24 March 2015

Front-end saver for LB antennas

Hello,

If You are using a separate receive antennas, then you need a good protection circuit to eliminate the possibility of blowing out Your receiver's front-end while using these auxiliary receive antennas specially on low bands.


The protective circuit should be designed to disconnect the receive antenna during transmit, ground the receiver input when transmitting thus keeping RF out of your radio and eliminating the chance of blowing your radio's front end.



The perfect solution designed years ago Gary, KD9SV and I am using this genuine design in the alu-box for years without any problems.
Now I need more of these circuits because of more radios is planned in the ham-shack (SO2R etc.) and also the contest team OK5T need to improve the low bands setup...


Thanks to Martin's (OK1RR) great work I was able to use his slightly redesigned Front-end Saver based on KD9SV design using his PCB layout.


Very well-designed PCB with one-side bus wiring is easy to assemble and it will work for the first shot if you will not make the mistake...


The suggested PRMA 1A12 relays > molded rugged construction with internal protection diodes are used.

 
Steel painted box from local electronics shop is used in order to save building time and it does not look so bad.


Update 17July2017
There is not necessary to use the 2N2222A in metal TO-18 package! It is possible to use plastic TO-92 package as the most of parameters are same and there is not impact for that application. Most important is to identify the correct pin-out of your device!


There are several manufacturers producing several different versions like 2N2222A, P2N2222A, PN2222A etc. and the pin-out is NOT the same or standardized!


Check carefully your purchased version of transistors and identify the correct pin-out before you will assembly in order to avoid FES malfunction!
 

On picture above is an example of correct orientation of KSP2222A-E19 transistors TO-92 package on PCB...


After the final assembly I highly recommending testing the device for its correct functionality. It is much better to spend few minutes more instead of damaging your transceiver front-end stage because of non-working Front-end saver...

The short theory of relays operation in this circuit is here:

State nr. 1
(QSK T/R is floating)
Re1 - closed
Re2 - open
Re3 - open


In this case ANT port is connected to RCVR input port and AMP KEY port is floating.

State nr. 2

(QSK T/R is grounded)
Re1 - open
Re2 - closed
Re3 - closed


In this case ANT port is disconnected/floating, RCVR input port is grounded, and AMP KEY port is grounded too.



According to the theory of operation described above you can make easy and quick test using DMM before you will connect it to your radio and antenna.

1. Apply the 12V DC power to the circuit.

2. Check with DMM that ANT port hot pin is connected to RCVR IN port hot pin and that AMP KEY port hot pin is floating.

3. Using the tweezers or any similar tool short the hot pin of the QSK T/R port to ground.

4. Check that you are able to hear switching clicks of the relays when you are shorting the hot pin of the QSK T/R port to ground. Be very attentive as the chattering of relays is very quiet and fast so it is hard to hear in noisy environment. 

5. Check with DMM that in that state the ANT port hot pin is disconnected from the RCVR IN port (refer to point 2.) and it is floating. Then check that RCVR IN port hot pin is grounded. Finally check that AMP KEY port hot pin is grounded too. 


Update 18Sep2017
Some of the people asked me how to implement this FES into the Icom radios setup. So here is the layout example for wiring it together with Icom transceivers. (just quick pencil drawing...)


The "PTT output" port on the drawing means port on your transceiver where hot pin goes to ground while transmitting to control external equipment. In our case the FES. On the Icom radios this port is labeled as "SEND"!


See port 10 marked as SEND. This is your PTT for wiring it with FES.

The "Ext RX ant IN" on the drawing means port dedicated to connecting an external receiving antenna to your transceiver. On the Icom radios this port is marked as "RX ANT"! See port 1 marked as RX ANT on the Icom rear panel picture above.

Do not hesitate to ask for details if you need but all is clear from the pictures and circuit is pretty simple. Also let me know if you want to help with PCB or even with PRMA 1A12 relays for building your own FES...

