filter, transmit mixer, and one
stage of post mixer amplification. This has taken me to about +6 dBm,
and I want to get to +30 dBm. (I've already built a 1 watt in / 10
watt out "final" amplifier.)

My question has mostly to do with the number of stages and operating
class. As I approach 1 watt, class A gets pretty impractical due to
device dissipation, or so it seems. But I want to carry waveform
faithfulness as far as possible. Is it accurate to say that if a class
that doesn't give full swing in both directions is used, a harmonic
filter should be used before the next stage? I'm trying to infer from
what I see in the literature. I'm generally seeing a single device
(not push pull) in AB (I think) just before the output filter, but not
often at the lower levels.

I guess a push-pull stage could be used to give waveform linearity to
get to the 1 watt level. I just don't know if that's needless
complexity(?)

The next decision is whether to go from +6 to +30 dBm in one stage or
not. I'm inclined to think 14 dB in one stage followed by 10 dB in the
next would be best. Any guidance?

73--Nick, WA5BDU

[eternalsquire@comcast.net]

Have you put up a page for the design?

The Eternal Squire

[Allodoxaphobia]

On 12 Dec 2005 17:51:48 -0800, wrote:
> Have you put up a page for the design?

Does *who* have *what* page up for *which* design.

SHEESH!!
These sloppy-assed Goggle followups will be the death of usenet.

http://oakroadsystems.com/genl/unice.htm#quote
http://groups.google.com/googlegroups/posting_style.html#summarize

[Michael A. Terrell]

Allodoxaphobia wrote:
>
> On 12 Dec 2005 17:51:48 -0800, wrote:
> > Have you put up a page for the design?
>
> Does *who* have *what* page up for *which* design.
>
> SHEESH!!
> These sloppy-assed Goggle followups will be the death of usenet.
>
> http://oakroadsystems.com/genl/unice.htm#quote
> http://groups.google.com/googlegroups/posting_style.html#summarize


You can always killfile everything from Google groups.

--
?

Michael A. Terrell
Central Florida

[Saandy , 4Z5KS]

.....so, first of all a class A amplifier would dissipate aproximately
1W which isn't so bad. any TO-5 transistor with a clip on heatsink will
take that. A 2N5109 would be ideal, being a quite rugged device. you
don't have to worry.
second, about 12-13 dB of gain in the HF range would be an approximate
maiximum for easy and comfortable construction. higher gains are
possible, but you start to endanger yourself with oscillations. better
a 2 stage amplifier, even though it sounds more expensive. it's only
one of a kind so cost shouldn't be a main concern.

[Allodoxaphobia]

On Tue, 13 Dec 2005 06:14:15 GMT, Michael A. Terrell wrote:
> Allodoxaphobia wrote:
>>
>> On 12 Dec 2005 17:51:48 -0800, wrote:
>> > Have you put up a page for the design?
>>
>> Does *who* have *what* page up for *which* design.
>>
>> SHEESH!!
>> These sloppy-assed Goggle followups will be the death of usenet.
>>
>> http://oakroadsystems.com/genl/unice.htm#quote
>> http://groups.google.com/googlegroups/posting_style.html#summarize
>
> You can always killfile everything from Google groups.

Iive started doing that -- on a ng-by-ng basis -- when it appears to Get
Out Of Control. Now it looks like I need to start killfiling the google
followups in the rec.radio.amateur.* collection.

It's so frustrating to follow some 'interesting' thread over a period of
days and be forced to stumble through a number of thoughtless,
disembodied followups.

sigh...

[Michael A. Terrell]

Allodoxaphobia wrote:
>
> I've started doing that -- on a ng-by-ng basis -- when it appears to Get
> Out Of Control. Now it looks like I need to start killfiling the google
> followups in the rec.radio.amateur.* collection.
>
> It's so frustrating to follow some 'interesting' thread over a period of
> days and be forced to stumble through a number of thoughtless,
> disembodied followups.
>
> sigh...


I know what you mean. Take a look at news:sci.electronics.design
sometime at all the off topic questions and flame wars.

--
?

Michael A. Terrell
Central Florida