Date: Thu, 25 Mar 2010 07:30:45 -0700
From: James Colville <jimw7ry@gmail.com>
Subject: Re: [Amps] 'Good engineering'
I'm sure glad I have a delete key. And a spam box.
Oh... And by the way Jim (VE7RF).... The legal, moral, fair, and gentlemanly
allowable power output here in the US is 1500 watts.
73
Jim W7RY
## That's funny. The fellow at AES tells me the big slugs
for the BIRD/CD line sections were literally flying off the
shelves that week I ordered 5 x of em. [ mine were small to big]
There was a big contest coming up apparently.
## legal limit here is 2250 w pep on ssb.... measured across a Z
matched load. The load is the ANT. Allow for just .5db line loss
[11%].. and now I gotta generate 2.5 kw... just to get 2250 w
at the top of the tower ! Now if feedline loss is 1 db [21%],
now I have to generate 2848 w pep... to get 2250 w pep to top
of tower.
## Kinda tough for me to generate 2.5 kw.. much less 2848w
from a 8877, without putting the IMD into garbage land.
2 x 8877's is just not cost effective..even Chinese 8877's.
## legal limit on AM is 800 W cxr. That's 3.2 kw pep.. with 100%
pos modulation.. and 4 kw pep.. with 125% pos modulation....
and 4.8 kw pep.. with 150% modulation.
## To get 4.8 kw pep to the top of the tower with just 1 db of
feedline loss [21%] requires the amp to put out 4800/.79=6075 w pep.
## typ tank eff on the high bands is 50-60%, on a linear amp. That
requires a lot of anode diss. Now if you want to dabble with quasi
class A modes.. and superb imd... u need even more anode diss.
## What tube do you suggest I use ?? BTW... CTR surplus is selling
YC-156's for $125.00 .. but you better hurry, he doesn't have many left.
www.ctrsurplus.com [419] 683-3535. Arnold Howell, of Howell tube sales,
has abt 26 x YC-156's left. [ youngstown, ohio] CTR is also in Ohio.
## what's moral, ethical, or gentlemanly to run 1.5 kw into 6 x yagi's on
a big tower.. with an ERP of 8-15 kw ??? And then scream into the mic
for 48 hrs straight, making thousands of useless qso's ??
## meanwhile, 2 kw into an inverted vee on a noisy 160/75m band,
during summer months... is a... 'no-no' !
Jim VE7RF
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