Question for Flex 6300 owners

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  • Updated 3 years ago
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  • (Edited)

FLEX SAYS: "The FLEX-6300, FLEX-6500 and FLEX-6700 all have the option of receiving from the
XVTR port. The XVTR port is not recommended as a receive antenna port if an external preamp is used on its antenna. Transmission on the XVTR port could put up to +10 dBm of reverse power into the connected preamp."

 Many people I know, including myself, use a variety of preamps as needed on their extensive receive antennas.  My Hi-Z array has 8 preamps with one at each 24ft tall rx antenna and I have another two available inside the shack as well as the DXE preamp at the array center (over 800ft away).  Isnt there a way to inhibit the TX side of that same bnc connector so up to +10dbm of power doesn't fry the preamps?   I know I am ok with the 6700 as I have dedicated RX inputs but what about the users of a 6300?   I sent my 6700 in for a tuneup so currently I cant open the GUI to check if indeed the Xvtr port can be inhibited from TX only. (and of course I cant remember) .

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K1UO - Larry

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Posted 6 years ago

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Photo of Steve - N5AC

Steve - N5AC, VP Engineering / CTO

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Official Response
First, during the PowerSDR era, placing an extra checkbox on a form to enable a feature for a set of users was less of a concern.  But we learned that the more of these kinds of things we add, the greater number of instantaneous modes the radio could be in and the higher likelihood that the operator will get confused about the "mode" of the radio and have difficulty operating it.  Our GUI designer now jokes that every time we request a checkbox option "an angel loses it's wings."  It's a tongue-on-cheek expression, but the point is valid: lots of options add lots of complexity.

Second, from our perspective, the more options like this that are added, the higher the support load becomes because operators can casually check a box like this and then totally forget the box ever existed.  Later when they are trying to transmit, we end up fielding a call from an upset customer that has spent several hours taking apart their station trying to find a problem, and believe their radio is broken.  Although the resolution might be quick, it's no fun for our customer to have this kind of experience.  This can also be embarrassing for a customer when in reality it's our fault for making something complex, really.

Third, I am a microwave guy and so my entire lash-up consists of a cascade of amplifiers, preamps, power supplies, etc. all depending on one another.  Most microwaves will tell you that if you build a hardware system than can blow up if it weren't for a software setting, that what you have is a ticking time bomb.  In other words, if you can break something with a setting in software, you eventually will.  Knowing that your system can never achieve an over-power, over-current, over-voltage, etc. condition if you do something wrong in the operation of the station brings a certain comfort.  It's nice to be able to tell a fellow ham "sure, try it out -- you're not going to hurt anything."  I've operated stations before where I've been given very strict instructions that ended with "and if you do ___________ you will destroy _________ which will cost me _________."  It's a lot less fun to operate given that set of conditions.

Fourth, as I suggested before, I think it is likely that this level of RF wouldn't hurt most devices anyway.  In the HF world, we're all used to thinking that transmit power kills anything but antennas, amplifiers, coax and relays, but this is a very low level of power.  If it's not a problem let's not fix it.

For these reasons, I'm going to resist doing something like this.  But if it is shown that this is a necessary thing to do, of course we'll go do it.  I'm just asking that before we complicate things for everyone, let's make sure it has to be done.