One would assume that he made his with a BNC connector according to his
own personal preferences and needs; while the instructions call for a SO-239
due to that particular connector being most fitting for the vast majority of
ham shacks out there. I think the lesson here is that you can use the
connector that best suits your use.
73,
Jeramy W5XTL
On Sun, Apr 3, 2011 at 3:42 PM, Franklin Tucker <frantuck@nac.net> wrote:
> The instructions call for SO-239 but the connector in the pictures show a
> BNC. Huh?
>
>
>
> From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
> On Behalf Of Jeramy Ross
> Sent: Saturday, April 02, 2011 1:25 PM
> To: geraldj@weather.net; Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Eagle -- power measurement
>
>
>
> Here's a simple and cheape solution that is easily homebrewed:
>
> http://k4eaa.com/dummy.html
>
> 73,
> Jeramy W5XTL
>
> On Sat, Apr 2, 2011 at 11:54 AM, Dr. Gerald N. Johnson
> <geraldj@weather.net> wrote:
>> While a 6AL5 and transformer could be cheap, the venerable HP 410B and
>> 410C used a smaller diode in the AC probe and they also made a 10:1
>> voltage divider and a coax tap adapter for this very purpose. So it can
>> be had ready made.
>>
>> One other technique is to use a water proof dummy load submerged in an
>> insulate water bath. Then monitor the temperature rise of the water. Its
>> best if the water is circulated and you know the amount of water and the
>> thermal mass of the dummy load. It can be calibrated by heating the
>> dummy load with AC or DC that's more easily measured than RF power and
>> setting the applied AC or DC power to achieve the same rate of
>> temperature rise of the water. Then there's no math, the test power
>> equals the applied Rf power. Called calorimetry and there are commercial
>> products for that too though probably neither readily available or
>> suited for 100 watts.
>>
>> Then there directional couplers with RF out that can go to an RF power
>> meter and head like the HP 432 and 436 families. Where the head can only
>> stand 10 milliwatts. And they can be used with a power attenuator. The
>> 432 and previous work with thermistors biased to get their resistance to
>> 50 ohms and the meter works by showing the reduced bias power required
>> to keep the thermistor resistance to 50 ohms. The later 436 family uses
>> thermocouples and load resistors sensing the temperature rise of the
>> load resistors and are much revered in the microwave industry, but a new
>> one with power head can cost the price an Eagle.
>>
>> 73, Jerry, K0CQ
>>
>> On 4/2/2011 9:46 AM, Roy wrote:
>>> Don't dismay...there's a way.
>>>
>>> A 52-ohm dummy load with a rectifier and filter cap yields an accurate dc
>>> voltage in proportion to the power being dissipated. Today's vom's and
> dvm's
>>> are pretty accurate (average the readings of all your meters). The
> rectifier
>>> can be a 6AL5 with its plates connected in parallel, and its heater
>>> connected to its cathode, so the output voltage rating is high enough for
> a
>>> kw. The plates are connected to the hot side of the dummy, and a 0.01
> disc
>>> in parallel with say a 1-uF connect to the cathode for a positive dc
> voltage
>>> out with a hold time for peak readings. It's inherently self accurate and
>>> requires no calibration.
>>>
>>> 73, Roy K6XK
>>>
>>>
>> _______________________________________________
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>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
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