On 10/14/08 8:55 AM, "Jerry Flanders" <[EMAIL PROTECTED]> wrote:
> At 11:36 AM 10/14/2008, Lux, James P wrote:
>
>
>
>> On 10/14/08 8:06 AM, "Jerry Flanders" <[EMAIL PROTECTED]> wrote:
>>
>>> At 10:52 AM 10/14/2008, Lux, James P wrote:
>>>
>>>> <snip>
>>>> In days of yore with an
>>>> analog system, tight coupling between amp and exciter comes almost for
>>>> free.. You bring some convenient bias control input out of the exciter and
>>>> drive it with a "error" signal of some sort from the amp. (then,
>> you have to
>>>> deal with the whole negative vs positive ALC)...
>>>
>>> What is the "whole negative vs positive ALC" issue, James? I am not
>>> aware of any Amps that use a positive-going ALC voltage scheme, or
>>> any argument for its use. What amps use it?
>>>
>>
>> The SGC Power Cube uses positive going ALC
>
Of course, the SGC is so bullet proof that nobody hooks up the ALC anyway.
There are also a variety of lab type amplifiers (e.g. those from AR) that
have all manner of ALC inputs and outputs, but they're also usually
configurable or jumperable. (if you pay $50K for a 500W amplifier, you can
expect a fairly sophisticated interface)
My "take home summary" is that we shouldn't be expecting a PC based SDR to
do any of this (other than, perhaps, setting a maximum output level from the
exciter), and that the downstream stages (PAs) should protect themselves,
rather than trying to push functionality back into the SDR.
The one exception would be if you are building a highly specialized single
purpose system, where you are willing to tightly couple components for cost,
weight, or size savings.
Jim
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