[RVRC] FW: Top secret???

Sat Apr 16 20:41:24 EDT 2011

RVRC Members,
There are several key issues that must be considered on an issue to raise 
transmitter power.
1.) the original repeater coordination that was based upon the transmitter 
output power and 'effective radiated power' at the time of coordination.
2.) any increase above the coordinated power requires an application to 
(currently) MetroCor and will certainly require a "NOPC" (Notice Of Proposed 
Coordination) which must be sent by MetroCor to our bordering coordination 
organizations for their approval or disapproval. This is a mandatory 
function and This could result in a nasty situation with respect to our 
bordering coordinating bodies.
3.) A substantial increase in transmitter power would affect the need for 
additional 'isolation' in the duplexer if the duplexer doesn't have enough 
protection for the current receiver at the higher transmitter power.
     (Raising transmitter power effectively reduces the 'isolation' of the 
transmitter to the receiver which consequently requires additional 
attenuation of the transmitter carrier at the receiver terminals. Increasing 
duplexer attenuation creates additional losses to the 
receiver........effectively reduces receiver sensitivity.)
4.) There would be no changes necessary if the amplifier was operated at the 
originally coordinated power level.

Fraternally,
Marv,  K2VHW
-------------------------------------------------------------

----- Original Message ----- 
From: "E Drew Moore" <drumor at optonline.net>
To: "RVRC" <rvrc at mailman.qth.net>
Sent: Saturday, April 16, 2011 5:14 PM
Subject: [RVRC] FW: Top secret???


> Bryan, thanks. Whenever we increase our power above 100 watts two things
> happen. 1.) We create intermod that effects the ETSNJ and the W2LI
> repeaters, and 2.) we impact repeaters outside of our coordinated area. 
> Both
> create undesirable consequences.
>
> -----Original Message-----
> From: rvrc-bounces at mailman.qth.net [mailto:rvrc-bounces at mailman.qth.net] 
> On
> Behalf Of Bryan D. Boyle
> Sent: Saturday, April 16, 2011 3:56 PM
> To: rvrc at mailman.qth.net
> Subject: Re: [RVRC] Top secret???
>
> On 4/16/2011 2:59 PM, njradioman at aol.com wrote:
>>
>> I don't feel we need an amp that puts out 250 watts.
>>
>> What do we want to do, start interfering with other repeaters, I don't
> think so.
>>
>> My vote is no .
>>
>> Let's stay with a 100 to 150 watt model.
>>
>> Marty
>
> This will run, as Scott said, at 100 to 150w comfortably.
>
> Advantages:
>
> 1. We can run it at less than its' full-bore rated power, it will
> operate cooler and shed less heat.  That it's capable of doing 250 does
> not mean that we necessarily SHOULD run it at 250.  The amp is capable
> of running at less than it's fully rated power by design without spurs,
> garbage, or harmonic and linear distortion of the signal. Henry tells
> you how, and rates the amp for running at less than full output.
>
> 2. Less thermal stress on the components.  250w is a lot.  So is 150.
> About a minimum of 40% less, though.
>
> 3. The amp is linear; less in (drop the exciter to 1w) and run at
> reduced power.
>
> 4. The difference between running 100w and 250w in geographic range at
> our HAAT is a lot less than the difference between 25 and 100.  The 625
> machine gets down here in PA fine (a little scratchy) at 25W.  That's 35
> air miles.  So, figure, @ 4x or more, the power increase will double
> that. (I'm as far from the site as midtown manhattan, fwiw.)
>
> 5. The cost to purchase an at-the-limit 100w amp somewhere down the road
> will be more than the cost to purchase this amp and have the factory
> (which has a good rep, I mean, who wouldn't want, even today, an Henry
> sitting on the floor in their shack...) recondition it.
>
> 6. The AC/DC power system was sized specifically to handle up to 40-45A
> load through the powergate into the battery backup, assuming up to 150W
> of transmitter/amp power.  The limiting factor will be how much power we
> would want the amp to generate which will determines the resultant load.
> The power supplies are capable of providing 60A of current at 13.8V.
> IF we are smart and not looking to throw blue flames and cook hot dogs
> close to Eric's tower, then keeping the total DC power draw (see above)
> under, let's say, 75% of the 45 amp capacity of the charge controllers
> will give us more than enough range.  IF we don't try and run at
> 250w..the system will handle it just fine.
>
> 7. Stated current draw at 250w is 45 amps.  Current draw at 150 would
> about 27 amps from my calculations, all things being equal.  The Icom,
> running at 25W input, is drawing a little over 8 amps.  Dropping the
> Icom down to 1W to tickle the amp to give us our desired output would
> draw a little over 3.5-4 amps (some of the power is used for other
> things besides transmit..have to drive the receiver and oscillator,
> etc..).  I show that as a total of 30.5-31 amps @ 13.8v to drive to 150w
> tpo into the duplexer.  Comfortably under the 75% of capacity of the
> charge controller.
>
> I don't see a downside to this.  Feel free to disagree, but this is my
> analysis and conclusion.
>
> 73 Bryan
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