6400 Receive Antennas

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Another new 6400 user dumb question:  When I bought this radio it claimed to have "2 independent receivers."  So I create 2 panadapters, and create a slice in each.  On the top one I put the band on 20 meters, and on the bottom one I put it on 6 meters.  I have my 20 meter connected to antenna 1, and my 6 meter connected to antenna 2.  But regardless of what I do, when I set the 6 meter slice to antenna 2 it also changes the 20 meter slice to antenna 2, and vice versa.  Is this a defect, or operator error, or did I buy the wrong radio?

Brad K9BM
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k9bm .

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Posted 1 year ago

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Mike - VE3CKO, Elmer

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The 6400 has one SCU, spectral capture unit, and the the 6400/6700 have two SCU's. You can open up multiple panadapters on the 6400 but they would all be using the same antenna since there is only one SCU.
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k9bm .

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So how does this, by anyone's common sense definition, constitute "2 independent receivers?"
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Mike - VE3CKO, Elmer

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Your 6400 is working as designed. To achieve what you are trying to do, which is one panadapter on 20m ANT1, and 6m ANT2, you cannot do that on a 6400. However you can with a 6400 or 6700.
(Edited)
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k9bm .

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OK, I guess I'm too stupid to own a Flex.  It's FOR SALE, for anyone reading this, 3 months old in factory carton, automatic antenna tuner and hand microphone, $2,000 shipped in CONUS.  I'm ordering an Icom 7610, it's $1,000 cheaper than a Flex 6600 and actually DOES have 2 "independent receivers" as far as I can determine.  Please post if interested....
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Mike - VE3CKO, Elmer

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I remember when I was looking to upgrade from the 5000A  was contemplating 6300, 6500 and 6700. At the time I choose the 6500 and doing the research knew that it had only one SCU was disappointed I could not receive from two different antennas at the same time but I knew what I was getting into.  I was very happy with it, but eventually upgraded to the 6700. 
I suggest before you make a rash decision do your research, see what others are saying about the 7610. SmartSDR and the 6xxx series has so many advantages and you may come to the conclusion as many are, the 6600 is well worth the difference.
(Edited)
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Alan W4FBI

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I think Mike meant 6600 or 6700
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Mike - VE3CKO, Elmer

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opps, yes 6600/6700 typo, sorry Brad
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k9bm .

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Jim you are obviously correct.  My point is that Flex markets the 6400 as having "2 independent receivers."  What exactly is independent when you have to use the same antenna?  How many folks have a log periodic that covers from 20-6 meters?  I don't see anything "independent" about the alleged 2 receivers in this radios, it simply has split receive off the same antenna which mid-level dial radios have had for the last 40 years.  Shame on me for not asking more questions before buying....

Again, the radio is for sale, under the factory warranty, you get the antenna tuner and shipping for the price of the radio alone.  I'm moving on to a radio that does in fact have 2 independent receivers....

73, Brad K9BM
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Ken - NM9P, Elmer

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Brad, One thing I did that allowed me to use HF dipoles and a 6 meter antenna at the same time on one antenna ports was to get a Comet CF-360 "duplexer" which splits one antenna into two ports - or combines two antennas into One port.  One for 1.8-30 MHz,  and the other for 49-470 MHz.  I was able to use the antenna on two ports.  

You might find that as a simple way to split your LP to allow using HF on ANT1 and 6 Meters on ANT2)  giving you what you want.

I haven't done it this way, because I was combining two antennas into one port, but it should work.

Ken - NM9P
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k9bm .

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Ken, that's a really good idea and I would jump on it if I wanted to sell my 160-6 meter solid state amp.  But after scratching my head half the afternoon I just can't up with a way to configure a 6 meter antenna and an HF Yagi to use with the Flex 6400.  All I want to do is monitor 6 while working HF, and I seriously feel someone at Flex should review the dictionary definition of "independent" and then revise their marketing of the 6400. 

An "independent" receiver does not require the use of the same antenna as another receiver, it means 2 separate radios in the same box.  We can talk esoterica all afternoon about spectral capture units and slices, but unless you're a well experienced SDR user or experimenter you will interpret the marketing claim of "2 independent receivers" exactly the same way I did....
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WQ2H - Jim Poulette

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Brad,

Just to confirm - I don't have experience with the 6400, but the FDX mode and SO2R operation do function correctly on the 6600M. Technically the 6400 does have "two receivers", but does not have two "independent SCUs". As Mike suggests, I think that's the issue. 

Not exactly sure what you're trying to do, but you may want to double check if the Icom actually allows you to monitor a channel while transmitting on the other. It advertises "two receivers" just like the 6400 - but there is very little other information that I can find. If you really want SO2R capability an option could be to upgrade to the 6600 (4 independent receivers and 2 SCUs). The learning curve is a little longer, but I'm finding it well worth the extra effort.

