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Support > Q & A
Common Q&A for Temwell Helical Band Pass Filter

Q1: What・s the difference among 7H.7S.5W.5R Series?

Case name

 Tuning Pole

Case size

H x W (mm)

Terminator Freq. Region Input power

7H series

2-5 Pole 12.5 x 7.6 Pin type 42~1500MHz >1 watts
7S series 2-4 Pole 7.7 x 7.6 Pin type 196~1500MHz >1 watts
5W series 2-4 Pole 8.6 x 5.6 Pin type 230~2600MHz >1 watts
5R series 2-4 Pole 8.6 x 5.6 Pin type 230~1650MHz >1 watts
Q2: What・s the difference among 7H2.7H3.7H4.7H5 ?
Differences \ Item 7H2 (TD) 7H3 (TT) 7H4 (TF) 7H5 (TV)
 In the Dimension Double-tuned Triple-tuned Quadruple-tuned Quintuple-tuned
 In the Performance

 Each Series adding one pole itself will increase attenuation and offer much better 

 performance. Also, it・ll increase Insertion Loss 10~30% from the original one.

Q3: How to choose a Part Number from Temwell Standard Product List?

Please follow the below steps:

1.Decide Center Frequency you need, searching it from .・Acceptable Specify Fo Range・・ (designed by  

   Temwell), then you can minimize the area and focus on some specific Parts Numbers.

2.Select the close Spec which could fit your Bandwidth, Insertion loss and Attenuation need.

3.Click onto each Part Number in the data-sheet, see the Performance curve and detail Spec.

4.Find out the best Performance Curve that close your request in each Data-sheet.

5.Choosing the Part Number that have the closest spec to you.

6.If the Sample Fo of your selective Part Number doesn・t completely meet your requests, please ask us 

   to make the custom item as your need, providing us Center Fo, BW, IL, etc in the same time.

Q4: What do you mean by .・Acceptable Specify Fo Range・・ showing on each Spec.?
A4: That means we can make the same performance curve shift as the Frequency range that we set in the acceptable specify Fo Range. For example, Part Number:TT6755D-145M, Acceptable Specify Fo Range:125~145 MHz, customer need Fo=127 MHz, It・s because Fo=127M during the range 125~145Mhz so that the specification and performance curve of TT6755D can be tuned by Temwell to 127MHz as good as the original Fo. The Part No. would be transferred to TT6755D-127M .
Q5: What do you mean by .・Tunable Range・・ showing on each spec., can I tune by myself?

1.Tunable Range +/-10 MHz means you can tune by yourself, in this case, performance will not move 

   so much, however, only when you need to make some necessary modification to adjust your equipment,

   please noted you should have instrument such as network analyzer, then tuning the Fo about +/-10 MHz

   is acceptable. (^Please noted we are not responsible for the tuning damage caused by customer)

2.7H4 Series (TF) and 7H5(TV) are  not allowed to tune by customers themselves.

Q6:  In what situation should I do some .・Tuning・・ by myself?

 In some particular cases, it is very important to tune by yourself. If match circuit don・t complete (in or out ),

 with RF Circuit. So that Fo (Center Freq.) would be moved in a several MHz from Fo. At this moment, you

 can tune the screw very carefully , let Fo return to original Fo that you design at the beginning.

Q7:  What do you mean by .・Bandwidth・・?

 The width of the pass band of a Band Pass Filter is the frequency difference between lower and upper 

 3 dB points, Generally ,show at V3db,sometimes,at V1db it described the same spec of curve at different

 mark point .

Q8: What should I note if I will adjust the screw by myself?
A8: When you want to tune the screw. Each screw moves the same distance and see the Band Pass figures by NA. If someone is overturning and lose the function, please be responsible for the unworking BandPass Filter.
Q9: Low pass, high pass, and band pass?

 Low pass and high pass are not available. We only provide BAND PASS FILTER, which means a filter that

 passes one band of frequency and rejects both higher and lower frequencies.

Q10: How many types of pin position for options?

 There are total 6 types in each Temwell Product Series such as  A. B. C. D. E. F. The detail Pin Position

 Diagram as the following connect.  TEMWELL PIN POSITION DIAGRAM

Q11: Where is the different between RF Connector Filter and RF Band Pass Filter?

 It's different between RF Connector filter and RF Helical Band Pass Filter because the RF Connector filter have combined the RF Helical Filter(7H3 and 5W3 Pin Type Series) with the PC board with the connector, 

including SMA,F,N, and we have already adjusted the efficiency. If you are not sure to use the Helical 

Filter into the PC board ,we would recommend you purchasing the RF Connector filter ,which can be 

used by locking the connector .

Q12:  What .s the difference between Saw Filter and Helical Band Pass Filter?
@ Helical BP Filter Saw Filter
Center Frequency (Fo.)

Fo = 44~2600MHz

(Accept Customized Fo.)

Fo = Fixed Freq. only

(Each Freq. needs a New mask)

Band Width (B.W.)


 B.W.= 2~250MHz

(Accept Customized BW)


 B.W.=0.1MHz UP Only

(Fixed  B.W.)

Initial Charge USD120~200 per item

Thousands USD per mask  

Insertion Loss


IL=1.0 ~ 8.0 dB

PS. The more BW, the less IL

about 0.5 dB

(If your match circuit is great,
the I.L. would be <1.0dB Loss.)

IL=3 ~ 30 dB

PS. The more BW, the more IL

about >10~20 dB

Impedance  50 Ohms / 75 Ohms  500 ~ 2K Ohms



Sample  7~10 Work Days  60~90 Days
Mass Prod  35~45 Work Days  60~90 Days
Q'ty Limited

 Min. order 

10 PCS


Several Thousands of PCS

In-put Power

1~4 Watts 

(depend on frequency)

 <0.2 Watts


Case Type

Pin Type

7H/ 7S/ 5W/ 5R/

 SMD Type 


Q13: How to make calibration?
A13: (1)Diagram for NA ( Network Analyzer)
(2)Match to 50[ diagram
Q14: How to Tuning to your Fo?

 The Tuning Steps:

1.Preparing the  PCB + SMA Connector as Test Fixture.

2.Processing the Calibration test as attached drawing.

3.Turning the both right & left screw with the same direction, distance & time. The curve will shift the

    center Fo from the one to the other you want. 



 For example: 

 you can drive both right & left screw to the left side each 0.5mm simultaneous, until you saw 

 the NA reached at 895MHz.  When the performance S11 & S22 is the best & Return Loss is 

 the biggest.   A perfect performance is finished. (N/A: Network Analyzer)





The Expert of the RF Band Pass Filter design& manufacturer, RF Diplexer &Duplexer, RF 50 ohm& 75ohm Filter, RF Tunable Filter


Temwell Corporation / Temstron Co., Ltd.

   8F-1,No.51, Sec.1,Min Sheng E. Rd.,Taipei, Taiwan    Tel:886-2-25652500 ( 7 Line )    Fax: 886-2-25515250  /  886-2-25652287    

E-Mail :  sales@temwell.com.tw 

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