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Author Topic: Maxx-com tuner revisited  (Read 4803 times)
WA4HND
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Posts: 42




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« Reply #15 on: February 04, 2004, 08:24:34 PM »

Lon,

Forgive me if I sound "east coast" here.... ( yep I was born in Philly.  But I could care less what you think. )

I have no reason to push this thing... all I'm saying is that it does do what they say and I have all the toys to compare it with.   I have two SGC QMS systems with 230 tuners, 303 whips and power cubes.... that's not a small amount of change.  

I also have some K0DU antennas and they are, in my opinion, one of the best mobile antennas you can have.  If I want to put out a big signal and work DX... that's the setup to have.  

All I'm saying is that these maxx-coms do work ( which I admit surprised the heck out of me <g> ).  They will get a decent signal out nomatter what. Yes you can do better with a tuned antenna...but if you dont' have a tuned ant for the the freq you want to use... or your tuner stops working for some reason.... or the screwdriver doesn't screw....  a maxx-com will get you on the air.

Sounds to me like you're just sorry you're not selling them < G >.

If you want to call it snake oil and all that... that's fine with me.  (that is if you have tried it yourself)  .... but if that's not the case, I'd suggest you qrt from the conversation.

Al
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KC2MMI
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Posts: 623




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« Reply #16 on: February 05, 2004, 01:27:21 AM »

Bob-
 <by hiding disconnected junk in the device that would show up on xray examination.> That's *not* unusual behavior for a company selling potted units that they feel are a trade secret. I've been told by several people that they would routinely put "stuff" in an epoxy potted item so that anyone trying to copy it would be thrown off or slowed down, so I wouldn't hold this against Maxx-com.

 OTOH, pretending there even CAN be secret smoke inside an antenna "coupler" going to a technical audience is, well, let's say not the kind of marketing approach I'd try.<G>

 It sounds like a transformer with some diodes and resistors to eat the reflected signal. Probably could be unraveled in any college physical science lab in one long day, consuming two or three units as they were ground/etched apart. Of course, companies that want to protect trade secrets also usually grind/etch all markings off the components they use...but I suspect that would only make it take a couple of days longer to figure out the exact values, once the basic circuit was diagrammed.

 Anybody know some undergrads with time on their hand and money to waste?<G>
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WA4HND
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Posts: 42




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« Reply #17 on: February 05, 2004, 01:45:12 AM »

I would think it would be fairly simple to figure out the circuit given the right equipment...  but like I said in another post, copying the circuit is not on the top of my to-do list.  What was on the top was to see if the thing worked at all and now I know the answer.

I would think maybe that all the "snake oil" people around here should pitch in together... buy a unit and try it out!  

Then _they_ could see how it feels when they come back here and admit that they work! <g>.

Al
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K0BG
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« Reply #18 on: February 05, 2004, 11:03:36 AM »

In one of my articles published here on e-ham.net, I made a suggestion about placing a dummy load out in your back yard, and connecting an 8 foot wire to the center conductor of the feed coax using a "T" connector. At least 5 folks did that and reported back to me. One of them reported working a JA on 20 meter CW and being told he was 40 over S 9 in Tokyo. With 100 watts in, the effective radiated power is in the order of .5 watts, or QRPp. As an EE you should be able to figure out the dynamics. Hopefull.

Alan, KØBG
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WA4HND
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Posts: 42




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« Reply #19 on: February 05, 2004, 12:44:17 PM »

Alan,

I know there are two threads on this topic.... maybe you guys missed something here...but point one... ( check tower talk also )  

In case you missed it,  I found that this is NOT a resistive load about 15 seconds after I opened the box <g>.  .... also the swr goes up if you have too short a feed line between the rig and tuner... it also goes up if you have no load on the outputs.  Obviously some inductive transfer going on here.

If this was just a "can" dummy load... this would not be the case with either test.  

If you didn't read this... then you're working with not enough info..... if you did read what I said already and still wrote what you did... then you don't know much about electronics.... or just trying to give me a hard time.  Not sure which it is, but the bottom line is it's a waste of my time and yours.  ( Frankly, I'm concerned more about mine <g> ).

Al
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WA4HND
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Posts: 42




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« Reply #20 on: February 05, 2004, 01:32:56 PM »

Alan,

Ok, I just reread my last post to you and just want to say I'm sorry.  You most likely didn't know what I had found out already and was jumping to the same thoughts I had about the thing when I ordered it.  

Like I said before, I figured I would get it in, measure 50 ohms on the input and send the thing back.... worst case ,I'd be out some bucks for a few weeks.  That is NOT what I found.

According to the maxx-com ads, they say the thing transfers about 80 percent of the rf to your load.  Based on what I can tell by changing out ants and doing some quick on the air tests... I have no reason to doubt that.  I can do more exact testing this spring ( when the snow melts and the temp goes above 30 <g> )... but for now, the unit is working fine and I'm not going to send it back.    

