International Radio

Performance Enhancement Kits


Non Radio Specific

*Key Pulser
Click to EnlargeInternational Radio's Key Pulser is designed to key a transmitter at a predetermined duty cycle to allow tuning at a safe average power level. The heat generated in a radio (or radio plus amplifier) is determined by the average power being dissipated. This can be very high if tuning is done with the key down full time. By pulsing the key line the average power can be reduced by the duty cycle of the keyed waveform.

Our Key Pulser has a digital circuit, which provides an accurately controlled duty cycle that is adjustable from 20% to 100% in steps of 10%. The pulse repetition rate is approximately 50 milliseconds. This is like a train of dots at about 48 WPM.

Specifications:
  • Operating Frequency: 20 Hz (48 WPM)
  • Output pulse duty cycle: Adjustable from 20 to 100% in 10% steps.
  • Maximum keyed voltage: 40 Volts
  • Maximum keyed current: 200 mA.
  • Battery current drain: 300 micro Amperes
  • Battery life, operating: Greater than 1500 hours.

Click Here to order.


YAESU

*Yaesu FT-847 VOX Box
CLICK TO ENLARGEIt's a great little radio, but no VOX! So we're making one. This is a separate box, powered from the radio Microphone jack. It has an 8-pin connector on the back for a Yaesu microphone. It has a mini phone jack on the front for a Heil microphone. Controls are provided for Gain, Delay, and Anti Vox. Yes, it will work with other rigs that don't have VOX. Click Here to order.


*Yaesu FT-920 Filter Switch Board
Click to enlargeThe FT-920 Switch Board allows the use of one filter or two in cascade. The switching is done by a mini toggle switch mounted on an L bracket under a screw in the bottom cover. Two of these boards may be mounted in the FT-920, providing filter selection from one switch for both CW and SSB. The boards are supplied pre-wired so the customer need do only a minimum of soldering. Click here to order!


Click to EnlargeOne early customer of this mod wrote the following (unsolicited!) review:

"...the resulting performance improvement in the radio is dramatic... The two filters in cascade create an improvement in selectivity that really stuns the ear. It's so obvious to hear the skirt noise drop away and the voice in the middle of the passband jump in clarity. Flick the switch to cut out the cascade, and the radio returns to the full-sounding audio for casual rag-chewing... You have transformed the FT-920 into a super premium receiver..."

Click here to see performance curves of the Switchboard with 2.1 kHz and 1.8 kHz SSB filters.

*Yaesu FT-1000MP & Mark V Front End Mod
We now have a mod for the FT-1000MP: a small 70MHz I.F. amplifier. It boosts the front-end gain a few dB. The IF gain setting in menu item 9-1 is then reduced to compensate, and the radio's background hiss is greatly reduced. The byproduct is increased sensitivity of 2-4 DB in noise floor reduction. This is a plug-in, no-solder mod which can be easily removed. The Front End mod will also work in the MARK V, except it requires soldering two connections. This mod applies to the new Field model also.

Full installation instructions are available here:

  • Yaesu FT-1000MP/MarkV/Field IF Mod Installation Manual
  • See our Secure Order Form to order.


    *Yaesu FT-1000MP AGC Improvement Mod
    Some operators on major DX-peditions have complained about poor readability in large pile ups. From a joint effort between INRAD and some of these operators, we are now offering the AGC mod which improves readability somewhat for both CW and SSB. Details of the history is included in the mod instruction sheets. This new mod increases the decay time, which in the FT-1000MP is so fast that weaker signals can come up to full output between dots and dashes (or speech peaks), causing poor readability in pile ups. It also uses a damping resistor to eliminate a slight over shoot. Please be aware that under "normal" or "average" operating conditions, this mod will make very little discernable difference. The AGC mod is not applicable to the Mark V. See our Secure Order Form to order.


    *Yaesu FT-1000MP & Mark V Roofing Filter
    International Radio Corp is building more FT-1000MP (and MV and Field) roofing filter mods. These roofing filters can substantially reduce the third order Intermodulation from multiple strong signals in the 2 to 20 kHz region either side of the tuned frequency. Please see our PDF document titled "A few words about Roofing Filters" for more details. This is a plug-in, no-solder mod that can be easily removed. The roofing filter will also work in the MARK V, except it requires soldering two connections. This mod applies to the new Field model also. NOTE: This unit cannot be installed along with our 70 MHz IF Mod. Only one or the other can be used.

