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nuckolls.bob(at)aeroelect
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 Posted: Wed Jan 25, 2017 5:26 pm Post subject: iCom Antenna Switchbox effect on Com Radio |
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At 01:15 PM 1/25/2017, you wrote:
| Quote: | Bob,
I need an education. The SWR meter referenced here shows; Frequency Range: HF 1.6MHZ~60MHZ. How important are the range markings?
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Frequency range is important . . . and
there are several offerings that cover
other ranges of interest.
I tested the link I provided again and it
took me to . . .
"Digital VHF UHF Power & SWR Meter for Two Way Radio RED DOT 1051A 100~500mhz"
Bob . . .
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nuckolls.bob(at)aeroelect
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| Posted: Thu Jan 26, 2017 9:38 am Post subject: iCom Antenna Switchbox effect on Com Radio |
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At 06:56 AM 1/26/2017, you wrote:
| Quote: | Is there any significant benefit of a digital meter over an analogue one? Ive never trusted the fake precision of cheap digital meters.
|
Interesting perception. In actuality, achieving
digital precision has become jelly-bean technology.
There are 80-cent micro-controllers in my
drawers with 8-bit, a/d converters with
less than 1% error for all effects combined.
On the flip side, precision translation of feed
line characteristics from the realm of radio
frequencies to DC voltages proportional to
amplitude and phase has become the longest
pole in the tent.
Whether you display results digitally on
LCD/computer screen or analog on meters,
the dominant error sources are quality
of directional couplers (if used) and
linearity of detectors at the frequency
of interest.
Here are but two of many exemplar articles on
SWR measurement techniques.
http://tinyurl.com/jojys8k
I own one of the Red-Dot SWR meters.
The extra ordinary compactness of this
product speaks to a natural compression
of physical size as one climbs the spectrum
of radio frequencies.
It agrees most favorably with my BIRD 43
watt meter. At $50, it 'seems' cheep but
in this case, the thing performs well
and is a useful tool for resolving antenna/
feed line performance in the state frequency
range. I'm waiting for those guys to offer
another version on the transponder/TCAS range.
The short response is that analog to digital
conversion and display has become a rudimentary
process. I've had occasion to compare a number
of the least expensive Harbor Freight multimeters
against precision bench instruments. In every case
I've found the DC accuracy of these instruments
to be on the order of 1%.
Bob . . .
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alec(at)alecmyers.com
Guest
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| Posted: Thu Jan 26, 2017 10:03 am Post subject: iCom Antenna Switchbox effect on Com Radio |
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A transponder SWR meter would be great, but how are you going to get the output stage to transmit a carrier for long enough to measure anything with basic equipment?
On 26Jan2017, at 6:32 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com> wrote:
At 06:56 AM 1/26/2017, you wrote:
| Quote: | Is there any significant benefit of a digital meter over an analogue one? Ive never trusted the fake precision of cheap digital meters.
|
Interesting perception. In actuality, achieving
digital precision has become jelly-bean technology.
There are 80-cent micro-controllers in my
drawers with 8-bit, a/d converters with
less than 1% error for all effects combined.
On the flip side, precision translation of feed
line characteristics from the realm of radio
frequencies to DC voltages proportional to
amplitude and phase has become the longest
pole in the tent.
Whether you display results digitally on
LCD/computer screen or analog on meters,
the dominant error sources are quality
of directional couplers (if used) and
linearity of detectors at the frequency
of interest.
Here are but two of many exemplar articles on
SWR measurement techniques.
http://tinyurl.com/jojys8k
I own one of the Red-Dot SWR meters.
The extra ordinary compactness of this
product speaks to a natural compression
of physical size as one climbs the spectrum
of radio frequencies.
It agrees most favorably with my BIRD 43
watt meter. At $50, it 'seems' cheep but
in this case, the thing performs well
and is a useful tool for resolving antenna/
feed line performance in the state frequency
range. I'm waiting for those guys to offer
another version on the transponder/TCAS range.
The short response is that analog to digital
conversion and display has become a rudimentary
process. I've had occasion to compare a number
of the least expensive Harbor Freight multimeters
against precision bench instruments. In every case
I've found the DC accuracy of these instruments
to be on the order of 1%.
Bob . . .
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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