Re: [Amps] Current draw at 110 volts for SB-200 and SB-1000

[R.Measures <r@somis.org>]

On Dec 3, 2004, at 8:35 PM, Gary Smith wrote:

> Good friend of mine Marion, KJ6DB, has my old 811H, sez it works so 
> well he forgets about it.  Amp is three or so years old, I had it 
> wired on 220v, sent it to him he returned the jumpers on the xfrmr 
> input board to 117v, operates it on 10 mtrs sees about 600 watts or so 
> out, he drives it with an Icom 756, first model.
>
>  My .02 on this amp vs. say, the Heathkit: the SB-220 will operate 80 
> thru 10 (if it has the 10m mod kit in it) while the entire Ameritron 
> line will operate 160 thru 15, warc bands included, 12/10 mtrs, owner 
> modifiable.
>
> To answer this question before you ask it , operating the SB-220 on 
> 17/12 meters will strain the dickens out of the tank circuits with a 
> severe loss of power output. This is what I asked Jim Harbach the 
> heathkit mods guy, I am repeating what he told me.

Hello, Gary -- There is an approximate 10% increase in tank circulating 
current through the bandswitch by operating a SB-220, TL-922, L4, et 
cetera on 12m (using 10m position) or operating on 17m (using 15m 
position) -- but the strain is easily offset by decreasing the anode 
supply V -- i. e., using the CW tap on the HV to reduce the RF 
current..
-  note - due to skin effect, the additional heat is greater on 12m 
operation
> I know I maybe accused of beating the Ameritron drum too hard,  but 
> they are a fairly modern design assembled with modern (read easily 
> available) components for the bands we have available to us at what I 
> consider a more than fair price.

- Unless Ameritron amplifiers use more tank L for 12m than they use for 
10m, they have the same tradeoff on 12m as the SB-220, TL-922, et 
cetera.
- The Ameritron amplifiers that I have seen use no forced air cooling 
on the bandswitch or tank L, and they use tank L conductor sizes that 
do not adequately compensate for skin effect on 20m - 10m.


> 73 and so-forth,
> Gary, WA6FGI
>
> Oh how I wish for an new Alpha 99 and a Christmas tree full of neon 
> bulbs so I could light them up with no wires attached.

An 8171 does a better job -- and you can light up the neighbors'  
Christmas trees too.
> ...

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org

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