Amplifier Opinion
 

Someone wrote "You don't need a linear unless you're on 80 meters - then
you really need a
biggie"


Agree and disagree

For example, let's start with a 100-Watt exciter then add an afterburner of
800 Watts. Doubling power is 3 dB and an S-unit is 6dB. So from 100W to 200W
is 3dB, 200W to 400W is 3 more dB, and 400W to 800W is 3 more dB for a total
of 9 dB or only 1-1/2 S-Units possible increase on the receiving end. One
can achieve almost the same result with a 3-element beam.

BUT Although one and a half S-Units does give a little more oomph while
working a pileup, it really comes into play for weak signal work where if it
gets you just up out of the noise on the receiving end, two way QSO's may be
possible where without the linear, the DX just can't copy. I can attest to
this many times on any band.



On the other hand I have worked DXCC - QRP - 5 Watts



A lot depends on propagation (of course)

--
CL -- I doubt, therefore I might be !

"Caveat Lector" wrote in message
news:sKpRe.1982$mH.1643@fed1read07...
Someone wrote "You don't need a linear unless you're on 80 meters - then
you really need a
biggie"


Agree and disagree

For example, let's start with a 100-Watt exciter then add an afterburner
of
800 Watts. Doubling power is 3 dB and an S-unit is 6dB. So from 100W to
200W
is 3dB, 200W to 400W is 3 more dB, and 400W to 800W is 3 more dB for a
total
of 9 dB or only 1-1/2 S-Units possible increase on the receiving end. One
can achieve almost the same result with a 3-element beam.


Not many can put up a 3 element beam for 80 meters, 40 meters either. Even
a rotatable dipole is not an option for most on 80. The amplifier will sit
on the same desk as the rig in most cases.
Granted it will not do anything for my receive.

I don't use my amp very much. It did come in handy as I was talking to a
portable station last Sunday morning on 80 meters. He had a bunch of static
and qrm (Shelby hamfest was where he was at) and by me running an amp I
could get over the local noise he had.

Just don't make the common mistake of thinking that the units on your
receiver's S meter are 6 dB. That can lead to some extremely mistaken
conclusions.

Hams keep insisting that an "S-unit" is 6 dB, while the marks on typical
S-meters almost never are, and sometimes are much different ( 2 dB for
example).

Roy Lewallen, W7EL

Caveat Lector wrote:

Agree and disagree

For example, let's start with a 100-Watt exciter then add an afterburner of
800 Watts. Doubling power is 3 dB and an S-unit is 6dB. So from 100W to 200W
is 3dB, 200W to 400W is 3 more dB, and 400W to 800W is 3 more dB for a total
of 9 dB or only 1-1/2 S-Units possible increase on the receiving end. One
can achieve almost the same result with a 3-element beam.

BUT Although one and a half S-Units does give a little more oomph while
working a pileup, it really comes into play for weak signal work where if it
gets you just up out of the noise on the receiving end, two way QSO's may be
possible where without the linear, the DX just can't copy. I can attest to
this many times on any band.



On the other hand I have worked DXCC - QRP - 5 Watts



A lot depends on propagation (of course)

"Roy Lewallen" wrote in message
...
Just don't make the common mistake of thinking that the units on your
receiver's S meter are 6 dB. That can lead to some extremely mistaken
conclusions.

Hams keep insisting that an "S-unit" is 6 dB, while the marks on typical
S-meters almost never are, and sometimes are much different ( 2 dB for
example).

Roy Lewallen, W7EL

The following are my findings on an IC751, which I had previously posted on
another NG:
"As an example; the Icom IC-751 S meter calibration procedure requires that
the S meter adjustment pot be set to S9 +40dB, with 5 mV at the antenna
input. The S meter should then be verified to show: S8 - S9 with 50 uV
input, and S2 - S3 with 5 uV input. Note that this approximates to 3.33dB
per S unit. The amateur standard has traditionally been 6 dB per S unit.

I have calibrated my IC-751 as per the manual instructions. 50 uV reads S9
+ 15 dB, and 5uV reads S5. Increasing the generator above 5uV requires 11
dB to reach S9, or 2.75 dB per S unit."

I have seen it claimed that linear amplifiers often provide more than the
theoretical gain, and that the cause is some indefinable ionospheric
nonlinearity rather than meaningless S meters!

Regards,

Frank

"Frank" wrote in message
news:wdCRe.226160$tt5.43044@edtnps90...

I have seen it claimed that linear amplifiers often provide more than the
theoretical gain, and that the cause is some indefinable ionospheric
nonlinearity rather than meaningless S meters!

Regards,

Frank

We should not confuse more than advertized gain with more than advertized
output, though. A 1KW amplifier could quite likely have 1KW output with 70W
in. That does not mean 1.2KW linear output with 120W in. Still, the extra
gain is useful; some claimed 100W radios will not put out 100W on all bands.

Tam/WB2TT