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Re: [Amps] Rice Box Exciter to Collins 30S-1 & 30L-1

To: Joe Isabella <>
Subject: Re: [Amps] Rice Box Exciter to Collins 30S-1 & 30L-1
From: R.Measures <>
Date: Thu, 8 Jul 2004 03:08:56 -0700
List-post: <>

On Jul 7, 2004, at 6:50 AM, Joe Isabella wrote:

Hi Roger!!
I've been running "Rice Box" AM for some time now, and the trick is to keep the drive below the point that rig distorts. I know that all the manuals say "40W on AM", but I've found that power level includes more distortion than I like to see. If you keep it down below 25W you'll be in great shape. In fact, I've talked to a few guys running the 756 series into an amp and they sound pretty good!

 Indeed, Joe, when run properly (at a 4 to 1 ratio), low-level modulated, linear-amplified AM has way less audible distortion that traditional plate-modulated AM.

The only caveat to this is that the amp must also be kept below it's maximum PEP level, too. If you use the 30L-1, that's 1000W PEP or APPROXIMATELY 250W carrier on AM. You'd do well to reduce the 756's output to keep it down to around 200-225W or so. I used to drive a Kenwood TL-922 at about 250-300W carrier and it seemed quite happy at that level. I now have a Henry 3K-A, and it will easily go above the APPROXIMATE "legal limit" of 375W carrier on AM. I would bet your 30S-1 is similar in this regard.. I simply reduce the drive until I see around that level and all is well. In case you haven't caught on yet, the "rule of thumb" is power out in PEP is approximately equal to AM carrier x4. It totally depends on the audio (sideband) levels coming from the exciter. I hope I'm not insulting you with oversimplified statements!! Feel free to contact me off-line if you want to discuss this more. BTW, I now run a Ten-Tec Jupiter with my Henry for an all made in the USA shac
k. I
guess you could call it a "Wheat Box" instead (??). :-)

Also, I live a little north of you in the DFW area, so we could easily setup a sked if you like. I currently have my shack disassembled, but it will be back up by the weekend.

Best of luck and 73!!
Joe, N3JI
Lewisville, TX

Roger Agnew <> wrote:
I would like to get on an AM Net tomorrow with my Icom 756 Pro driving my Collins 30S-1 or 30L-1. Does anyone know or could guide me to a source of information to properly drive these amps with the Icom 756 Pro.

Roger Agnew K1KQ - Austin, TX 888-536-5500

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Richard L. Measures, AG6K, 805.386.3734.

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