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RFX85 HD Generic Install Guide
RFX85HD Parts Layout
RFX85HD Schematic Diagram

There are now 2 RFX85 choices: the standard
RFX85 and the new RFX85HD high drive.

The RFX85 circuit includes driver stage, final amplifier stage and low pass filter. The RFX85 is your choice for 10 meter radio repairs and upgrades that require replacing the radio’s driver and final amplification stages. It replaces the final stage so it is ON all the time and cannot be bipassed.

The RFX85HD circuit includes only the final amplifier stage and low pass filter which makes for a quicker and easier installation in some units. The RFX85HD is your choice for 10 meter radio repairs and upgrades when the final transistor good and intact and if you want to have the 85 in or out of line (on/off).

Both RFX85 units feature the new fan-ready heatsink design and variable bias controls for better tuning on SSB radio installations.

    This is a complicated modification and should not be done by an amateur.
You should probably leave the installation and alignment to a proven technician.




Comply with part 15 of the FCC Rules. Operation is subject to the
condition that this device does not cause harmful interference. Further i
nformation can be found at the FCC website or the
ARRL website

Transmitting using this radio requires an Amateur Radio License. Licensing
 information can be obtained by visiting or In
Canada, visit or








...RFX-85HD module...


Single Fan Kit You install the fan yourself . 1x Fans, 1x grills and 4x screws provided. $11

Dual Fan Kit You install
the fans yourself . 2x Fans, 2x chrome grills and 8x screws provided.


Use this box to add the RFX-85HD to a radio you have in your shopping cart.

Fan Options

  RFX-85 HD Final. Perform a tune-up to radio to increase power, audio and performance and add a new final section consisting of a high powered Mosfet.
(AM carrier 15 watts and 70-90 watts peak power depending on radio.) 
A switch for on/off included.

If the radio is unable to use this kit you will be contacted.
My testing so far shows about a 2x gain. So it outputs 60-65W with a 30W radio and 75w output with a 38-40w radio.  It may take a lot of peak power input drive (maybe 50+W) to get the 100w  peak that Palomar was saying it can do.   I think most 40-45 watt radios will do well with these.

See Also:



Fan Ready Heatsink Design
The RFX85 heatsink supports mounting one or two 40mm fans directly to the ns for forced-air cooling.

Maximum Input: 30 watts PEP
Maximum Ouput: 80+ watts PEP
Final Stage: ERF7530 MOSFET (x1)
Low Pass Filter: 3 Stage
Spurious Emission Suppression: 45 db
Supply Voltage: 13.8 VDC
Power Consumption: 12 amps max
Dimensions: 2.0 x 3.25 x 1.625 (LxWxH)
Weight: 8.2 ounces


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