1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

Output modification for the HR2510

Discussion in 'CB Radio Modifications' started by AudioShockwav, Jul 9, 2011.

  1. AudioShockwav

    Expand Collapse
    Extraterrestrial Admin
    Staff Member

    Apr 6, 2005
    Likes Received:
    The idea of this modification is to replace the Final Power transistor, Using Motorola MRF455 -
    ( Thanks to KB3CBS for the Info)

    Please Note:
    This is A way to replace the 'hard to get' original MRF477, while it is possible to get a little higher output, unless you have a damaged MRF 477, it is a substantial amount of work for this "slightly higher output",- about 40-50W SSB.

    MRF477 and MRF455 is quite different!!!

    - MRF477 vs. MRF455 Pinout -
    These 'pinout' images illustrates the problem using the MRF455 transistor in replacement of the original MRF477,- You need to mount the MRF455 Transistor to the heat-sink and make connections to the pcb using tree short 'hookup' wires. See the illustration below.

    MRF455 Hookup wires and HR2510 Main-PCB connections

    HR2510 Heatsink with Final Transistor MRF455 Mounted

    The image shows the HR2510 Heatsink with the MRF455 and hookup wires mounted on it,- I de-assembled the Heatsink to be able to drill the screw-holes to be able to mount the MRF455 transistor,- See the drill-diagram below.

    - 2SC2086 vs. NTE-340 Pinout -

    This mod also require`s that you replace the Pre-driver Transistor Q134, NOTE! the NTE340 use a different pin-out, simply turn the transistor 180 degrees when putting it in place.
    Both transistors use the TO92 Case, But the NTE340 is named 'TO92 Giant' because it is a bit longer on the top.

    Comparative Transistor data
    Transistor Type Descriprion
    NTE340 Si-NPN RF-Power/Tr, 86V, 500mA PQ=0,6W
    2SC2086 Si-NPN RF-Power/Tr, 75V, 1A, PQ=0,45W(27Mhz)
    Output power mod for the Uniden HR2510 & HR2600

    Uniden's HR2510 & HR2600 10 Meter Amateur radio's are nice for single band operation.

    M.T. Stacey KC4HGH in Septembers issue of 73 Amateur Radio (1989) Published his findings on power modifications to the HR2510.

    The modifications that follow are based on his works with some additions:

    The factory has the HR2510 & HR2600 output power levels set for continuous duty. I.E. AM,FM & CW 10 Watts, SSB - 20/25 Watts.

    ************************* POWER MOD ***************************

    PROCEDURE HR2510 HR2600

    Relocate capacitors to C122,C116 C122,C116
    bottom of Board. (This
    is to allow spreading of
    the tuned/trap output

    Replace Pre-driver Tx
    (2SC2086D) w/ ECG-340 Q134 Q34
    (Note pinout change)
    2510/2600's w/ the
    2SC1973 device require
    no pinout change.

    Replace output Transistor
    Q133 the MRF477 w/ MRF455
    use short hookup vires as
    described above Q132 Q32

    Replace Bias current R158 R158
    limiting resistor from
    82 ohms to 68 ohms
    1/2 watt device.

    Pull bias jumper board
    out of the circuit. PB100 PB100
    Place a current meter between pins
    TP2 and TP4

    Adjust Final bias for
    80-85 MA, USB position.
    No Modulation.

    Fire radio up with
    power meter and 100W
    dummy load attached.
    Adjust ALC for Maximum. VR104 VR5
    1Khz tone is helpful.

    Mode to AM/FM
    Spread coils L121,L123 L14,L16
    for maximum.

    AM/FM power adjustment,
    20 Watts is easily obtained.
    I think 25/30 may be pushing
    it in this Mode. (Melt Down.)
    Adjust controls for your VR103,VR107 VR4,VR8
    desired levels.

    My experience in increased output levels are as follows:
    "SSB Mode."

    HR2510 = 32 Watts AVG (1Khz Tone) / 45.2 Watts PEP
    HR2600 = 37 Watts AVG (1Khz Tone) / 52.3 Watts PEP

    The above measurements are made with Bird 43 into a 50 ohm load.


    1320 Grand Ave.
    San Marcos CA. 92069

    Thanks to KB3CBS for the Info for this Mod

    Attached Files:

    mrgumby likes this.

  2. AudioShockwav

    Expand Collapse
    Extraterrestrial Admin
    Staff Member

    Apr 6, 2005
    Likes Received:
    Hook Up Diagram

    The Hook up Diagram for the above Mod

    Attached Files:

  3. TonyV225

    Expand Collapse
    W9WDX Amateur Radio Club Member

    Apr 18, 2005
    Likes Received:
    I often thought about doing this aswell its a cool mod.

Share This Page

Members Online Now

  1. skk1988,
  2. BJ radionut,
  3. sp5it,
  4. Misfit,
  5. Yamridar,
  6. guayacan074,
  7. Kevin Veator,
  8. dave457,
  9. n8fgb,
  10. Tech299,
  11. Doodle bop,
  12. The DB,
  13. Robb
Total: 378 (members: 16, guests: 221, robots: 141)