For me it was an SDR toss-up between the Yaesu, Icom, or Flex. In the end I was just more comfortable with the Flex, even though the learning curve is a little longer.

In any event, good luck!

73 Jim, WQ2H

(Edited)
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Clay N9IO

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Brad,
The 6400 is most similar to the 6300, 1 scu, 2 slices (receivers.)
I started with the 6300 and honestly use my 6600 the same as I did the 6300.
Similar to the Antenna Genius I use a SixPak . I set it up to receive on antenna 1 side of the switch and Transmit on the B side.but I am on the same band beit DXing or ragchwing. Two separate bands with two separate antennas is achieved with the 6600 and 6700 models.
No disrespect but sounds like you're about to make another under researched decision.
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Craig - KØCF

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Be aware that the Icom IC-7610 can NOT use two antennas for the two receivers. It has only 1 ADC and works in the same way that the 6300 and 6400 do. Download the manual and take a look at it. If you want full duplex receive, you will have to get a 6600 or a 6700, both of which have two SCUs.
Or the Icom IC-7851, which is a LOT more money than even a 6700!

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Doug Hall

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Craig,
The IC-7610 Advanced Manual page 78 shows two ADCs with the ability to select a different antenna for each receiver. Is this incorrect?
73,
Doug K4DSP
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Craig - KØCF

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Doug, I stand corrected. The review that I saw was wrong. However, the manuals are very brief and vague about dual receive operation. Others have suggested that it does not do full duplex. I would suspect that both receivers are muted when transmitting, which would mean that it would not work in an SO2R contesting situation. But as far as I could find, Icom doesn't say one way or the other.

p.s. I owned an IC-7600 for five years and loved it. But my 6500 is better.
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k9bm .

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Thanks Craig, I did check and it appears you are correct.  This is all WAY too much for what I'm looking to do.  I think I'm better off just forgetting about 6 meters until I get a ping from a spotting reflector, or just use my old Icom 756PRO hooked up to NiMM which is perfectly capable of handling SO2R.  In fact, I could buy 2 or 3 dial radios that can be computer interfaced before I would reach the cost of an SDR radio with 2 SCUs and true "independent receivers."  I appreciate your help....
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Greg - N8GD

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I've never done so, but why can't you use the receive only input (RXA IN) or the transverter input (XVTR-A) for your 6M monitoring?  You'd have to switch to the active transmit slice and change to the 6M band to transmit, though.  The RXA IN port is receive only and goes directly into the same spectral capture unit (SCA) that your ANT 1 (slice A?) is connected to, but with no transmit capability.  It will permit that receive only capability on a separate antenna, however.
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mikeatthebeach .

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You can use a 20meter thru 6meter Hex Beam on that Flex6400
73 Mike

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Rick WN2C

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I haven't seen where Flex claimed to have 2 independent receivers on the 6400. From the Flex website is the following for the 6400...

With a PC, laptop, or Mac client you can utilize up to two 7 MHz spectrum/waterfall displays and independent receivers to revolutionize your view of the bands. Its two receivers can be placed simultaneously on any band and mode with instant QSY between VFOs. Digital mode operation is a dream with no sound cards, cables or boxes needed.

What it is actually saying is that you can have 2 slices open on any band.
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Mike - VE3CKO, Elmer

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We are all responsible for our own station. Seasoned ham or new to the hobby, when we make mistakes are do not do proper research, if there is any blame we must just look in the mirror.

We bite the bullet and we learn from our mistakes.

(Edited)
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WQ2H - Jim Poulette

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I find this thread intriguing, and I didn't find the remark condescending in the slightest. Although, frankly, the innuendo of misrepresentation clearly could be.

Unfortunately, as a career engineer, I deal with similar scenarios almost every day.

The definition of 'receiver" is fairly clear. Maybe even widely accepted and defined. Throw in the word "independent" - OK, that's clearly a little marketing. What is not clear is any further performance interpolation from a potential customer. If I can speak freely, that sounds more like wishful thinking or, poor planning.

73 Jim, WQ2H

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Let me ask you this:  If I sold you a pair of Drake 2C receivers with physically welded together cases and the antenna input ports physically welded together with hardline to a single input and I called them "2 independent receivers," would you consider that a fair marketing representation?  Now what if I sold you the same two receivers truly separated, packed in separate boxes.  Would you now believe you had received "2 independent receivers?"

As pointed out, both "receiver" and "independent" are well understood common language words, and I feel it's at the very least disingenuous of Flex to stand on some arcane usage technicality of SDR engineering design.  Was I misled?  You bet I was.  Should I have done more homework?  Obviously....

