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Author Topic: Is MFJ-1982LP End-Fed Horizontal Wire antennas good choice for SOTA FT8?  (Read 916 times)

Posts: 136

« on: January 06, 2019, 06:05:32 PM »

1. Is the below four End-Fed Horizontal Wire antennas (or EFHWs) a good choice for SOTA? It says NO tuner needed.

It is 132 feet antenna wire for  80 meters model, 66 feet for 40 meters model

Is is ok that I buy the 132 feet model, cut it half at 66 foot, install a small connector that will not 'distribute" RF much. I aim to reduce SOTA weight when I do plan to use 80 meters on a particular outing.

2. How much 'ball park figure' power derating for use in an experimental work, 100 percent full power, continuously? How much is 25 watts continuous power, equivalent to SSB PEP antenna rating?
3. Is it 'ball park correct' to use 20 meters coax, so that antenna is far away from PC RF noise, for FT8 SOTA, at LOW man-made NOISE hill top.

WHY the manual says, "As a rule, it's best to keep the feed line as short as possible".  Is that a specific characteristics for the type of antenna? May be it has SWR a bit higher than dipole?

Inside is 1:7 auto transformer and one capacitor. Transforming 50 ohm to 2500 ohm

Explained at 4 to 6 minutes of David Casler review

4. Grounding at match box

The manual says, "make a counterpoise with using 15 or 20 feet of wire and spread it out beneath the feed point. The driving resistance at the antenna's feed point is very high, so your ground need not be perfect in order to reference the cold end of the matching transformer to earth. "

"If you use a longer feed line (more than 10 or 15 feet), ground the matching network and your station equipment separately."

5. What is "RF in the Shack" as stated in manual? Is same as match box, counterpoise 15 or 20 feet at TRANSCEIVER, ok?

"If you use a longer feed line (more than 10 or 15 feet), ground the matching network and your station equipment separately."

MFJ-1982LP, $49.95. 30 Watts QRP, 80-10 Meters, 132 feet.
MFJ-1984LP, $39.95. 30 Watts QRP, 40-10 Meters, 66 feet.
MFJ-1982MP, $69.95. 300 Watts Restricted space, 80-10 Meters, 132 ft.
MFJ-1984MP, $59.95. 300 Watts Restricted space, 40-10 Meters, 66 feet.

Manual say, "All ratings are in Watts-PEP using the SSB or CW mode and transmitting 50% of the time or less per the ICAS (Intermittent Commercial and Amateur Standard). These ratings do not apply to long key-down power applications where the matching network could overheat. De-rate accordingly for these modes."

73 Simon

Posts: 234

« Reply #1 on: January 07, 2019, 07:25:48 AM »

You might want to re-post this in another forum. This one deals with antenna restrictions based on things like homeowner associations (HOA) and local laws.

SOTA is mostly "restricted" based more on stuff like size and weight (if you are backpacking, for example) rather than regulations.

73 de Steve KE4OH
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