I do a lot of driving between Grand Junction and Denver ( in fact I'll be on the road tomorrow...  maybe you can catch me on the air )  But anyway, I'm testing this thing in all kinds of bad weather and so far, so good.
I'm sure I'll be able to play with some different loads and fine tune it some, but for now, I'm not going to ask it to do more than it already has.

In any case, you were thinking exactly what I was thinking and I sure can't give you a hard time about that.

Al
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WB2WIK
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Posts: 20666




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« Reply #21 on: February 05, 2004, 01:35:36 PM »

BTW, anybody who wants to de-pot the Maxx-Comm only needs a galvanized steel bucket and a half gallon of dimethyl formamide.  The solution dissolves epoxy but leaves metal parts intact.

I don't feel like buying a Maxx-Comm to do this, but if anyone already has one and like to see precisely what's inside it, let me know and I can de-pot it...

WB2WIK/6
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WA4HND
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Posts: 42




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« Reply #22 on: February 05, 2004, 03:32:46 PM »

I thought I replied to this, but maybe not ( or it got lost ).

Ref the de-pot.  I'm not going to do it to mine.... but if anyone finds one at a ham fest.... go for it!  My bet is that you'll find coils but by the time you pull them out of the slime, you may not be able to tell the values.

One tip.... test the unit before dumping it in a bucket... you may want to save it to use < G >.

Al
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K0BG
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« Reply #23 on: February 05, 2004, 03:40:16 PM »

Al, you haven't left your e-mail address so I can't really take this off line, and I don't mean to be condesending or demeaning. However, what Steve WB2WIK, and I (and others) have been trying to tell you is, you've been duped!

Maxx-Com very well may have changed the innards to be something more than a simple resistor as was the case several years ago when they presented one to the ARRL for review in QST. But the fact remains, it is little more (if at all) than a 50 resistor mounted in a box with a few connectors and filled with epoxy.

If you have an MFJ 239B or similar device, you have the unit installed, I'm sure you could plot the input impedance easily and with a few calculations figure out exactly what's inside.

That said, there are several mobile (and base station antennas too) which are very popular, and people swear by them, but they're not much more than a dummy load on a stick. Ask a few users and they'll tell you about all of the DX they have worked. But field measure one of these, and you'd be real surprised to see how inefficient they really are. One of these is the ATAS series be Yaesu. On 40 meters, its efficiency is in the neighborhood of 1%. Most of the Hamstick and Outback models fit into this catagory too. And so does the Maxx-Com.

If you ever get into a pileup on any band with Steve or me, conditions being the equal, you'll lose every time. If you're satisfied with it, fine, but understand that most of us know just how poor a radiator it is.

Alan, KØBG
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WA4HND
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Posts: 42




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« Reply #24 on: February 05, 2004, 04:14:21 PM »

Alan,

I hate to post email addresses on forums like this because the spam bots will pick it up and I'll find myself with 100 e-mails wanting to sell me something to  enlarge my.... ( well you can figure that out. )

If you'd like my email address, I'm sure it's posted on the Colorado RACES  web page.  ( coloradoraces dot net ).  I think I also have an email address on qrz.com

In any case... you remind me of someone who you'd like to just shake by the sholders and yell LISTEN TO WHAT I AM SAYING.

You constantly keep telling me about being dupped... I'm telling you I expected that to be the case and when I tested it, I found that it worked.  UNLESS YOU HAVE ONE AND HAVE TESTED IT.... DO NOT BEGIN TO TELL ME WHAT I HAVE FOUND OUT FOR MYSELF!!!

If I want to get into a pileup and work DX... I'll use one of my other systems.... I'll put my K0DU ant up against ANYTHING you can put on a jeep.... Pedator, High S, Bugcatcher.... you name it.. I either have them or have tested them.  I also know the downside of these guys and wanted something that was absolutly solid and worked no mater what.  ( while knowing I was going to give up one to two S-units ).

When you're programming, you use the right tool for the job... this is just like that.  There are times when 80 percent of an optimum signal is better than zero.  I have had SGC's fail, I've seen screwdrivers freeze up in sub zero conditions.  It's nice to have one system on a mobile em vehicle that you know you will be able to transmit into under ALL conditions and without having to get out and change coils etc etc.

Man, I came up here to just let you guys know what I found and days later, I seem to be having to defend what I've seen with my own two eyes and ears.  Maybe you have the time for this....but I don't.

Heck, as far as you knew, it what just a resister box... so you have already based your opinion on false info.... how the heck do you expect anyone to believe you?

