Using 2 meters with the 6700

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So the way I understand it, 2 meters on the 6700 requires an additional 30db preamp for RX along with external filtering.  The output from the 6700 is between 0-5dBm.  That's only about what 1 mw?    At present, I don't see that this is usable.  First off, it would require more than a single amplifier to get to any usable output and an external 30db preamp is just another piece of equipment lying somewhere on the bench or mounted at the antenna.  At this point, I'm unclear as to why 2 meters was included on the 6700 and especially puzzled as to why it was advertized as one of the bands of operation.

Is anyone using their 6700 on 2 meters?  How have you got it configured and was the effort worth it?   I'm considering a 2 meter transverter but that would certainly make the 2 meter band option in the 6700 a worthless option, no?

Norm - KL7RS
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Norm S

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Posted 4 years ago

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Terry, W0VB

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Norm,

Early on I decided that I wanted to use the 6700 directly on two meters - without a two meter transverter.

In July of 2013, a few of us got together, with Steve from Down East Microwave Inc., and defined the requirements of such an amp for the 6700. One that would take 1 mw and produce some serious drive level.... 25 to 75 watts of output.

Steve built such an amp for me - a high powered brick (75 watts out).  Inside the brick is a preamp, sequencer, relays to allow one "antenna connection", and one RF connection for the 6700 XVTR connector..... there's a few other goodies in the box as well, see his specification sheet.

I happened to visited Steve two weeks ago and he says the amp is available with power output levels from 25 watts to 75 watts.

I have been using the 6700, this DEMI amp, and a grounded grid triode giving me 1,500 watts out since September of 2013....  without problem. 

The setup is:
- using the 6700 XVTR jack
- connected to the brick,
- connected to a QRO amp, (grounded grid triode - 1,500 watts out) 
- connected to the antenna. 

I am COMPLETELY HAPPY with this setup. Been using it on meteor scatter for sometime now.

The other reason for two meters in the radio.... and probably the main reason - is to provide the ultimate I.F. for the UHF bands and above. Transverters for 1,296 Mhz and above.

Remember, the Flex6K panadapter can display over 12 Mhz of signals on the display. Most transverters use the 28 to 30 Mhz frequency as the I.F. ..... which is providing only 2 Mhz of band coverage.

This is one man's configuration that is working extremely well..... AND..... the cost of DEMI's brick is much less than the cost of a good transverter.

Reference:  http://www.downeastmicrowave.com/
(I have no financial affiliation with DEMI, just a long time customer)

Terry, W0VB
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Norm S

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Terry,

Can you tell me how good the filtering is on the 2 meter band?  For some reason, I am under the impression it is not very good.  I'm not sure where I got that from though.

Norm - KL7RS
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Norm S

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Terry,

I've got my new 2N75 LDPA and it works just great.  There are two odd things about it though.  I've got a call into Down East on both issues, but thought I'd ask if you were experiencing either of these....

1)  The fan runs as soon as the amp is connected to a power supply regardless whether the Power switch is in the on or off position.

2)  When the power switch is in the off position, it appears the antenna is no longer connected to the rig via the transverter port (no pass through).  So, if you want to leave a panadapter sitting on the 2 meter band waiting for any activity or opening (this could be days), you also have to have the amplifier powered up!

Am I missing something here?

Norm - W7CK

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W5UN_Dave

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Terry, I have been looking for such amplifier as you describe for my 6700 2 meter operation. I cannot find it in the DEMI catalog. Can you give some help? I would order this tomorrow!

Dave, W5UN
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KY6LA - Howard, Elmer

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Me too
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Terry, W0VB

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Dave,

Just call DownEast.... they most likely haven't had the time to put it up on the web. I just visited with them two weeks ago.

Note:  you can order it with separate two meter antenna connections. 

I chose a relay internally so I could run the 75 watts standalone.... Or switch the QRO amp in for full output when needed.

They provide several models.... up to 75 watts output

Good luck, let me know when you're operational.

Terry,  W0VB
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Stan - VA7NF

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There are three threads relating to the 6700 and the transverter; Steve was open to suggestions.

I also am interested in a simple power amplifier for my 6700 on 2M but there is a need for more integration:

Transverter hardware and SmartSDR integration with:

2M In/Out - This power amp and no changes to SmartSDR is a start, but much more is needed.

A VHF/UHF transverter controller that interfaces with enhanced SmartSDR and the 6700 that either uses any (or multiple different) 12MHz slices as concurrent IF feeds assigned to different UHV bands.  Coupled with SmartSDR changes that display real frequencies on the display. 

