FLEX-6400(M) & FLEX-6600(M) PEN Update

//FLEX-6400(M) & FLEX-6600(M) PEN Update
FLEX-6400(M) & FLEX-6600(M) PEN Update2018-05-25T21:35:18+00:00

FlexRadio has a continuous improvement plan in place for the FLEX-6000 Signature Series products. This PEN (product enhancement notification) outlines hardware performance improvements that apply to all FLEX-6400/FLEX-6400M/FLEX-6600/FLEX-6600M radios shipped new or from the service department prior to April 12, 2018All units serviced or shipped from FlexRadio Systems on or after April 12, 2018, already incorporate these upgrades.

Recommended Upgrade: Improve ADC Thermal Dissipation


The A/D converters used in the FLEX-6400/FLEX-6400M/FLEX-6600/FLEX-6600M radios are mounted on plug-in PC boards and incorporate a chip top copper heat sink. The heatsink is affixed to the top of the A/D converter with an adhesive thermal tape supplied by the component manufacturer. Recently it was discovered by our alpha test group members who leave their radios on 24/7 that the heatsinks were coming loose after a few months of continuous operation. While the A/D chip itself will not be harmed by the lack of a heat sink, the dynamic range performance can degrade or in extreme cases result in a high noise floor. In some cases, the heatsink has become completely detached from the A/D converter and fallen inside the radio.


The solution is to replace the original heatsink with a larger one with a higher rated thermal adhesive that is mounted to the bottom of the A/D converter circuit board. Since the A/D is on a small plug-in circuit board, the new heatsink is relatively easy to field install by anyone with reasonable hand assembly skills. FlexRadio will offer the option to provide the heatsink upgrade kit for field installation or the radio may be returned to FlexRadio to install the upgraded heatsink.

Optional Upgrade: RF Preamp RMDR Enhancement


This upgrade increases reciprocal mixing dynamic range (RMDR) when using the preamplifier on the FLEX-6400/FLEX-6400(M)/FLEX-6600/FLEX-6600(M) radios. RMDR with the preamp off (0 dB or -8 dB) is not affected by this modification. RMDR at 5 kHz with the preamp off has been measured at greater than 115 dB. The modification improves 5 kHz RMDR with the preamp turned on from greater than 105 dB to at least 115 dB.

Unless you frequently operate within less than 10 kHz of a 60dB over S9 station on the same band, this modification will have no effect. Typically, this will only improve operation for an M/1, M/2, M/M or SO2R contesting operation or other operations in high RF environments.


The circuit modification performed by the FlexRadio Service department adds two noise reduction capacitors on the LDO voltage regulator powering the preamp to reduce close in amplitude (AM) noise.

What is Necessary to Get My Radio updated?

All customers whose radio shipped directly from FlexRadio prior to April 12, 2018, will be contacted by email survey to determine if you wish to receive the recommended A/D Heatsink Installation Kit by mail or optionally if you prefer to schedule an RMA for our service department to install the upgrades.  PEN upgrades are scheduled to begin in early June 2018.

There are three options available for getting the PEN changes applied to your radio.

  • Option 1 -Field install the A/D Heatsink Installation Kit and forego the optional RF Preamp RMDR Enhancement.
  • Option 2- Field install the A/D Heatsink Installation Kit and then send your radio in at a later date for the RF Preamp RMDR Enhancement.
  • Option 3 -Send the radio in for both the A/D Heatsink Installation Kit and the RF Preamp RMDR Enhancement.

If you choose Option 1, the field installed heat sink installation option we will ship the free A/D Heatsink Installation Kit within one week of your request. This is by far the fastest way to complete the recommended upgrade on your radio.

If you prefer to return the radio to our US service department for Option 2, just the RF Preamp RMDR Enhancement or Option 3, both the upgrades, it will be necessary to receive an RMA (return merchandise authorization) and schedule the service time window.

Given a large number of radios shipped and the limited number of service personnel at FlexRadio you will be provided a date when your radio can be shipped in for service.  By waiting until this date to ship your radio for service, it will ensure that you receive your radio back as soon as possible.

FlexRadio will cover UPS Ground shipping both directions and will install the upgrades at no cost.  If you desire faster shipping, you may choose to pay the difference in cost to the upgraded shipping method. Please allow 5 to 7 working days in our Service department to complete the upgrades from the time the radio arrives in our office.  The radio must be shipped properly in its original shipping carton and foam packing materials to prevent damage in transit.

A dedicated email address has been set up to assist with technical queries concerning this enhancement notice: PEN@flexradio.com. The email will allow us to keep all questions and requests about your radio together.

Request a FLEX-6400/FLEX-6600 PEN

Please fill out the FLEX-6400/FLEX-6600 PEN Request form below to request one of the three installation options.
FLEX-6400/6600 PEN Submission Form
* Required Entry
Customer Information
PEN Install Options:
  • Option 1 - I wish to self install just the thermal enhancement kit, please mail me the kit.
  • Option 2 -Please ship me the thermal kit for self install and put me in the que for the optional performance enhancement.
  • Option 3 - I wish to send my radio in for both the thermal and performance enhancement. Please contact me for scheduling.