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Author Topic: Tuning Hamsticks  (Read 2473 times)
KC2NYU
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« on: February 11, 2013, 12:31:04 PM »

Bought a rotatable dipole rig at Hamfest and it came with 2 Hamsticks or HF Power Rods as the package says- so guess they are from another mfg. I have never worked with Hamsticks before and have a few basic questions:

- Instructions that came with the sticks says cut off the bottom of the whip so it does not extend down into the coil. I see the part of the lower section of the stick where the coil is.
-- So does that mean right off the bat, cut the stinger so it never extends into the coil or should I try to tune them first??
- Gent I bought the rig  from gave me two sticks marked "for 20M" and said about 9 1/2 inches of whip should extend for 20 meters. I would like to have enough whip so I could tune up and down the band.
-- If you were to tune it from bottom to top of 20M band, how many inch range are we talking about , moving the stinger in and out?
-- Can anyone give me some hints on tuning these or a links to some Hamstick or rotatable dipole How To sites or references?

73 Paul kc2nyu

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K5LXP
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« Reply #1 on: February 11, 2013, 12:38:43 PM »

The difference between tuning from the middle of the CW portion to the middle of the SSB portion won't be very much, maybe a couple inches at most.

What I would do is substitute a piece of stiff wire and determine your length that way.  Once you've got a length that you can both adjust across the band and not have too much inside the coil, you can cut and then substitute your final stinger.

Do you have an analyzer?  If not you'll have to work iteratively across the band with a transceiver and an SWR meter.  The procedure to tune it is pretty much set both stingers to an equal length, find your minimum SWR point, then trim to get the minimum point(s) where you want them.  On my mobile setup I scored the adjustment points for CW and SSB onto the whip with a file.


Mark K5LXP
Albuquerque, NM


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W8JX
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« Reply #2 on: February 11, 2013, 12:55:04 PM »


- Instructions that came with the sticks says cut off the bottom of the whip so it does not extend down into the coil. I see the part of the lower section of the stick where the coil is.
-- So does that mean right off the bat, cut the stinger so it never extends into the coil or should I try to tune them first??


I have used Hamsticks for 20 years. When tuning them, as you shorten them when the inside end of whip starts to enter coil on stick you must trim it as it will effect tuning so trim as needed.
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KC2NYU
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« Reply #3 on: February 11, 2013, 01:23:52 PM »

Guys- thanks for both inputs.
- k5lxp -- great idea about using stiff wire to get an idea of length and then trim final singer. Yes I do have an antenna analyzer, so good there.

--   w8jx you said I have used Hamsticks for 20 years. When tuning them, as you shorten them when the inside end of whip starts to enter coil on stick you must trim it as it will effect tuning so trim as needed.----so if whip should not enter coil, can I just trim it to start so it will never enter the coil??

73 Paul
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W5DXP
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« Reply #4 on: February 11, 2013, 01:34:34 PM »

START: Stick the stinger into the Hamstick to within a couple of inches from the coil.
Test the resonant frequency.
IF the resonant frequency is too low
THEN chop one inch off the stinger and goto START
ELSE stop chopping and adjust the stinger to resonance.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
K2DC
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« Reply #5 on: February 12, 2013, 05:57:38 AM »

With the true Hamsticks, you had to be very careful not to run the whip too far into the shaft.  There is a wire (part of the loading coil) that crosses inside the shaft across the access hole for the whip.  You have to be careful not too cut that wire by running the whip too far into the shaft.  The suggestion to start with stiff wire is a great one.  That way you can trim to length from the top down, then cut the whip once to the correct length.  The whips are pretty stiff material and not easy to cut.

GL & 73,

Don, K2DC
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KE3WD
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« Reply #6 on: February 12, 2013, 07:35:16 AM »

AND, you would be wise not to cut before finding out via SWR and Power indications where you are at first. 

Easy to cut, not so easy to add it back if cut too much.


73
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VE3FMC
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« Reply #7 on: February 12, 2013, 01:10:01 PM »

AND, you would be wise not to cut before finding out via SWR and Power indications where you are at first. 

Easy to cut, not so easy to add it back if cut too much.


73

As my late Father used to say "Measure twice, cut once"  Grin
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KC2NYU
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« Reply #8 on: February 12, 2013, 03:02:38 PM »

Ok guys a few more followup questions:

- So if whip is not  to enter the coil, why do they make them that long to begin with ?
- I took my first shot today at seeing where I am, with stingers extending out about 9 1/2 inches on both Hamsticks, but not in past coil, SWR was on average 2.0
- On 20M, what should I be shooting for as far as minimum  SWR -- 1.5 or less?
- Anyone had one of these Hamstick rotatable dipoles for 20M?  How much of stinger extended from the shaft?  9", 8"  or what ?
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KB2WIG
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« Reply #9 on: February 12, 2013, 04:26:58 PM »

- So if whip is not  to enter the coil, why do they make them that long to begin with ?

Just so we're on the same page.

How long is the 'stinger' by itself? How long is one stick with the 'stinger' attached?

After you put both of the sticks together, does it look something like this?

http://kb1ccj.files.wordpress.com/2012/04/hamstick-dipole.jpg

The stingers look like they extend a lot more than 9 or 10 inches.


klc
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KQ6Q
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« Reply #10 on: February 12, 2013, 08:07:13 PM »

the photo is a hamstick dipole, but probably for 80m. I have one for 40, as a permanent installation on a mast. The short stinger advice may have been due to other things affecting the installation. Measure and tune, tune again, don't cut early! If you don't have a lot of height, feed impedance may be other than 50 ohms, so 2.0 SWR may be all you get. I feed my 40m hamstick dipole off a 25 ohm port on an un-un.
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KC2NYU
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« Reply #11 on: February 13, 2013, 04:28:53 AM »

How long is the 'stinger' by itself? How long is one stick with the 'stinger' attached?

-----the stingers are 48" when out of the shaft.

After you put both of the sticks together, does it look something like this?

---- Yes the whole rig looks exactly like that.

http://kb1ccj.files.wordpress.com/2012/04/hamstick-dipole.jpg

The stingers look like they extend a lot more than 9 or 10 inches.
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W5DXP
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« Reply #12 on: February 13, 2013, 05:34:04 AM »

If you don't have a lot of height, feed impedance may be other than 50 ohms, so 2.0 SWR may be all you get.

In addition to height, inductive loading can decrease the resonant feedpoint impedance (especially for high-Q coils). A shunt cap across the feedpoint can twist the feedpoint impedance closer to 50 ohms (while raising the resonant frequency). Something around 300 pf should do it for a 40m hamstick dipole.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
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