    Full installation instructions are available here:
  • Yaesu FT-1000MP/MarkV/Field Roofing Filter Installation Manual


  • For background information about roofing filters, plus performance data and customer comments about the new INRAD Roofing Filter for the Yaesu FT-1000MP series, as well as our plans for Roofing Filters for Ten-Tec and ICOM radios, click below:

    - roofing-filters.pdf

  • Click here to see the February QST review.
        Reproduced with the kind permission of the publisher, the American Radio Relay League.
  • Click here to see the January RadCom review.
        Reproduced with the kind permission of the Radio Society of Great Britain; copyright RadCom.


  • See our Secure Order Form to order.


    *Yaesu FT-1000 & FT-1000D Roofing Filter
    International Radio Corp now can supply a roofing filter mod for the FT-1000 and FT-1000D. These roofing filters can substantially reduce the third order Intermodulation from multiple strong signals in the 2 to 20 kHz region either side of the tuned frequency. Please see our PDF document titled "A few words about Roofing Filters" for more details.

    Installation is simple and requires soldering the +12V and ground wires. One coax is moved and a coax jumper is added. Full installation instructions are available here:
  • Yaesu FT-1000/FT-1000D Roofing Filter Installation Manual


  • See our Secure Order Form to order.

    *Yaesu FT-1000MP / Mark V / Mark V Field Keying Improvement
    The MP keying rise time is 2.4 mS and fall time is 1.0 mS. The fall time is responsible for the somewhat wide signal, which the MP generates on CW. There are two points in the radio which can be used to improve the keying by slowing the voltage change over from receive to transmit and back.

    Three parts are added to the radio. Two go on the IF board and one goes on the RF board. They are small leaded parts which solder on the bottom side of the boards. Board drawings are supplied which show the part locations. The IF board is fairly easy to get at. The RF board is buried under the final amplifier and is somewhat difficult to get at. Estimated time to install is 1 hour.

    For actual spectral data on the keying improvement made by this mod, click below:

    - about-key-clicks.pdf

    See our Secure Order Form to order.


    *Yaesu FT-101 WARC Band Modification Kit
    FT-101-Mark through FT-101F. (Not for FT-101ZD)

    FT-101 - Price reduced to just $45.00!

    *Fox Tango Tone Pulser Kit
    "One of the best gadgets for Fox Tango ever produced," writes a long time F/T participant. A small (1.5" square) PC board, easily mounted in the base of a desk mike or little plastic box, produces pulses of audio 2 kHz tone at a rate to simulate load factor of audio speech (30%). Thus when injected into the mike or patch input jack, a constant signal is produced which, in the SSB mode, can be used to tune the final amplifier(s) at a maximum power without concern for damage to final amplifier tubes regardless of how long it takes. Operates on its own 9V battery (not included) or power from rig. THIS KIT IS NO LONGER AVAILABLE -- BUT A NEW AND MUCH IMPROVED MODEL IS IN DEVELOPMENT AT THIS TIME. CHECK WITH US LATER THIS AUTUMN!.


    ICOM

    *ICOM IC-756PROII Roofing Filter
    International Radio Corp is taking orders for a roofing filter mod for the IC-756PROII. This roofing filter can help reduce the third order Intermodulation from multiple strong signals in the 2 to 20 kHz region either side of the tuned frequency. Please see our PDF document titled "A few words about Roofing Filters" for more details.

    This mod is significantly more challenging to perform than our other roofing filter kits and requires removal of some SMT components, cutting of board traces, and modifying a shield, and putting small connectors on teflon RG-178 coaxial cables. It should only be performed by those with considerable technical skills who are comfortable working around delicate electronics and small surface mount components. Note: this mod is applicable to the Pro2 only.

