If your planning on running AM, there's a piece of test equipment made by B&K
that will help you tune an AM amp easy. The model B&K 1040 tester has a two
tone output into a small speaker which has a padded block of foam around it. It
is meant for the mic to be placed there and keyed. This will modulate the AM
carrier to tune your amp with. It has an adjustable output if I recall, plus
some other goodies like a watt meter and a swr meter. I'm not for sure what the
power rating is though on the watt meter or the internal dummy load. I'd
imagine it's not very much as it was designed to test CB's with, but it works
fine for any AM rig for this application. I built a small two tone outfit to
fit between the mic and the tranceiver. It has an adjustable level so you don't
over drive the rig and thus the amp. Those are very easy to make, and make
tuning a snap. Joe is right about AM, you tune for the PEP, not an unmodulated
carrier. Just make sure your PEP is not over 4X the carrier and your ok.
Best,
Will
*********** REPLY SEPARATOR ***********
On 4/14/06 at 7:48 AM Joe Isabella wrote:
>Yep -- my 950SDX is no different. If you just use the power adjusment,
>it actually lowers the entire power envelope and you gain nothing. The
>key is having the 100W (150W, in my case) PEP headroom while keeping the
>carrier reduced to a level that allows it to be fully modulated without
>exceeding final amp's headroom. Low-level AM is a whole different
>ani-mule than real plate modulation!! I've never messed with screen or
>series modulation, though.
>
> And then, driving an amp with AM is a whole 'nother can of worms, too.
>You MUST tune it with the highest PEP level you have from the rig. If you
>tune it just with your unmodulated AM carrier, it'll be mis-tuned and
>you'll splatter like crazy. Easiest way with a solid-state, low-level rig
>is to use fast CW pulses at max output (just like what you would do for
>SSB), then adjust the rig's AM carrier for the desired level (20-25W max
>for a 100W rig).
>
> Joe, N3JI
>
>
>Bill Turner <dezrat@copper.net> wrote:
> ORIGINAL MESSAGE:
>
>At 01:56 PM 4/13/2006, Joe Isabella wrote:
>
>> Tip 1: On the Kenwood, leave the power adjustment at max, and use
>> the carrier adjustment to lower it to <25W.
>
>*********** REPLY SEPARATOR ***********
>
>Joe's suggestion is correct. The Kenwood operator's manuals have the
>wrong instructions for AM. I've owned several Kenwood models and they
>are all wrong.
>
>73, Bill W6WRT
>
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