Hi fellas
For 24 out of my 41 years as an Electrical/Instrument Engineer, I worked in Alumina Refineries. Both of the refineries I worked in were owned by US companies. The first - Worsley Alumina, owned by Reynolds Metals, the second (3 sites) by Alcoa.
Hence, both companies used Honeywell process control equipment. When I started at Worsley in 1989, I was trained in the intricacies of the equipment and one thing that stuck in my memory (being a radio ham) was their recommendation that ANY coax jumper cable had to be at least 10 feet long (even if the distance between connections may have only been 1 foot) as the cable needed time to establish it's inherent impedance. This sounded like voodoo to me, but your comment on the different swr seen with different length coax jumpers brought back the memory.
Any comments ?
Cheers,
John VK6JX
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-----Original Message-----
From:
[email protected] <
[email protected]> On Behalf Of Adrian Fewster
Sent: Sunday, October 29, 2023 3:24 PM
To:
[email protected]Subject: Re: [ham-amplifiers] Coax to connect between exciter and SB-200
I think the reason different lengths of coax effect measured swr is because its not a purely resistive load and is effected by reactance.
The type of swr measurement system would make a difference. Measured true power out compared to reflected would be better
with more expensive meters.
Some use an inline tuner to deliver dialled watts between amp and txcr.
If you replace the amp input with a purely resistive 50 ohm dummy load, do you see the same shift in measurement from 6" to 3 feet
coax patch length ?
73
vk4tux
On 29/10/23 16:43, Jim VE7RF wrote:
I still have not figured out why the interconnecting coax length
affects input swr.
Jim VE7RF
