S21 Comparison KC901H VNWA 3E NWT500 動態區間 Dynamic Range KC901H VNWA 3E NWT500 評比

S21 Comparison between KC901H  VNWA 3E  NWT500

S21 動態區間 (Dynamic Range) KC901H  VNWA 3E  NWT500 大評比

之前測雙工器, 三個儀器測出的曲線不大一樣,
這次用 " 固定衰減器 " 組合成 -20dB ~ -106dB 測三個儀器來個 PK 評比一下:

衰減器是 MACOM DC - 4GHz 1-2W  -40dB 二個, -20dB, 與 -6dB (剛好沒有 -10dB)
組合成 -20dB, -40dB, -46dB, -60dB, -66dB, -80dB, -100dB, 與 -106dB 測三個儀器的 S21曲線

測量頻率:
NWT500   50KHz - 505MHz
VNWA 3E  1KHz - 505MHz
KC901H   100KHz - 505MHz

NWT500

NWT500   50KHz - 505MHz

看來 NWT500 在 -60dB 以下就不大準了!
不過以它的價格而言, 我認為已算是性價比相當好的儀器了!
73


VNWA 3E

已做好校正 (Full Calibration, Master Calibration Activated)

VNWA 3E  1KHz - 505MHz

另我訝異的是 VNWA 3E 在 -60dB 以下也是不大準的!
而且在 300MHz 有一個不連續切換
大致上, 在 UHF 約有 -3dB 左右偏低
到了 -80dB 以下原則上是不行的! ! !
上圖是圖片軟體剪接, 所以 -60dB -66dB 顏色較淡, 另看下圖:

-60dB -66dB 不怎麼好

-80db -100dB 很差

很訝異...
73


KC901H   100KHz - 505MHz

0dB

-20dB

-40dB

-60dB

-80dB

-100dB

-106dB

PK

三個儀器測出的曲線與數據看來,

KC901H 大獲全勝!

無論是 0dB 至 -106dB 動態區間的線性度,
或是 100KHz 至 505MHz 頻率區間的波動, 都是最好的!

以上是測試結果

73 de BM2CAJ



Dear BM2CAJ,
OK, I will take time to check the VNWA3 in my side. It using the alias mixing for working to 1.3GHz with some performance degrade in higher band. In your testing frequency range, I am also wonder why it not work so good.
If I can't find good explanation to the result after doing the experiment, I will pass my doubt to DG8SAQ and see his feedback.
ps. For the attenuation test, I will do the same experiment with HP8753E in my side.

73,
de bx3aaq


Dear BX3AAQ

Thank you very much for the comment.
But don't worry. I will not regret to buy VNWA 3E. It is still a very good instrument for me.
It has lower power output level -27dBm. I guess this will be much better for pre-amp measurement,
which will be the next step for me. I played these instruments a lot. For the next step,
I hope to find time to make and test pre-amps.

Thank you very much!
73 de BM2CAJ



左岸 BG8AAS 給了一些評論, 有興趣的 OM 可以看看:
http://www.hellocq.net/forum/read.php?tid=309797

8樓 ...
73



Dear BM2CAJ,
The HP8753E measurement for attenuator are shown(import and display with VNWA software)
1. Attenuator in 0/-20/-40/-60/-80/-110 dB

2. Attenuator in 0/-20/-40/-60/-80/-110 dB with data smooth average(same dataset as above)

It reflects some some information here
1. In the lower attenuation test, the measurement difference is below about 1dB
2. In the higher attenuation test(attenuator set to 110db), the measurement difference is quite large and the signal is fluctuated
3. With smooth average the measured data, the measurement difference is narrow down, but it also lost the detail of the result.
I am quite impressed the KC901H to get the -120dB attenuator measurement. The isolation for cable, connector and PCB board will not reach that level easily. Maybe it can also do good as a SDR frontend!!
73,
de bx3aaq


Dear BX3AAQ,

感謝您的分享, 能見到專業儀器的測試, 真是高興! 漂亮極了!
比較之後, 看來 KC901H 的 S21 滿不錯的!

但我發現用 50 歐姆假負載測 S11
KC901H 與 VNWA 3E 的曲線都沒有很完美, 或 許 電橋不容易做完美?
一直猶豫要不要 po 出來...

如果你的時間 許 可, 再請你也測一下, 謝謝!

73,
de BM2CAJ
2013-1-29


2012-08-21
2013-01-29
2020-07-31 revised