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Balanced line > Drake MN-2000 tuna ( condensed version )




 
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Author Topic: Balanced line > Drake MN-2000 tuna ( condensed version )  (Read 7304 times)
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KC2YOI
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« on: July 13, 2010, 01:43:18 PM »

I would like to put a Drake MN-2000 to work here. It would eliminate an ext. SWR bridge, several jumpers and switches. It will also better handle the L-4B

I'm running the 65' , 600ohm ladder & dipole. I would like to place two J. Mtchbx type posts, not just the S) 239's.

Is this possible or practicle? I want to avoid a balun at the tuner end.
 (as offered on the later Drake 7 series tuner for example).
            
Thanks for any help,   DJ                                                                                                                                                          
                
         http://www.radiomuseum.org/r/drake_mn_2000mn200.html
                                          
                                     ( example pics )

                                          
         http://www.radioamateur.eu/schemi/acc_matching/Drake_MN-2000_user.pdf
                        
                    ( Schematic, Page 11, rotate for ease of viewing  )
                          
                                        
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ka3zlr
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« Reply #1 on: July 13, 2010, 01:53:58 PM »

There's a thread on the forum on a Balanced tuner I built that thing there's nothen that'll touch it Smiley
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KC2YOI
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« Reply #2 on: July 13, 2010, 02:00:08 PM »

There's a thread on the forum on a Balanced tuner I built that thing there's nothen that'll touch it Smiley

I'll look for it. What search term would bring it up here?

                                              Thanks  
                
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DMOD
AC0OB - A Place where Thermionic Emitters Rule!
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« Reply #3 on: July 13, 2010, 11:02:11 PM »

Quote
Can I run a 600 ohm balanced line through a Drake MN-2000 tuner with out using a balun?

I have a Drake MN-2000 Pi-Tuner and while built like a tank, it does not have any privisions for modification, nor does it have any internal TLT's.

The best you can do I think is use one of these with a RG-213 http://www.universal-radio.com/catalog/cable/2929.html

out to it:

http://www.balundesigns.com/servlet/the-66/6-cln-1-balun-designs-feedline/Detail

Phil - AC0OB
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"What kind of Koolaid do they make you drink in the Physics Department?" Charlie Epps to Dr. Larry Fleinhardt, NUMB3RS   Smiley
K1ZJH
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« Reply #4 on: July 13, 2010, 11:40:29 PM »

Why a 6:1 current balun? without any antenna details it is hard to say what would work best. I'd opt for the best 1:1 current balun between the open wire and coax that I could find-- if the antenna is going to be a 100-foot open wire feed dipole for multiband use.

Pete k1zjh
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KC2YOI
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« Reply #5 on: July 14, 2010, 12:51:19 AM »

 Pete , Phil,  I should have been more specific as to what I'm running here. The feed is about 65' of 6" spaced ladder line feeding a 135' dipole.

I was hoping to run this tuner as it would eliminate about 3 jumpers, 2 switches and an external SWR bridge.

The power rating is closer to what I would expect to need, not as marginal as my 275 Matchbox ( not that I don't love my 275 ).

The balun I was hoping to avoid would be at the tuner end, as on the later 7 series Drake tuner. ( it was an option on the 7 )

My hope was to tap into the network and install the 2 insulators, as on the J. mtchbx linked coupler.

I need to work on my tuner theory here me thinks.

I'm not sure if this sheds light.            Thanks much for the input, DJ
                                          
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K1ZJH
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« Reply #6 on: July 14, 2010, 09:27:47 AM »

At 135' you'll be near reasonance on 75 meters, so you don't need a 4:1 or 6:1 balun for that band. Most of the baluns supplied with tuners are voltage baluns.  I'd still go with a well designed 1:1 current balun for what you're  doing.  Just my opinion, and I am not an antenna guru by any stretch Smiley  Besides,  I'm not sure how you'd convert that tuner to a balanced design without a lot internal rework.

My antenna will hopefully be a 100 foot dipole as many here seem to favor, feed with homemade open wire, to a DX Engineering 1:1 current balun, then my Dentron MT-3000 tuna. Saving up for the plastic spacers, rope and other sundry items that are all overly expensive these days.

Pete
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KC2YOI
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« Reply #7 on: July 14, 2010, 06:47:01 PM »

Pete,
Yeah, it looks like a poo poo for the MN-2000 here  Undecided

I really like the quality of construction, multiple functions and looks of the Drake but the silence here is deafening and I'll take it as a no confidence vote in the idea  Wink
 
I'll concentrate on a link coupled breadboard tuna and try to incorporate some of the features I like in the Drake instead.

re: your dipole project:

Look up some of the answers to my recent threads & you will find lenghty discussions, good links and ideas to do with Dipoles and feeders.

I ended up with something I really like that seems to tune & propogate well.

As far as material cost and availability, the more of a hurry your in, the more wompom you will lay out. Some corners shouldn't be cut though as far as $.

                                                         Good luck manno,   DJ

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