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Author Topic: Yaesu FC-800 Wire coupler  (Read 1507 times)
KK7KZ
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Posts: 464




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« on: November 18, 2005, 10:38:29 AM »

Anyone out there using an FC-800 with their FT-840? Talked to the folks at Vertex Std. and they say the tuner is limited to a 3:1 impedance matching ratio, i.e., 16.5 to 150 ohms. This seems wrong to me, I believe most wire tuners have very broad impedance matching ranges.
For those using the FC-800, how long are the interface cables (coax and control) and how long an end fed wire are you using?

Thanks!

Ron
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AA4PB
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Posts: 12893




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« Reply #1 on: November 18, 2005, 11:42:38 AM »

Something is wrong somewhere. Their specs do say 16.5 to 150 ohm range but another of their specs says covers 1.8-30 MHz with a 12M+ end fed wire. No way is an end fed wire going to stay between 16.5 and 150 ohms over that frequency range. It sounds like Yaesu has a marketing problem :-)

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WB6BYU
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Posts: 13335




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« Reply #2 on: November 18, 2005, 02:12:19 PM »

That is the problem with using SWR to specify a matching
range.

I suspect the problem is that the tuner won't match low
impedances on some bands - it might match 2000 ohms, but
not below 16 ohms (which limits its SWR at 3 : 1).  Actually,
even an impedance range such as 20 - 2000 ohms doesn't
tell you the whole story because there may be reactive
combinations it won't handle, or it may have a lot of
loss when matching impedances.

The ideal specification for tuner matching range would
be a Smith chart with loss contour curves on it, but
that is too hard for many people to interpret.  So we
get specs like, "matches up to 3 : 1 SWR" which leaves
a lot unsaid about the tuner capabilities.
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AA4PB
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Posts: 12893




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« Reply #3 on: November 18, 2005, 04:18:46 PM »

Actually the specs say up to 3:1 SWR *and* 16.5 to 150 ohms *and* it will load a 12M+ end fed wire on 1.8 to 30 Mhz. They must have some new type of wire if a 12M end fed length of it will present a load impedance between 16.5 and 150 ohms on all frequencies between 1.8 and 30 Mhz :-)
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KK7KZ
Member

Posts: 464




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« Reply #4 on: November 18, 2005, 04:26:09 PM »

AA4PB:
You are exactly where I am. It doesn't make a lot of sense and, WB6BYU, I am betting a lot of folks won't be pouring over a Smith chart to make a buy decision. According to AES, there isn't a product brochure on this product and the tech support guy at Vertex had to resort to an operations manual to scare up any info at all!

Funny that eham doesn't have an FC-800 in the Product Review section? Probably because they aren't widely used?

Oh well, I'll wait for someone who owns one to come forth and give us a report on how well they perform, if I'm lucky!
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KK7KZ
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Posts: 464




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« Reply #5 on: November 19, 2005, 09:03:46 AM »

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