[AMPS] 87a/89 v. 2500e

[km1h@juno.com]

On Mon, 07 Dec 1998 17:03:29 -0500 "Mark Levine, D.C."
<mlevine@compsol.net> writes:
>Hello all. I am contemplating the purchase of a new amp and am in the
>process
>of comparing features. I am not currently involved in any contesting, 
>so
>
>rapid band switching and tuning are not the priority, though output
>power is.  I have looked at the Henry 8K, but I do not want to keep 
>my
>SB 221 to drive it. Command claims full output with 80 to 90 watts
>drive. Is it reasonable to assume 3 3cx800 's in the 2500e will out
>perform the 87a/89 with the same input power ?  I would appreciate 
>any
>input. My sincere thanks to all who respond and Happy Holidays to 
>all.
>
The output power of a LK-800A ( three 3CX800's)  and the LK780 ( two
tubes) with 70-80W of drive varied only a few hundred watts. Outputs on
20M 2300W and 2100W respectively.
The tube is rated by Eimac at 23W drive which is an approximation;
pratical circuits indicate 40W as about the ideal.
When the drive was increased to 100-120W the LK800A linearly went up to
3KW but the LK-780 was into compression and at no point exceeded 2400W.

The LK800-TNY , or a modified standard unit with a 3000V Ep,  will output
a full 5KW PEP SSB with 130-140W of drive. Not recommended for CW service
which is why the TNY power xfmr had a vacuum relay selected HV tap. I
have no idea of the effect on tube life at those levels.

One conversion that I have not seen mentioned much is the Drake L-4B with
a pair of 8877's and a new PS. Granted, no 160M, but a great RF deck.

73  Carl  KM1H




>
>
>  Dr. Mark Levine WB2EQE
>    <mlevine@compsol.net>
>
>

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