bg1jaa

这几天想买个817看宣传上拉个电线就能当天线,着东西方便携带,容易调试,就是不知道那里有卖或这么做一个?
谁知道给说说?
http://www.hellocq.com/member/attac...37637&type=.jpg
http://www.hellocq.com/member/attac...37627&type=.jpg

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守听437.900

火腿蛋

差不多长的线加个小天调

__________________
Bd5QCE
拉伊拉哈伊拉拉 莫汉姆扽拉斯如拉

我是坑大挖喜欢挖大坑

我的食量让人可怜（一斤面就顶两小时）
我爱喝酒让人害怕（有酒必喝有喝必醉）

我们要发扬一不怕苦二不怕死三不要脸的精神想尽办法坚定不移大刀阔斧不遗余力专心致志的把这个世界搞乱！！！

纯外行

俺用这个，感觉还不错！携带方便！！！

上传的图像

    

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姓名 陈文革
呼号 BG4JFJ
电话 13869168607
地址 山东建筑大学理学院
　　　　济南市临港开发区凤鸣路
　　　BG4JFJ@YAHOO.COM.CN
邮编 250１01

BD1IOY

找到好图了！

Musings on the Miracle Whip design




A front view of the finished design.




Introduction
The 'Miracle Whip' design is of interest to people wishing to have a small footprint portable setup. However, looking at the original design published in QST in 2001, it is clear that the rheostat auto transformer design, while innovative, is a stumbling block to home construction of the antenna. It is also self evident that it is difficult to build since the commercial design uses an entirely different approach.

As I said, the autotransformer approach to matching the short whip to the transmitter is innovative, if not original. I looked at this concept and decided that it could be mechanically simplified if the user was to accept two controls, one for coarse tuning, the other for fine tuning. This is the basis of the modified design presented here.

Rather than building a transformer with a tap at each turn, this design relies on a transformer which has one tap per turn for the first four turns, a tap every fourth turn for forty-eight turns and then another four turns tapped each turn. The coarse 12 pole tuning switch is connected to the twelve four turn taps. For the fine tuning a dual ganged 4 pole switch is connected to both the top and the bottom tapped sections.

The design should be easy to duplicate, I have used no specialist parts and takes about an afternoon to put together. The cost, in the UK, was around £10 with components purchased from Maplin, and could be less if you have a well stocked junk box!

Schematic


The twelve position switch on the lefthand side sets the coarse tuning and
the ganged switch on the righthand side provides the fine tuning


What you will need
1.31 Metre (50 inch) telescopic whip antenna
Rubber grommet to suit whip
Project Box 143L by 82W by 44H
12 pole 1 way rotary switch
4 Pole 3 way rotary switch
F114-61 toroid
1.3 Metres of 24 SWG copper wire
Small sheet of fibreglass PCB material
BNC Connector, chassis mounting
M4 screw to fit whip
Knobs to fit switches

Construction



This picture shows the inside of the Whip, this the unit lying on its side.
In the bottom lefthand corner is the coarse tuning switch with the toroid mounted on top.
In the centre is the fine tuning switch and to the right is the BNC connector.
Also note the use of PCB material for a baseplate.

The toroid




This picture shows a closeup of the toroid with the taps clearly visible


The toroid is wound on an F114-61 core, winding it is a little time consuming and also tough on the fingers. You will need about four feet of copper wire, I used 24 SWG. I have found that is is best to fold the wire in half and start at the centre of the winding. This gives a shorter length of wire to handle, but makes it more difficult to keep track of the turns!

The toroid should have a total of 56 turns once you have finished. There should be a tap after the first, second and third turns, then a tap every four turns until you have made twelve four turn taps and then a further four turns with a tap each turn. it is best if the first and last four taps come out radially from the toroid and the twelve taps for the coarse tuning from the top, as shown in the picture above.



The toroid mounted on the coarse tuning switch.
Note the radial taps in the bottom lefthand corner.



The next job is to solder the toroid to the coarse tuning switch, once finished, it should look similar to the picture above.

Mounting the Whip




The bottom of the whip mounted onto the PCB material
Note that the copper is cut around the screw hole to prevent a short to ground.