I'm new to modern methodologies for VHF/UHF so have no experience behind suggestions;  I do envision a stack of integrated inverter modules that concurrently communicate with SmartSDR and display multiple slices.  SmartSDR can also direct via TX indicator which slice/transverter module is directed to transmit.

Can some experienced high band users help guide Steve's design choices for the upcoming 2M and above support.  There is so much more than just 2M FM support here.

73 - Stan  VA7NF



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KY6LA - Howard, Elmer

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The Amp for the 6700 is live on their site http://www.downeastmicrowave.com/PDF/LDPA_PD.PDF  Price is $380 for the 75W version

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W5UN_Dave

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They just put the amp on the web site this morning
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Larry Davis

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i got one works great i order the 222 and the 432 from down east now
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G4YDO

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I've also ordered this amp from Steve, been told the is a 3 months wait.,
(Edited)
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W5UN_Dave

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I was told "4 to 6 weeks"
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Larry Davis

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yes mine took 5 weeks i think
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W5UN_Dave

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Norm S

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Terry or anyone able to answer:

Okay, boy do I feel dumb.   I called and talked to the folks regarding the amp and was told there is an option for an internal relay.  Even after talking to them, I'm not quite sure what the relay is for and if I would want that option either now or for in the future. Its an additional $75 which is not an issue, I just don't want to order with or without it and regret it later. Can someone explain?

Terry, you mentioned that it can be ordered with separate two meter antenna connections.  I don't understand exactly what this would be for.  I'm assuming it comes with a single antenna connection and there is an option to have a 2nd antenna?  How would you select it?  Did you order yours with separate 2 meter antenna connections?

Norm - KL7RS
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Norm S

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Can anyone comment on the two options for the amp?  I'd really like to get this ordered first thing in the morning.  Just not sure if I should get the internal relay option and or the dual antenna connections (separate TX/RX).

Norm - KL7RS
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WQ5C - Mike

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Most likely, you will want the option, assuming you want to run a single feedline to the antenna.  Without it, you would need to run 2 feedlines & mount the T/R relay at the tower.  This is most commonly done by EME stations where they are running QRO with mast-mounted pre-amps.

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Norm S

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I don't ever plan on running EME but QRO may be a possibility.  If I order both options, relay and TX/RX antenna connections, is it still possible to use the amp in a conventional manner such as having the amp in the shack and a single antenna for both TX/RX?  

All of you folks who have already ordered one of these, what options did you ask for and why?

Norm - KL7RS
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Norm S

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Never mind, I finally get it.  I ordered with single antenna connector and HP Relay Option which is the TR/RX relay.  I'm also ordering the remote on/off option.  The folks at Down East said that the remote on/off option can be used as well as the on/off switch on the front panel.  I thought this would be a good option in the event I'm ever able to use the Flex remotely across the internet.  I also asked for the larger heat sink option which is recommended if running digital modes.  I figure extra cooling never hurts.

Now waiting 8 weeks to get it is going to be tough.

Norm - KL7RS
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Greg

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This is good news. I emailed DEM about this some time ago and gave them Tim's info as an initial contact at FRS. I did not realize they had a product already. Cool! Break out the plastic. :)

I would like to use it on FM as well. Any ideas when the 6700 will have FM along with PL tones for repeaters?
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Norm S

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FM is on the road map for October of 2014.  I don't know if it includes the PL tones or not.

I don't use repeaters very often and have a dedicated rig for that.  I mostly play on simplex, both SSB and FM.  I'm really looking forward to the amp but now the October release of SmartSDR with FM seems like a long long time from now...... 

Norm - KL7RS
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Norm S

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Question for the folks at Flexradio.

I purchased a Down East 2N75 LDPA and am extremely happy with the performance. 

The problem is that Field Day is just around the corner and there are a few problems with the SmartSDR on the 6700.

When using 2 meters along with a 2nd panadapter, that is in any other band, the software is unstable.  RF output power is not always remembered (dangerous for amps), and selecting antennas as you move from one panadapter to another is not remembered.

MY QUESTION TO FLEX is:   Is there any possibility there will be a software release between now and FieldDay that will address any of these issues?   I'm reluctant using the 6700 during field day this year due to some of these issues as there will be ops that are not real familiar with the rig wanting to get on the air with it.  A special release just prior to field day would be wonderful news....

