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- Опубликовано: 13 сен 2021
- Episode 906
Let's try out a 35mm long antenna. Might not be working DX with it, but will it work?
Buy Nagoya 805: www.banggood.com/custlink/3mG...
NA-805
Frequency : 430-440 MHz
Gain : 0 dBi
Length : 4.5 cm
VSWR : Less 1.5:1
Impedance : 50 ohms
Connector : BNC/SMA Male/SMA Female
Made in Taiwan with RoHS Compliant
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8:52 Realistically, the only practical use for those stub antennas is to reach a hotspot inside the shack. So it doesn't matter if they radiate only a few milliwatts.
Interesting stuff, thanks! Enjoyed watching.
Those counterpoise people are going to be all in a tizzy after this, ha.
No, I guess not.
Many have found it useful in a regular rubber duck antenna.
After all it's nothing but a metal conductor of the right size making the other half of the dipole antenna oriented vertically.
Though not practical all the time its worth need not be questioned.
The principle behind the 1/4 lambda vertical is your hand forms the other half.
Here, IMSAI guy just touched the bottom of the "dummy Rx antenna" with a connector and expected a change in the pattern.
In the strict sense any antenna must be mounted in the "free space" using some kind of a stand and tested.
When he keeps moving his hand holding the contraption you can see the pattern getting affected and distorted.
He should have placed the marker on the "dips" to show the exact frequency of resonance.
De VU2RZA
Nice. Thank you
If you fill the antennas with liquid helium and then start a signal in them, they will run forever or so long as you maintain the liquid helium.
Surprisingly the Retevis RT-20 antennas on Amazon have a nice dip at 2m and 70cm. They are really quite good for their size and nice and flexible being silicone.
Do you have an more description for these antennas? Length? I've searched Amazon for Retevis RT-20 and came up with many radios RT-22, RT-24, but no RT-20. When I added antenna to the search I get a lot of antennas that say they fit RT-xx radios, but no RT-20.
@@BryanTorok Try Retevis RT20 antenna without the hyphen. Just measured 2 here. They are either 6.5CM or 7CM depending on male or female SMA. Yeah their numbering isn't great as a few products have the same name. I've tried a load of "Amazon" small antennas and these are the only ones that do what they say they do. I wouldn't be surprised if the Diamond and Nagoya antenna in this video are counterfeit. As all the clones/counterfeit antennas I've tested in that size are only resonant on 70CM. The genuine Diamond stubby antennas have capacitors in them so will show a dip on 2M and 70CM.
When you screw the two antennas together like that, does it make a repeater? (Seriously though, there used to be a passive UHF TV repeater near where live. Two very large horn antennas, constructed of sheet metal, one on either side of a ridge. It was in use for years. Maybe I'll hike up there some day and see if it's still there.)
Sounds interesting, I’ll love to see photos of that old repeater
How come Nagoya failed to mark the appropriate connector box on the lower left? Seems like that is attention to detail the real McCoya would ensure.
Can i use this nagoya antenna on my Boafeng UV-5Rh, 10W radio? And do i need to adjust settings when using this stubby antenna?
Don't forget to aim your tongue at the correct angle when making adjustments or measurements!
Then I might just get me a cheap knockoff if they are only meant to be used in a casual way, I need one of those for my *Baofeng GT3 Mark II* , the stock antenna is little too big for aesthetic reasons, and I only need it to communicate with my coworkers inside a building, they have the *Kenwood's TK3000* radios.
Well, if this is the real deal it seems no better than the knock offs trying to emulate them which mean they are all probably worth $1 and only then because the SMA is gold plated.
The new original Nagoya should be tri-band, why it resonates only at one frequency?
Because advertising hype is stronger than laboratory testing.
Of course adding the red clip lead didn't make any difference. You already have two counterpoises: the cable to the VNA, and your body. Add a few ferrite beads on the coax as close to the antenna as possible, and suspend the antenna with string, fishing line, or other nonconductive line. Then try it again. In normal use, the radio is the counterpoise, along with capacitive coupling to your hand.
Do you have a Signal Stick to test?
Nope