If you want to prove you are right and I'm not... do exactly the same thing I did.... get one, test it and see what you find.  They have a 10 day money back guarantee... .. put up your money and test it for yourself.... at least then you would be able to argue on common ground.   If you're not willing to do that, then you have no argument at all and you're just killing time.  ( I don't have that kind of time to kill ).

Al
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WA4HND
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Posts: 42




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« Reply #25 on: February 05, 2004, 05:09:11 PM »

Alan,

I just picked up something you said about a message ago...

>>
but understand that most of us know just how poor a radiator it is.
>>

Maybe THIS is where you are going wrong.... the way this thing works it's much more of what I would call a coupler than a "tuner".  This box does not radiate.... it's depending on you to hook a radiator to it and what you hook to it has a huge effect on how good you get out…. I’ve tried different whips and wires on the thing and you can defiantly improve efficiency with the right ones.

If you think of this box as a “transfer” device that will always present a decent match to your rig, then you’re more in line with what the thing does.  IE if you have a good radiator, more RF gets into the air. If you don’t, more will be lost.  The bottom line is no matter what kind of radiator you have, your rig will transmit and not shut down.

Does this make any more sense to you?

Al
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N3ZKP
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Posts: 2008




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« Reply #26 on: February 05, 2004, 05:21:23 PM »

I never said it didn't "work". As has been said before by me and many others, a 50 ohm resistor across the feedpoint will do the same thing and a WHOLE lot cheaper.

No matter what you call it, it's still snake oil. Smiley

I'm happy you are happy with the performance of the unit. I wouldn't waste the money.

On another subject you make much of needing to switch frequencies very quickly during emergencies. As a disaster services professional for 35+ years, I have never seen this need on HF. Switch frequencies, yes, but no situation that one minute would make a life or death difference.

Lon
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WA4HND
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Posts: 42




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« Reply #27 on: February 05, 2004, 05:44:02 PM »

>>I never said it didn't "work".

...hummmmmm

>>
As has been said before by me and many others, a 50 ohm resistor across the feedpoint will do the same thing and a WHOLE lot cheaper.
>>

That's where you're wrong.... I've tried it.... unless you have also, you have no room to talk.... this guy is __way__ better than a 50 ohm resister.


>>No matter what you call it, it's still snake oil. Smiley

For those of you that don't have one, have never tired one and have no clue what's in it... I guess you can call it anything you want. <g>

>>
I'm happy you are happy with the performance of the unit. I wouldn't waste the money.
>>

Again, if you haven't tried one, you have no facts to base your comments on.

>>
On another subject you make much of needing to switch frequencies very quickly during emergencies. As a disaster services professional for 35+ years, I have never seen this need on HF. Switch frequencies, yes, but no situation that one minute would make a life or death difference.
>>

Remember, this thing will also work on UHF / VHF... if my UHF / VHF rigs blow up, this ant can be used on those freqs with zero change ...just push a button on my 857 and I'm there!

As for the minute, it took less than that for the people on the 105th floor to hit gound zero.  Talk to them about the minute!

But if you're just talking HF... maybe you have never done any NVIS work... when doing NVIS it's important to first find the correct freq that will work to give you the coverage you need.. being able to switch from 40 to 60 to 75 instantly is a nice advantage.  You also don't need a lot of power to do NVIS correctly so the "transfer" percentage is not as important as when you're working DX in a pileup.

But I'm happy that you now say "I never said it didn't work".... I guess that's some progress <g>.

Al
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K0BG
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« Reply #28 on: February 05, 2004, 06:27:22 PM »

Al, if you please you can e-mail me first at k0bg@aol.com. Yours is not on the web page you mentioned (I already looked there).

Let me tell you a quick story. Yardly Beers (sk) who lived in Boulder, CO (and other places) once placed a 100 watts light bulb atop a 60 foot telephone pole. He worked WAS QRP and DXCC QRP using said light bulb as an antenna. It took him several years, but he did it. The actual output was calculated to be just a few milliwatts.

The bottom line here is efficiency. If radiating under 1 watt pleases you, go for it. I'm upwards of 80% on 20 meters in my mobile.

Alan, KØBG
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WA4HND
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Posts: 42




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« Reply #29 on: February 05, 2004, 06:41:46 PM »

Alan,

I'll email you sure....but first let me ask you something.... if you don't have one of these things... and you don't know what's in it?  Where do you get this  off the wall stuff about one mw out?  

Geeze, you don't even know what I'm putting in... how can you tell me what's comming out?    Let's just say for an argument that this thing was nothing more that a 1 to 1 balum ( I'm sure it's not, but let's say it was ) and I had a 75 meter dipole on the other end.... do you still think I would only have 1 mw out???  

You have no idea what you're talking about here..... you're just talking!!!

I'm glad I've got a trip tomorrow... I doubt I could take another day of this type of logic.


Also, please give the details on how you are measuring your 80 percent on 20... I need to hear this one!!!


Al
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