The Whip I used required an M4 mounting screw which I soldered to a piece of PCB material. I used the edge of a file to clear the copper around the mounting point to prevent a short to ground, this is clearly visible in the picture above. At the top of the case (not shown), I drilled a hole for the whip and used a rubber grommet for neatness.


Putting it together
I have not gone into the finer details of drilling and mounting the switches or the BNC connector. From the pictures you can get an idea of the positioning, but I will leave it to you to fine tune the ergomonics of your copy of the design! Once the hardware is bolted down, connect up the remaining connections with hookup wire.

Operation
Operating this design is similar to the original 'Miracle Whip' design. Once you have selected the band on the FT817, set the fine tuning control to position two or three and rotate the coarse tuning control to achieve the highest background noise, or the strongest signal if you are listening to a station. Next key the rig and use the fine tune control to achieve the lowest SWR. You may find it is necessary to move the coarse tuning a position either way to optimise the SWR reading. Once you have the lowest SWR, note down the settings so that you can quickly QSY to the band again.

It is important to note that this design is only suitable for power levels up to about 10 Watts.

Performance
The whip described here will tune up to a respectable SWR on 40 metres and up.

Much has been said about the performance of the 'Miracle Whip' design, but at the end of the day a 48 inch whip is going to be hard pressed to beat most other antennas. My experience is that it does not come close to the performance of the loop antenna's to be found on this site. However, when the bands are in good shape you will make QSO's. During the testing of the design, I work an OK1 on 15 metres (a distance of about 700 miles) for a 439 report, I gave him 559 in exchange. We were both running 5 Watts QRP. Later, on 30 metres, I worked a PA3 who gave me 449 to his 589, again both QRP.

If you have any questions, suggestions or good experiences with the antenna, drop me an email, I will be interested to hear your successes.

__________________
NAME: 崔旸
CALL : BD1IOY/QRP　
GRID : OM89ew

Considerate Loyal Progressive Friendly Balanced Patriotic

BD1IOY

Ten Dollar Miracle Whip Clone





I bought a 6 foot whip and 25 ohm rheostat at radio shack and wired them up like this:



----
\ / 6 foot whip
\/
|
|
\
/
rf in ----->\ 25 ohm radio shack rheostat
/
\
|
---
/// gnd





I did some experiments with it ( off a quarter mile with my xyl reading base rig
s=meter back over 2 meters).

__________________
NAME: 崔旸
CALL : BD1IOY/QRP　
GRID : OM89ew

Considerate Loyal Progressive Friendly Balanced Patriotic

BD1IOY

__________________
NAME: 崔旸
CALL : BD1IOY/QRP　
GRID : OM89ew

Considerate Loyal Progressive Friendly Balanced Patriotic

bg1jaa

大哥你们弄的都他复杂了,能不能弄个线差上就能用呀?

__________________
野外专业装备www.exone.net
24小时热线:13391733089
呼号BG1JAA
守听437.900

bg1len

除了波段开关就是线圈

__________________
BG1LEN
bg1len@126.com
adobe用户基地

bg1jaa

http://www.hellocq.com/member/topic...c=126667&show=0
这个有人用过么?

__________________
野外专业装备www.exone.net
24小时热线:13391733089
呼号BG1JAA
守听437.900

bg1jaa

自己顶一下

__________________
野外专业装备www.exone.net
24小时热线:13391733089
呼号BG1JAA
守听437.900

BG7.KIL

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BG7.KIL

想偷偷的把对方的摄像头打开么?想看看心仪很久的她或他(她)的尊容么?
我为大家推荐一款远程视频强制侦探软件!国内首创,免费体验!
不相信的,你可以看下真人视频!
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7600

楼上的能把软件传上来吗？

VM58

按3楼的方法做吧，买个自动天调（可以放在天线的下端），就简单了，效果也不错。4楼帖子原理上效率要高一些，不过图片的做法DIY的能力像是刚毕业的所为，不把握。

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呼号：BG2RWR
TEL:139-984-80725
QQ:821442521
E_mail:v58-AT-tom.com
QTH:大连