Brad K9BM
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k3Tim

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CK722 - Germanium - the good old days....
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HCampbell WB4IVF

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Brad, before you order the 7610, you might want to peruse the user manual.  ICOM makes fine radios (I have 3), but like any radio, it has shortcomings, and you might find that it lacks other features that may be important to you.  That’s why I opted for a Flex instead of the ICOM.   

BTW, my first “radio” was a brand new Hallicrafters S-120, followed by a Heathkit HW-16 rig, so I guess that qualifies me an “expert” in old age too!  (-:

Howard




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Ken - NM9P, Elmer

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Gentlemen...please let's dial back the pejorative a bit.  It isn't necessary.

I have been a ham for 44 years, and I was tripped up by this at first.  I ordered my 6500 in January 2013 before any of them were released, after having drooled over the 6700 for a while, but unable to afford it.  (I hope I didn't make the poor 6700 rust out in the process...)

After having read the many of the descriptions of both rigs, and trying to assimilate the technical information, and waiting on pins and needles until August 2013, I received my 6500 and put it into action.

I remember being thrilled, even with the initial pre-release software (some 4 or 5 releases before V.1.0.0 was released to the masses).

But I remember being surprised that I could not receive on both antennas at the same time (HF and 6 Meters)  What I discovered was that I had build my assumptions based upon descriptions of the 6700 and applied them to the 6500 (the only other option at the time, and announced a little bit after the 6700 was announced).

Once Tim explained to me (for the second or third time) the difference between having 2 or 4 slices and the advantage (and expense) of having 2 SCU's, I was satisfied, even if a bit frustrated..

Why the confusion?  

In the final analysis, especially at the time the 6000 series was released, there simply was no frame of reference that easily and adequately explain the new technology and terminology.

The Direct Sampling rig was a whole new ball game?

Multiple VFO's?  Well not exactly....We have 2 or 4 or 8 Slices....but they can tune different bands at the same time....So they act sort of like multiple VFO's but they are much more than that.  They are more like independent receivers all operating off of the same antenna (SCU).

Oh...and you can put different slices on different panadapters and watch them separately....

Multiple receivers?  Well...different slices are LIKE different receivers...but not quite....(see above) If I have an antenna with wide enough coverage, or can combine two antennas into the same RX port with a combiner or duplexer, I can listen to multiple bands from 160 - 6 meters at the same time.  But they all use the same antenna port.  (either ANT1, ANT2, RXA, XVTR, etc.)

We can have one or two SCU's, depending upon the model....Are THEY Different receivers?  Well sort of...If you have 2 SCU's you can use two different antennas at the same time..... 

Do I need two SCU's to do full Duplex?  No...You can do full duplex with only one SCU, but you need to use a different Receive antenna and port than you are using for your transmit antenna.  And you need to have enough port-to-port isolation and filtering so that your transmit signal does not overload your receive port.

Does having 2 SCU's guarantee the ability to do Full Duplex?  Not necessarily, because some manufacturers may not have enough isolation and/or filtering to do full duplex - On the Flex...yes, within the proper parameters....

Full Duplex and 2 SCU's are not one and the same.

The new technology of Direct Sampling SDR's has turned the whole lexicon on its side - introducing a whole new vocabulary, but also incorporating some of the old words, but with new meanings.

It can be very confusing to those making the shift from traditional radios and terminology to understand the new way of doing radio.

And, alas, it can be difficult for fans and marketing to translate the new terminology into language that new buyers will understand without making errors of assumption.

I am certain that FlexRadio is not deliberately misleading people with their ads.  Frankly they don't need the grief that would create.  (By the way, they have a 30 Day return policy if a customer feels they made the wrong purchase.)

But at the same time, no one needs to have their intelligence or operating ability or skills questioned because they may not have fully understood, or have made assumptions about the complex technology involved with the 6000 series.

These are wonderful, but complex pieces of high tech equipment that are redefining the amateur radio lexicon. 

Those of us who have been in the "deep end" of the pool for a long time can sometimes forget what it was like the first time we jumped in to test the waters.

Lets give each other a little grace...and patience.