With courtesy permission from Martin,
OK1RR


73 - Petr, OK1RP

Building document done by P. Ourednik, 20-Dec-2017. Document 12-17, rev.4.0

87 comments:

  1. This comment has been removed by a blog administrator.

    ReplyDelete
  2. Yes, PCB are still available as same as the PRMA relays.

    ReplyDelete
  3. New batch of fast PRMA relays and PCBs arrived. Kits are available again...

    ReplyDelete
    Replies
    1. Hi
      Can you please send me details of the kit.
      djcleckie@dive-boats.co.uk

      73
      Dave
      GM4NFI

      Delete
    2. Hi David,
      thank you for reply. I have sent the detailed information to your email already. 73 - Petr, OK1RP

      Delete
  4. Hi Petr. Great to hear a new patch just came in. I am interested in a Kit. Thanks, Matt K3WAZ

    ReplyDelete
  5. Hi Matt. Thanks for note. I have sent you an email with detailed informations already. 73 Petr OK1RP

    ReplyDelete
    Replies
    1. hi Petr,
      Could you send me info abt the kit..??TKS
      My email :ik2yra@gmail.com
      /3's Carlos

      Delete
  6. Hi Petr,
    Please send me the ordering information for the kit. My email address oh6xi@sral.fi
    Vy 73 de Ulf

    ReplyDelete
  7. Hi Ulf,
    Tnx. Yes I will send you more details Monday morning as I am out of home until Sunday nite. Best 73 Petr

    ReplyDelete
  8. Hi
    Can you please send me details of the kit.
    sv3ckz@gmail.com

    73 Akis SV1CKZ

    ReplyDelete
  9. Hello:
    Pls send ordering info for U.S.A.
    Thank you & 73, NN7DJ
    nn7dj@engineer.com

    ReplyDelete
  10. Hi, Could you please send me information on the kit too? Thank you!
    k2pjw@yahoo.com

    ReplyDelete
  11. Hi, upon several emails there is short intro for used relays. The PRMA 1A12 relays can not be replaced with any other cheap and slow relays! These relays have around 0.5ms switching/release time and it is the key parameter of this design! Do not try to replace them with standard slow relays without checking their switching time first. Remember that the FES must be fastest in the system to protect your RX...

    ReplyDelete
  12. Hi Petr,
    Please send me the ordering information for the kit. My email address gigi.yo7ne@gmail.com
    Vy 73 de GG

    ReplyDelete
  13. Hi Petr,
    Please send me the ordering information for the kit. My email is ei2kn@hotmail.com.Best 73 de EI2KN

    ReplyDelete
  14. Please send me the ordering info, if you still have availability.
    - Dan, W2DLC

    ReplyDelete
  15. Hi Dan, information has been sent to your email. Best regards,
    73 - Petr, OK1RP

    ReplyDelete
  16. Hi all,
    some people asked me by email if it is possible to use the 2N2222A transistors in plastic package instead of the metal one? Yes, it is ok to use them in the plastic package. I prefer the 2N2222A - (A) version with a little bit higher AMR. 73 - Petr, OK1RP

    ReplyDelete
  17. Great Job,
    Could you Please send me ordering info for the kit as well.
    Thanks,
    Larry, W4AVZ

    ReplyDelete
    Replies
    1. hi Larry. All info has been sent you by email. Thanks. Petr

      Delete
  18. Hi
    Can you please send me details of the kit.
    rayeckel@yahoo.com

    Thanks!

