[TenTec] OMNI VII vs. K3 ? Opinions invited.,

[Dr. Gerald N. Johnson]

No, a true wattmeter (Bruene design) takes the vector product of voltage 
AND current to produce DC proportional to power.

73, Jerry, K0CQ

On 4/25/2010 11:32 AM, N4PY2 wrote:
> In fact it is driviing the load with 36 watts in your example.
>
> When the wattmeter shows forward power of 100 watts and reflected power of
> 40 watts into a high swr, because the load is not 50 ohms, the wattmeter
> readings are false.  Traditional wattmeters are calibrated for 50 ohms.  The
> wattmeters really only measure voltage and assume the load is 50 ohms.  The
> 100 watt reading in this case for forward power is not correct because the
> load is not 50 ohms.  But it happens to work out that the true power is the
> forward power reading minus the reflected power reading.  All the true power
> is delivered to the load minus transmission line loss.  Transmission line
> loss goes up with SWR.
>
> Carl Moreschi N4PY
> 121 Little Bell Dr
> Hays, NC 28635
> www.n4py.com
>
>
> ----- Original Message -----
> From: "Rick - NJ0IP / DJ0IP"<Rick at DJ0IP.de>
> To: "'Discussion of Ten-Tec Equipment'"<tentec at contesting.com>
> Sent: Sunday, April 25, 2010 12:20 PM
> Subject: Re: [TenTec] OMNI VII vs. K3 ? Opinions invited.,
>
>
>> As always Sinisa, you are correct.
>> Nice to hear from you again!
>>
>> The one place I have seen a difference is when trying to tune a linear.
>> While varying the power on any Ten-Tec, and tuning the amp, it simply
>> varies
>> the output power of the amp.
>> I've had JA makes that seemed to jump around, like they would suddenly
>> reduce power.
>> Then I wasn't sure if the input power had dropped or if it was the
>> settings
>> of the amp causing the change.
>>
>> In any case I preferred the way the Ten-Tec tuned.
>>
>> Now something to think about.
>> If I run 100w on the Ten-Tec and 40 watts are reflected, then as you say,
>> the amp or antenna receive 60w.
>> If my non TT rig reduces the power to 60w, due to high SWR, it is putting
>> out 60W but it is only driving the load with about 40w.
>> Or is my thinking wrong?
>>
>> 73
>> Rick
>>
>> -----Original Message-----
>> From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
>> On Behalf Of shristov
>> Sent: Sunday, April 25, 2010 9:56 AM
>> To: Discussion of Ten-Tec Equipment
>> Subject: Re: [TenTec] OMNI VII vs. K3 ? Opinions invited.,
>>
>>
>> Rick - NJ0IP / DJ0IP<Rick at DJ0IP.de>  wrote:
>>
>>> ... this full power into 3:1 SWR
>>
>>
>> Hi Rick,
>>
>>
>> "full power into 3:1 SWR" is just a myth.
>> Did you ever read such a claim made by TenTec?
>>
>> There is nothing inside TenTec transceivers to make them to DELIVER full
>> power into a mismatched load.
>>
>> TenTec transceiver do not DELIVER full power into a mismatched load.
>> They just fail to reduce the drive with high SWR because they mis such a
>> circuitry.
>> Consequently, the FORWARD power stays the same, at 100 W.
>>
>> But we must remeber that:
>>
>>   DELIVERED power = FORWARD power - REFLECTED power.
>>
>> Power meters inside Orion, Omni VII, and virtually all the other rigs
>> display FORWARD, not DELIVERED power.
>>
>> With SWR = 3, we have:
>>   FORWARD power = 100 W
>>   REFLECTED power = 25 W
>>   DELIVERED power = 75 W
>>
>> Similarly, with SWR = 10, we would have:
>>   FORWARD power = 100 W
>>   REFLECTED power = 67 W
>>   DELIVERED power = 33 W
>>
>> The only thing that can make PA deliver full power into a mismatched load
>> is, of couse, a tuner.
>> TenTec transceivers are no exception.
>>
>>
>> 73,
>>
>> Sinisa  YT1NT, VE3EA
>>
>>
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