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Author Topic: Hustler short HF mast  (Read 1909 times)
K9SA
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Posts: 6




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« on: October 05, 2001, 11:58:46 PM »

Anybody use the Hustler short (24") mast with the Hustler HF antennas?  I've got one and can't get a decent SWR on 20 meters.  My resonator is about 200 kHz wide on the long mast, but the lowest I can get on the short mast is 2:1.  Hustler says it should work.  I have 20' of RG8X in the line.  

Skip
K9SA
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WB2WIK
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Posts: 20666




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« Reply #1 on: October 08, 2001, 01:30:13 PM »

Yes, I've made the 2' mast work, but it's a challenge.  The whip atop the RM20/RM20S obviously needs to be adjusted, and it sounds like you've done that but still can't get the system to match.  Remember, the radiation resistance is even lower with the short mast and that places even _more_ importance on the excellence of your ground connection, at the base of the antenna.  If you think the ground requirements are severe with the full-sized mast: They're much more severe with the shorter mast, since the ground resistance is a larger proportion of the overall antenna radiation resistance.

I've had to scrape paint under the trunk lid and inside the trunk, and make multiple, very low-loss ground attachments for the whip base using the short mast.  If you continue improving your grounding, you'll find the whip does tune right down to a 1:1 dip in the 20m band, but you may not get quite the bandwidth you experienced with the longer mast.

73 de Steve WB2WIK/6
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K1TWH
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Posts: 104




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« Reply #2 on: October 15, 2001, 07:03:49 AM »

Skip,    the feedpoint resistance could be somewhat below 50 ohms.  Since you are measuring a 2:1 SWR this is likely.  Shortening the antenna system should do this to the feedpoint (or you have more loss in the loading coil then you'd want). You can place a shunt capacitor or inductor across the feedpoint to allow the 'extra' current to flow properly and bring the feed back to 50 ohms.  A good starting point would be about 200 pF from feed at the base of the short mast to the closest possible ground.
Tom Howey  WB1FPA
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N9RMR
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Posts: 1




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« Reply #3 on: October 20, 2001, 11:36:29 AM »

I have the long mast and I can't get better than 2:1 SWR on the 20M resonator.  The 75 and 10M resonators work well and tune much lower, but I can't seem to do any better on the 20M.  I make plenty of contacts on 20, so it works well even with the marginal SWR, but I'd like to get it lower.

-Bud
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N2HBX
Member

Posts: 162




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« Reply #4 on: October 20, 2001, 07:35:30 PM »

I have had rather good success with the short mast and 10, 20, and 75 Meter resonators on my work van (2000 Chevy Express).  I have it mounted behind the trim panel just above the taillight housing on the driver side.

One thing I found in my case was that I did NOT have to use the replacement rods packed with the short mast.  I used the stock rods that came with the resonators and obtained a good match.  So if you're trying to use the replacements, go back to the stock rods and see if it improves anything.

73, Larry, N2HBX
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KL7IPV
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Posts: 984




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« Reply #5 on: October 25, 2001, 10:40:57 PM »

I have used the short mast with my Dodge pickup and it tuned okay but not one to one. I did NOT use the longer antenna wire they supplied but retuned the one ones used with the longer mast. I also used a mobile MFJ tuner on all bands and it worked every time. You may have to use a tuner as well. It sure made it easier when I changed bands. Be sure to check each band and readjust all antennas after you tune one. The ones already tuned will change as you tune a new band. You have to play back and forth to get them all right. Good luck.
73
Frank
KL7IPV
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W2DI
Member

Posts: 136




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« Reply #6 on: October 27, 2001, 10:56:30 AM »

Skip;
I've used the short mast and feel it works very well on all hf bands - if you add shunt caps as Tom, WB1FPA suggests. You can get a near 1:1 match and respectible bandwidth.
An easy way to do this is to add a device like the MFJ mobile matcher near the antenna. It is simply a switch box with different value caps wired from feed line to ground. The one I used has 5 positions, 'A' being straight thru and 'E' being max capacitance - if I recall. I found position 'D' worked for 40 meters, 'C' for 20, 'B' for 17 & 15 and 'A' for 10 - but particular installations may vary.
These units really help and for $20 or so you can't go wrong. I had it in the trunk and ran a short feed line to the antenna (you must keep the length from the matcher to the antenna as short as possible).
Good luck. Hope this helps a little and 73 to all!!
Joe, W2DI
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