    ReplyDelete
  19. Hi peter,
    I am interested to order the kit. Can you please email me how to proceed?
    Thanks
    Vk2icw
    Vk2icw@gmail.com

    ReplyDelete
  20. Hi Peter,
    I am planning to build a front end protector. Can i know the availability of pcbs and relays please?
    Thank you & 73
    Manoj vu2cpl"at"gmail"dot"com

    ReplyDelete
    Replies
    1. Hi Manoj, the instructions has been sent to your email. 73 Petr OK1RP

      Delete
  21. Upon several emailed questions there I am confirming that there is not necessary to use the 2N2222A in metal TO-18 package! It is possible to use plastic TO-92 package as the most of parameters are same and there is not impact for that application. Most important is to identify the correct pin-out of your device! There is several manufacturers producing several different version like 2N2222A, P2N2222A, PN2222A etc. and the pin-out is NOT the same or standardized! Check carefully your purchased version of transistors and identify the correct pin-out before you will assembly in order to avoid FES malfunction! 73 - Petr, OK1RP

    ReplyDelete
  22. Hi Peter,

    I am interested in ordering the front end protector kit. My email address is: hermhalbach@centurylink.net.

    73

    Herm, KG7WMZ

    ReplyDelete
  23. Thank you, Petr, for your excellent service and rapid delivery.

    73

    Herm, KG7WMZ

    ReplyDelete
  24. Petr, I'd like to order a kit as well.

    Regards,

    KH6IO

    ReplyDelete
    Replies
    1. Jeff, please send me an email where I can send you more details about the saver and kit please. 73 - Petr, OK1RP

      Delete
    2. Jeff, I found some email address to you so I sent you details about the kit. Petr

      Delete
  25. Hi all, last batch of PRMA 1A12 relays arrived. It is the last batch because these relays are obsolete and no more pieces in supplier's stock available... Let me know if you want the PCB + 3pcs of PRMA relays kit for your own FES. 73 - Petr, OK1RP

    ReplyDelete
    Replies
    1. Will you please send ordering details?

      Will new kits be available with replacement relays?

      Tnx,

      -Steve
      w7wm@arrl.net

      Delete
  26. Hi all, this user guide above for building your own FES is updated for Icom wiring layout for now. Hope it helps. 73 - Petr, OK1RP

    ReplyDelete
  27. I am interested in ordering the front end protector kit. My email address is: ki3ttbob@gmail.com

    thanks
    Bob KI3TT

    ReplyDelete
  28. Good day
    I would like details for ordering your front end saver kit with board and relays if still available
    Thank you
    Joe
    KR0UT
    joekrout@yahoo.com

    ReplyDelete
  29. Hello, me too please - advise on ordering kits.
    Cheers Tom - G8PBJ@yahoo.com

    ReplyDelete
  30. This comment has been removed by the author.

    ReplyDelete
  31. hi Petr,
    Could you send me info abt the kit..??TKS
    My email :ik2yra@gmail.com
    /3's Carlos

    ReplyDelete
  32. Hello Petr,
    Kit info please: hdwright@gmail.com
    Tnx/73

    ReplyDelete
  33. Hi Petr,
    I am interested in ordering the front end protector kit.
    Please send me the ordering information for the kit.
    DE exJO1ABL JAPAN

    ReplyDelete
    Replies
    1. Hi JO1ABL, let me know email to send info. Petr

      Delete
    2. Hi Petr,
      I'm sorry to trouble you.
      My email :takahashi.masahiko@gmail.com
      DE exJO1ABL JAPAN

      Delete
  34. Hi Petr, do you still have boards and relays available? TNX es 73 Denis. discotom50@yahoo.co.uk

    ReplyDelete
  35. Hi Petr, Do you still have the board and relays available?
    73
    Clint
    W7KEC
    kiheiman@q.com

    ReplyDelete
  36. Hi,
    thanks for message regarding FES. Replied already off-list...
    Petr

    ReplyDelete
  37. Upon email question... yes, it works with OM3500 amplifier from OM Power. it is keying this amp. w/o any issues. 73 - Petr, OK1RP

    ReplyDelete
  38. Hi all, few weeks ago I got information from one of the builder that his FES made from parts purchased on eBay and home made PCB does not work as it should and the relay is much slower than it is stated in the datasheet. After several emails exchanged w/o finding the root-cause I sent him my own old relays from the junk and wow... it works properly for now. So be careful as it looks like counterfeit or fake issue in that case from eBay... 73 - Petr, OK1RP

