To start this topic I'm re-posting some HT antenna test results from another thread.
Earlier I compared the stock 7" Yaesu duck, the Nagoya NA771 ($7-$14 on eBay) and my Ed Fong shirt-pocket roll-up J-pole (http://www.eham.net/reviews/detail/6376). The J-pole was 7' up in a tree branch. Originally I wanted to see if the 15.5" Nagoya was better than the 7" Yaesu duck. The 2 performed identically. This time I added a rat tail to the HT's antenna to see its affect.
For a rat tail I cut a piece of 22AWG stranded, insulated wire to 19.5" and stripped 1". I wrapped the 1" of bare wire and around the SMA connector before screwing the antenna on. In use I made sure it hung down.
I went outside during the Sunday pm 2M nets and compared Rx readings. Here's the S-meter results from a somewhat distant 2M repeater:
ANTENNA NO RAT WITH RAT
Yaesu S5 S8 to S9+20
Nagoya S5 S8 to S9+20
J-pole S8
With the rat there was a bit more sensitivity to where I stood (S-meter moving up and down as I walked around), but wholy-cow, what a difference. All I can say is that I'm a rat tail convert. That magic little piece of wire is now in my HT travel bag.
Are those SMA type connectors? How did you connect the rat tail? What length. 19" ?
Thanks,
Gil.
Yes, SMA. 19.5" of wire (before stripping). I just stripped 1" and wrapped it around the base before screwing the antenna on. I suppose for long term use I should do something more elegant, like ring lug.
Thanks Bob :)
Bob,
Good info, The 1/4 wavelength ground radial helps, as a counter-poise on a hf station or a rat-tail on a HT. Be sure and keep your SMA or BNC connectors clean. Do not over tighten SMA connectors. The rated torque for SMA connectors is 10oz/in. Guess I am old fashion, I still prefer the BNC connector. It easier to add the rat-tail to a BNC connector.
Take Care, 73'S KA5SIW
Guess I'll have to stop grabbing my HT by the antenna ::)
Gil.
Quote from: cockpitbob on December 02, 2012, 10:45:36 PM
I suppose for long term use I should do something more elegant, like ring lug.
Elegance plus good effect is a killer combination. Thanks for your rattail info, I will be trying it.
I added a 19' rat tail to my Yaesu FT-270R.
One word: WAOH!
BIG improvement..
Half bars to full bars S9+.
Gil.
Hi guys,
Interesting experiment. When executing this test, were you holding the HT or was it sitting isolated from your body?
Geoff
QuoteInteresting experiment. When executing this test, were you holding the HT or was it sitting isolated from your body?
Holding it, the rat tail dangling over the back of my hand..
Gil.
Quote from: gil on January 27, 2013, 10:41:23 AM
QuoteInteresting experiment. When executing this test, were you holding the HT or was it sitting isolated from your body?
Holding it, the rat tail dangling over the back of my hand..
Gil.
Ditto. Real world/use situation.
My HT carry bag will never be without a rat tail. Once I find a local 70cm net I'm going to first try it with tail cut for 70cm, then try it with a 2M and 70cm connected at the same time. It works for fan dipoles so it probably would work with rat tails. Then I wouldn't have to think about changing tails if I change bands.
Mine stays on now at all times.. Makes a huge difference.
Gil.
I'm thinking about it during a boring portion of a sales meeting...
Where is my thinking wrong considering the rat tail set-up as a 2m dipole?
QuoteWhere is my thinking wrong considering the rat tail set-up as a 2m dipole?
Pretty much...
Gil.
Anyone ever used a "thru the window" coax jumper (feed line comes into the window, jumper has coax connectors on both sides, connect outside portion to the coax, the jumper is flat with copper wires enclosed/encased, then an aluminum window is lowered and locked, then the 3' coax jumper is connected between the "inside" portion of the "thru the window" connector and the radio) with an HF antenna?
It's getting cold outside and the Frau has lost the desire to put up with the coax coming through a semi-opened window...and will NOT approve of a plan to drill thought "her" wall.
I don't mind drilling though the wall anyway...but I wondered if the the "thru the window" jumper might not help to avert a conflagration...
For glass mounts, I've considered them myself. I currently use a magmount dualband Larson which is a 1/2 wave centerloaded on 2M, 5/8 colinear for 440. A Larson NMO 2/70B, the one with the spring coil in the middle. Does pretty good. Have one tucked in each vehicle.