    *ICOM IC-765 and IC-775 Roofing Filter
    International Radio Corp now can supply a roofing filter mod for the IC-765 and IC-775. These roofing filters can help reduce the third order Intermodulation from multiple strong signals in the 2 to 20 kHz region either side of the tuned frequency. Please see our PDF document titled "A few words about Roofing Filters" for more details. Installation is simple and requires soldering T8V, R8Vand ground wires. One coax is moved and a coax jumper is added. Full installation instructions are available here:
  • ICOM IC-765 Roofing Filter Installation Manual
  • ICOM IC-775 Roofing Filter Installation Manual



  • See our New Web Site to order.

    *ICOM IC-765 Full QSK Keying Improvement Mod!
    Easily done -- notable improvement! See Order Form to order.


    TEN-TEC

    *Ten-Tec Omni VI Receive Audio Mod
    The Omni VI is a great CW radio. Here is a mod which greatly improves the SSB receive audio. Both the upper cutoff and lower cutoff are extended and the in band ripple is eliminated with this mod. The result is crisp, clean sounding receive audio. Installation can be done in 30 minutes. See Order Form to order.

    *Ten-Tec Omni VI Roofing Filter Mod
    Roofing filter mod boards and filters can now be ordered for the Omni series radios. Installation in the Omni VI and VI+ is very easy and requires soldering +12 and ground as well as extending a 2 wire cable by 5 inches. ( This unit will also work in the Omni V, but the customer must splice two coax cables due to the different pc board connectors.) All parts and instructions are supplied. Full installation instructions are available here:
    Omni Roofing Filter Installation Manual

    The pc board is mounted on two standoffs which fasten to the final amplifier shield can. Two coax cables insert the roofing filter between the RF board and the 9 MHz IF board. A two screw terminal board connects to +12 and ground. The N1/N2 switching cable gets extended and plugged into the Inrad board. A supplied jumper cable connects back to the IF board. A four position DIP switch is used to set up the roofing filter function. It may be selected with either N1 or N2, or both. The actual OEM filter positions N1 and N2 may be populated or not.

    The table below shows the measured third order IMD dynamic range of the OMNI VI+ for its unmodified (OEM) condition, modified with the 600 Hz filter and modified with the 2400 Hz filter. The improvement is quite dramatic and places the Omni VI into the group of today’s top performing radios.

    Tone Spacing OEM 600 Hz filter
    2400Hz filter
    2 kHz 79 dB 94 dB 85.5 dB
    5 kHz 82.5 97 95.5
    10 kHz 86.5 98 96.5
    20 kHz 95 97.5 97.5

    You may order the Roofing Filter mod for CW or SSB.

    The filters are 4 poles. Only one filter will fit on the board; you choose, depending upon how you will use the mod.



    The available filters are:
    • #764 – for SSB -- 2400 Hz.

    • #763 -- CW normal pitch – 750 Hz pitch. (Use with N1 or N2 filters centered on 9000.75.) This is the usual CW choice.

    • #765 – CW low pitch – (Use with N1 or N2 filters centered on 9000.5 or 9000.6.)


    See Order Form to order the Roofing Filter mod and the Filters.


    KENWOOD

    *Kenwood TS-930 Roofing Filter
    International Radio Corp is taking orders for a roofing filter mod for the TS-930. These roofing filters can help reduce the third order Intermodulation from multiple strong signals in the 2 to 20 kHz region either side of the tuned frequency. Please see our PDF document titled "A few words about Roofing Filters" for more details.

    Installation is simple and requires soldering B+, and ground wires. One coax is moved and a coax jumper is added.
    See our Secure Order Form to order.

    *Kenwood TS-950 Roofing Filter
    International Radio Corp is taking orders for a roofing filter mod for the TS-950S/SD/SDX. These roofing filters can help reduce the third order Intermodulation from multiple strong signals in the 2 to 20 kHz region either side of the tuned frequency. Please see our PDF document titled "A few words about Roofing Filters" for more details.

    Installation is simple and requires soldering B+, and ground wires. One coax is moved and another is added. Full installation instructions are available here:


    See our Secure Order Form to order.


    Home | About Us | Contact Us | Order | Announcements | Web Specials
    Filters | Crystals | Filters for Experimenters
    Performance Enhancement Kits | Publications | Turn Frames On

    ©1997-99 International Radio, Aptos, CA. All Rights Reserved.
    Web site designed by Scott Neader, KA9FOX of Internet Solutions
    Web site hosted by QTH.com