    ReplyDelete
  39. Hi Petr,
    Please Can you send me details of kit priciing for UK delivery. Many thanks G4PDF - robert_copeland@btinternet.com

    ReplyDelete
  40. Hello Petr ,
    Can You please send me info about pricing for the kit( board ) .
    I need to put a FES on my ELAD FDM S2 @ remote rx qth where there are also some OM 3500 on the air sometimes .
    Tnx and best 73 ,

    Jim ON4DS ( former ON5UM ) ON4DS@telenet.be

    ReplyDelete
  41. Hi Petr, do you still have boards and relays. Are they available on eBay?
    TNX es 73 Kalle.
    Cebulon2000@gmx.de

    ReplyDelete
  42. Hi Petr, do you still have boards and relays available? Grateful for ordering information if so.
    dylikethat@gmail.com
    Best wishes,
    Martyn
    M1MCL

    ReplyDelete
  43. Hi Petr,
    Interested in the board and relays of the saver.
    Pse ordering information if applicable.

    Best wishes,

    Isaac 4Z1TL, tsachyl@gmail.com

    ReplyDelete
  44. Hi Petr,
    Please could you send me any ordering information for the board and components.
    73 from Jon/G4ZMM
    G4ZMM.JON@GMAIL.COM

    ReplyDelete
  45. Hi Petr,
    I would like to purchase your kit....could you please send me the necessary information so I can do so??
    Thank you very much! It looks like a great product! Congratulations!
    73!
    Peter
    KD2OMV
    pve@ncortho.com

    ReplyDelete
  46. This comment has been removed by a blog administrator.

    ReplyDelete
  47. Hi Petr.
    Would you please send information regarding purchase of this kit? Shipping to Texas.
    w5zym73@gmail.com
    73,
    Craig

    ReplyDelete
  48. Hello, Please send ordering details. posprovisions@gmail.com

    Thank you.

    ReplyDelete
  49. Hi Petr,
    Can you please send me ordering and payment information. I live in New Zealand
    Thank you and 73
    Graham Wilson
    ZL1CE
    email: grahamw@xtra.co.nz

    ReplyDelete
  50. This comment has been removed by the author.

    ReplyDelete
  51. Hi Petr,
    Please Can you send me details of kit pricing for Montevideo Uruguay delivery. Many thanks
    LALO
    cx3at@yahoo.com

    ReplyDelete
  52. Hello,
    Could you please send me details of kit availability and pricing for Poland?
    Thank you in advance,
    Michał,SP9WOL sp9wol@gmail.com

    ReplyDelete
  53. Hello Peter, Please send details for kit purchase. Thank you

    Frank K9IC K9IC.ARS@gmail.com

    ReplyDelete
  54. Hi Peter please send me the Kit purchasing info to Rome.
    73, Enzo, IK0AOC
    ik0aoc@gmail.com

    ReplyDelete
  55. Hi Peter please send me the Kit purchasing info .
    73, Damian, G1GWH
    g1gwhuk@gmail.com

    ReplyDelete
  56. Hi Peter, please send me the Kit purchasing info.
    Ed AD7GR

    ReplyDelete
  57. Hello Peter, please send me the Kit purchasing info too.
    Peter HB9BUN

    ReplyDelete
    Replies
    1. Peter, yes now available again. Appropriate relays arrived. Probably last batch of these hard to find parts. Drom me an email from QRZ.com

      Delete
  58. Hello Peter
    Is the kit still available.
    Thankyou

    ReplyDelete
  59. Hi Peter, please send me the Kit purchasing info.
    John VE3VGI

    ReplyDelete
    Replies
    1. John, still available. Drop me an email from QRZ.com

      Delete
  60. Peter, Are the kits still available? If so, how can I reach you to purchase?
    73,
    Brad, KA3YAN

    ReplyDelete
  61. Hi all, still parts and few PCBs available. Drop me an email. QRZ.com

    ReplyDelete
  62. Brian, your 2 sets of PCBs and relays shipped. Thanks.

    ReplyDelete