I use a magmount, which is admittedly a compromise mount, considering the capacitive coupling that provides grounding. Should drill the hole and be done with it, but it's been hard to get to that point on mine, and wife doesn't want a hole on hers, and the magmount does work. I feed it thru a side door, tucked between the door weatherstrip and body, entering the vehicle fairly low, haven't had any problems with water entry, or pinched coax this way.
Larsen has the same antenna with a glass mount.
Base spec of the antenna: Gain: 1.6/3.5 dBd
I have seen reports of good results with the thru glass one, I have heard others complain of the thumping and banging when they hit trees. Dunno.
The larsen thru glass p/n: KG 2/70CXPL
Gain: 0/2dBd
The spec attributed about a 1.5dbd or so drop over the base antenna. I suspect I get about the same attenuation with the magmount.
I went and did some research, here is an interesting link, that implies no, seems he doesn't like passivated glass as a thru mount.
http://www.k0bg.com/antmount.html#glass
Cost of the thru mount is almost twice what the magmount was. Probably the main stumble point for me for trying it.
Also, with the magmount, I can use my 2M 5/8 wave antenna, also NMO base. It loads up on 6Meters also :).
Or remove the antenna altogether, if I want to escape being noticed. Or use an antenna on wife's jeep ;)
Not exactly what you asked for, I know, but were points for my consideration, thought I'd share.
Underhill
Wonder if the window jumpers would work for HF?
How would I make my own glass mount transformer?
Gil.
Quote from: cockpitbob on December 02, 2012, 10:28:20 PM
To start this topic I'm re-posting some HT antenna test results from another thread.
Earlier I compared the stock 7" Yaesu duck, the Nagoya NA771 ($7-$14 on eBay) and my Ed Fong shirt-pocket roll-up J-pole (http://www.eham.net/reviews/detail/6376). The J-pole was 7' up in a tree branch. Originally I wanted to see if the 15.5" Nagoya was better than the 7" Yaesu duck. The 2 performed identically. This time I added a rat tail to the HT's antenna to see its affect.
For a rat tail I cut a piece of 22AWG stranded, insulated wire to 19.5" and stripped 1". I wrapped the 1" of bare wire and around the SMA connector before screwing the antenna on. In use I made sure it hung down.
I went outside during the Sunday pm 2M nets and compared Rx readings. Here's the S-meter results from a somewhat distant 2M repeater:
ANTENNA NO RAT WITH RAT
Yaesu S5 S8 to S9+20
Nagoya S5 S8 to S9+20
J-pole S8
With the rat there was a bit more sensitivity to where I stood (S-meter moving up and down as I walked around), but wholy-cow, what a difference. All I can say is that I'm a rat tail convert. That magic little piece of wire is now in my HT travel bag.
Can you post a picture?
Quote from: Geek on February 15, 2013, 04:53:35 AM
Quote from: cockpitbob on December 02, 2012, 10:28:20 PM
To start this topic I'm re-posting some HT antenna test results from another thread.
Earlier I compared the stock 7" Yaesu duck, the Nagoya NA771 ($7-$14 on eBay) and my Ed Fong shirt-pocket roll-up J-pole (http://www.eham.net/reviews/detail/6376). The J-pole was 7' up in a tree branch. Originally I wanted to see if the 15.5" Nagoya was better than the 7" Yaesu duck. The 2 performed identically. This time I added a rat tail to the HT's antenna to see its affect.
For a rat tail I cut a piece of 22AWG stranded, insulated wire to 19.5" and stripped 1". I wrapped the 1" of bare wire and around the SMA connector before screwing the antenna on. In use I made sure it hung down.
I went outside during the Sunday pm 2M nets and compared Rx readings. Here's the S-meter results from a somewhat distant 2M repeater:
ANTENNA NO RAT WITH RAT
Yaesu S5 S8 to S9+20
Nagoya S5 S8 to S9+20
J-pole S8
With the rat there was a bit more sensitivity to where I stood (S-meter moving up and down as I walked around), but wholy-cow, what a difference. All I can say is that I'm a rat tail convert. That magic little piece of wire is now in my HT travel bag.
Can you post a picture?
Here's another site that has an article about the rat-tail, and he has some pics on there.
http://brainbender.blogspot.com/2007/09/2-meter-vhf-ht-handheld-ground-plane.html
Hmm, he says 20.5" and I use 19.5". Insulation on the wire(vs. bare wire) will slow the wave down a few percent, meaning the wire should be a few percent shorter. I picked 19.5" just by connecting a piece of wire to my MFJ antenna analyzer set to 146MHz and I kept trimming until I got a peak.
