[TenTec] ten tecs have 100 watts out on carrier??

[Bob McGraw - K4TAX]

>From a person that runs AM, a carrier is a carrier.  AM is the modulation 
mode.  CW is the modulation mode.  Hence the FCC emission definition of A-3 
for AM and A-1 for CW.

A radio rated at 100 watts CW or 100 watts SSB PEP both are the same power. 
A 100% modulated carrier, hence AM, has sideband power that is equal to 4 
times the carrier power.  Thus for a 100 watt PEP rated radio to correctly 
run AM the carrier must be reduced to 25 watts.  Then the PEP value is 100 
watts.

As to the fold back issue, the Japanese radios typically use the SWR 
monitoring circuit to adjust the drive to the PA.  Thus as SWR increases the 
drive decreases and output power goes down.  Now with Tentec radios since 
the Paragon and Omni series, they monitor PA current.  As PA current 
increased above a pre determined value the drive to the PA decreases.  This 
is specifically effective when load Z is below the design value of 50 ohms. 
The smart part of this design is the fact the with supply voltage constant 
at 13.8 volts as load Z decreases, drive decreases but only where PA current 
exceeds a certain value.  Therefore the input power, volts x amps, is a 
given and the output power remains almost constant regardless of load.

Now what must be realized is the fact the SWR is not a simple indicator of 
load.  If the load is 50 ohms the SWR is typically 1:1.  If the load is 150 
ohms the SWR is typically 3:1.  Now here's the kicker, if the load is 16.6 
ohms the SWR is also 3:1.  By monitoring PA current the DC power into the PA 
is controlled and maintained a safe value, specially with low impedance 
loads.  The system can still deliver rated power into SWR values of loads 
both higher than 50 ohms and lower than 50 ohms.  Simply monitoring SWR 
won't allow this to happen thus the reason the Japanese radios fold back 
power with SWR values above a specified amount.  Each radio company 
determines where the foldback point begins.  Some choose 1.5:1 while others 
choose values like 3:1.

73
Bob, K4TAX


----- Original Message ----- 
From: "john ferro" <foxbat426 at hotmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Sunday, September 30, 2007 3:59 PM
Subject: Re: [TenTec] ten tecs have 100 watts out on carrier??


>
> actually you have not helped me out - you still have not answered the 
> question - whats the difference between an am carrier and cw carrier? if 
> it's the same as some people say why on a japanese radio the am carrier is 
> only 25 to 50 watts (depending on the radio) when the mic is keyed vs. 100 
> watts on the same jap radio cw mode keyed down - all assuming swr is 1? i 
> understand the swr fold back issue.> From: OTAKEBI at aol.com> Date: Sun, 30 
> Sep 2007 16:39:52 -0400> To: tentec at contesting.com> Subject: Re: [TenTec] 
> ten tecs have 100 watts out on carrier??> > Yes, Mike.> Now we know what 
> was going on once he explained it a little better.> I had a TS 180s that 
> at had to see a perfect, flat, SWR to put out full > output.> Like Ten 
> Tecs better.> Glad we were able to help him.> Dan/N4VET> > > > 
> ************************************** See what's new at 
> http://www.aol.com> _______________________________________________> 
> TenTec mailing list> TenTec at contesting.com> http://lists.contesting.c
> om/mailman/listinfo/tentec
> _________________________________________________________________
> News, entertainment and everything you care about at Live.com. Get it now!
> http://www.live.com/getstarted.aspx
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>