Ken - NM9P
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Greg - N8GD

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As usual, Ken arrives as the voice of reason.  That, along with his technical knowledge, excellent writing skills, and ability to make a complex subject easier to understand, makes him more than worthy of the title "Elmer."
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Bill Roberts

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As a ham of 54 years (read that "old man") and Flex owner since 2010 (Flex 5000 to 6300 to 6600 in 2018), I experienced no difficulty understanding the difference between 1 and 2 SCU radios or the front end/filtering differences between all models.  Now, I'm all for extending grace but I take minor exception to folks accusing Flex Radio with misrepresenting their products.  The product comparison table states that the 6300 and 6500 radios are single SCU and incapable of full duplex or diversity reception.  The 6600 and 6700 are capable on both counts.  More importantly, if a person is unhappy with his/her purchase decision, they DO have 30 days to return or upgrade the product.  Do I-K-Y do that?  When I consider how patient and kind Flex guys were to newbies like me, whether over the phone or at hamfests, I have difficulty hearing them accused of misrepresentation.
(Edited)
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Roger, W6VZV

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It would be a real bummer to "move on to an Icom" and then find out that its "independent receivers" are the same as the 6400M.  For every transceiver I've ever owned, the "second independent receiver" was not really a stand-alone separate receiver -- it was only good for listening using the same antenna and usually on the same band.  My FT-1000MP MarkV, which was near-top of the line when I bought it (back when dinosaurs roamed the earth) was like that.

de Roger W6VZV
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Ted VE3TRQ

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To be fair to the 7610, it does have two ADCs, albeit I believe they are not quite equivalent to each other. The whole conversation about heat sinks on the 7610 ADCs clearly indicated two of them. And the 6400/6600 are also not free from heat sink issues. Both Flex and Icom make good radios, but none are perfect.
(Edited)
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Robert Lonn

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Roger,, still have my FT-1000MP MarkV,, 200 watts and 80 watts Class A operation... And a Synchronous Detector,, glad FLEX has one as well!!

Robert 6600M
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k9bm .

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Based on the length of this thread and the number of folks who have weighed in, I think it's fair to say this is NOT a black and white issue.  Ken NM9P had the most sober assessment of the different angles.  To be clear, I never said that Flex had hoodwinked me or misrepresented its product.  What I did say was that Flex used language that was misleading to anyone without an intimate knowledge of the architecture of SD radios.   And I stand by that position, feeling that Flex should share some of the burden of ushering in a new age of radio by helping folks, old and young, understand what they are buying.  If they attach new meanings to old words, this should be clearly explained.

Anyway, I've changed my mind and decided to keep the 6400.  It's not even remotely worth an extra $2k to add 6 meter receive capability.  I have my old Icom 756PRO collecting dust, so I'll interface it with the computer and monitor 6 meters while using the 6400 that way.  I am truly grateful for all the comments, and I guess I'm (slightly) smarter than I was yesterday....

73, Brad K9BM
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Ken - NM9P, Elmer

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Brad,  I think you will find, as I did with my 6500, that you have purchased an excellent rig.  Although there is a bit of a learning curve, once you master the panadapter, the settings for AGC-T, and Mic Profiles, you will be amazed at its performance, in spite of the initial letdown of expectations regarding the definition of the receiver(s).

I wouldn't be without my 6500, unless it was to upgrade to the 6600 some day in the not to distant future.

Good luck, and as I can be helpful, please contact me.

Ken - NM9P
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Roger, W6VZV

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OM I am a new 6400M owner/user and I have been totally loving the rig.  I am pretty sure that you will too.
de Roger W6VZV
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Lasse Moell

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If you just want to montor 50 MHz, why not get a SDR-receiver like the Elad S2, this will allow you to see whats going on, and if there is someting you can quickly switch over to the Flex.
The S2 covers 0-60 plus FM/Air and 2 meters and then some.
/Lasse SM5GLC
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Robert Lonn

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WOW, things are calming down now, and we have another loyal 6400 Flex Customer!!! Before I decided on my 6600M, I spent an hour on the phone with Flex marketing.. I had my list of questions, and they were all answered.. 8 out of 10 questions were answered with a Thumbs Up, I like that, but two questions did not satisfy my radio operating desires, but they were Far Down my list of must have in my radio needs and one of two might be in a future software release.  I also asked a lot about their manufacturing techniques in Texas, and their QC process etc. etc.  One thing I was VERY EXCITED to hear was that Flex charges $200 to upgrade to a new Higher version of Software!!! So when 3.0 is released, It should have some very exciting features.. And we know that development cost time and labor cost.. If Flex could not recoup some of their cost, then where is the incentive to spend the time in development?? If it all plays out, that $200 will get Flex Owners a Next generation Software Package... In the meantime 2.XXX will continue to get minor upgrades and changes For Free!! 

Thanks Flex
Robert 6600M
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Bill -VA3WTB

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Robert, I remember Gerald saying that the $200.00 does not even cover the cost of development. 
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Robert Lonn

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Your Correct,, So Flex charges a Modest Amount, they probably could charge $1000, but most people will probably Run Away, so $200 seems like a sweet Spot...