I'm almost certainly getting too picky, but when I get time I'll try it a different way. I'll connect a long wire and go outside during a locan 2M net and keep trimming it until the S-meter gives me a peak.
Hello,
Can you use the same 19.5" rat tail with a dual band 2m/70cm HT?
Gil.
Quote from: gil on September 07, 2013, 04:43:21 PM
Hello,
Can you use the same 19.5" rat tail with a dual band 2m/70cm HT?
Gil.
Very good question and I've been intending to test that for a long time. My guess is yes. On 2M the tail is 1/4 wave long and on 70cm it will be 3/4 wave long. You can always ignore half and whole waves leaving the tail looking like 1/4wave on 70cm. I've never played on 70cm (much to my shame). But the next 70cm net I find I can hit I'll do the before/after testing.
Bob
Well, if all goes well I should have a graphical antenna analyser within two weeks, now that would be interesting... I'd make say a 24" rat tail and cut half an inch at the time and look at the graph...
Gil.
That should be fun and possibly enlightening. Keep us posted.
I looked at my MFJ-259 analyzer and figured it was bigger than my HT, but what th hell. So, I put the HT's antenna on it, attached a long tail and started cutting the tail. I think my final length was 18.5". It was insulated wire and they tend to be a few % shorter than bare. Unfortunately my analyzer won't do 70cm frequencies.
Ah darn, yes, the one I'm getting goes to 200MHz, so we'll know only for 2m. Didn't think of that... :-[
Gil.
As far as going through a window with coax, why not make a false window. Get ya a 2X4 and make a frame. Sandwich insulation in it between two piece of plywood on the 2X4 frame. Make it to fit the window and snug the window down on your framework. You can then punch holes to suit yourself and the wife will be happy with it no doubt. Paint it and she will not even see it I bet. I once use a 2X4 sitting on the window seal and simply closed the window on it. I kept the window snug by wedging a piece wood to the top of the window and thus it became snug on the bottom 2X4 also. Use a short section of plastic pipe through this false window and bring lots of coax cable through it neatly. I used electrical putty around the plastic pipe for a no insect entry point and no rain water to get in either. It is more fun just to drill holes in the house though. Ha ha.
Quote from: cockpitbob on December 02, 2012, 10:28:20 PM
To start this topic I'm re-posting some HT antenna test results from another thread.
Earlier I compared the stock 7" Yaesu duck, the Nagoya NA771 ($7-$14 on eBay) and my Ed Fong shirt-pocket roll-up J-pole (http://www.eham.net/reviews/detail/6376). The J-pole was 7' up in a tree branch. Originally I wanted to see if the 15.5" Nagoya was better than the 7" Yaesu duck. The 2 performed identically. This time I added a rat tail to the HT's antenna to see its affect.
For a rat tail I cut a piece of 22AWG stranded, insulated wire to 19.5" and stripped 1". I wrapped the 1" of bare wire and around the SMA connector before screwing the antenna on. In use I made sure it hung down.
I went outside during the Sunday pm 2M nets and compared Rx readings. Here's the S-meter results from a somewhat distant 2M repeater:
ANTENNA NO RAT WITH RAT
Yaesu S5 S8 to S9+20
Nagoya S5 S8 to S9+20
J-pole S8
With the rat there was a bit more sensitivity to where I stood (S-meter moving up and down as I walked around), but wholy-cow, what a difference. All I can say is that I'm a rat tail convert. That magic little piece of wire is now in my HT travel bag.
TECHNICAL UPDATE:
Size Doesn't Matter (much)
I wanted to see how critical the length of the rat tail is. I put an extra long one on my HT during a local 2M repeater net and started cutting off 1/2" segments. Here's what the S-meter did as I shortened the rat:
LENGTH S-METER24" 5
23.5" 5
23" 6
22.5" 6
22" 7
21.5" 8
21" 8
' ' 8
17.5" 8
17" 8
16.5" 6
16" 6
13.5" 5 (got impatient and took a big cut)
0" 3
Conclusions:
1) Again the rat tail makes a BIG improvement. 5 S-units = 1,000:1 strength increase.
2) Length isn't very critical. I'm cutting all mine to 19".
The higher you can get the antenna the better. I like this guy's 2M man-portable antenna. If the coax is 19.5" long it will act as a rat tail too.
(http://i120.photobucket.com/albums/o170/cockpitbob/15803246_1e212da1d6_z_zpsr074j5om.jpg) (http://i120.photobucket.com/albums/o170/cockpitbob/15803246_1e212da1d6_z_zpsr074j5om.jpg)