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Stan - VA7NF

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Also using the 6700 on FD (TX on 6M through Ant2 and 2M through XVTR + 2N75 and RX on 4 more bands via Pixel loop).  I noticed no feed through on power off but the fan only runs after a transmit.  It is, however, very quiet; I'm using the large heatsink option.
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Mike - W8MM

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IIRC, any time one is using 2 meters on an SCA, that SCA cannot be used for other bands.  This is because one is using different filters to "up-sample" instead of "down-sample" according to different Nyquist zones of the SCA.

So, one SCA dedicated to 2 meters and the other SCA can do up to 4 bands below 77 MHz.
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Norm S

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Yes, I'm using a Flex 6700.

As far as I know there is no way to select a particular SCA.

I've tried all sorts of combinations when creating panadapters.  None of the combinations seem to provide reliable operation when using 2m in any panadapter. 


I've started with my first one by I select XVTR under antenna and then under Band I select 2m.

I then open a 2nd panadapter.  It automatically creates a panadapter based on the first one.  XVTR and 2m.   I then change it to ANT2 and 6m. (this is where my 6m antenna is connected).  Sometimes I have a devil of a time getting it to switch either the XVTR or 6m.   Once it's working, I go on to the next step.

I then open a 3rd panadapter which once again automatically opens up with XVTR and 2m.  I try my best to get it switched over to ANT1, and 20m.

I then open a 4th panadapter.  Same thing - I have to fight it all the way.  Eventually getting it set up for ANT1, and 40m.

Now if I go back to 6m, it will automatically switch the antenna from ANT2 to ANT1.  I get it set back to ANT2 and all appears well, I move to the 40m panadapter and the antenna switches to ANT2. 

Its a constant battle.  Most of the time when I switch panadapters, the panadapter that I have setup for 2m pretty much goes dead.  I look and the preamp and discover the settings changed.

Sometimes the RF power goes to full, which is a real drag for my amplifier which only takes 18w to drive it to full output.

Every time click on a slice in a different panadapter, I have to look at both the T/R ANT, RF power and preamp settings.

Are you folks experiencing any of this or is it just me?

Norm - W7CK

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Norm S

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Shoot, part of my problem is that I'm trying to use 3 antenna inputs.  XVTR, ANT1 & ANT2.  Only one antenna can be assigned to an SCU at a time!

When I'm using 2m and have it configured for XVTR, that particular SCU will now only work with the XVTR antenna input.  So that particular SCU will be dedicated to 2m only.

The remaining panadapters will be using the second SCU and can only be assigned to ANT1 or ANT2 but not both.  No mixing and matching ANT1/ANT2 on the other 7 panadapters.

I don't see any way to use the XVTR T/R ports for 2m, ANT2 for 6m and ANT1 for all other bands.  At least not all at the same time.

STAN:  you said - "I put 2M (XVTR) and 6M (Ant 2) on one SCA and the Flex switches the antenna correctly".   I'm not sure how you do that since a single SCU can only have one receive antenna connected to it at a time.  It would appear you could not monitor both bands at the same time?

Can anyone else chime in here and help me understand this a little better?

Norm - W7CK 

 


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Tim - W4TME, Customer Experience Manager

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I don't see any way to use the XVTR T/R ports for 2m, ANT2 for 6m and ANT1 for all other bands.  At least not all at the same time.

That is correct, there isn't a way to use three antennas for receiving st the same time. There are only 2 SCUs and therefore you can only have two active RX signal paths in operation at one time.
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Mike - W8MM

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One could use an HF/6-meter duplexer attached to a single antenna port and let the duplexer sort out which bands from which antenna proceed to the rig.  

Duplexer common port to 6700 Antenna Port, duplexer 6-meter port to 6-meter antenna, and duplexer HF port to HF antenna.

Simple!
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Drax

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Avoid the MFJ-4275MV power supply and your Flex 6700.  Mine puts birdies every 2 kHz and raises the noise floor 12dB on two meters.  I switched to a linear supply and they went away.
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Norm S

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Good advice Drax.  I avoid all MFJ stuff.  I only own one of their products. Its their 200w auto antenna tuner which works fairly well for camping.

As far as power supplies go, I've run all of my 12v gear off of Golf Cart and other deep cycle batteries for over 30 years and have never had any problems.  Until recently I used high quality chargers to keep batteries topped off.  About a year ago I switched to two 140w solar panels and a PWM charge controller which does not produce any birdies.  I've tried the newer, highly hyped up MPPT charge controllers but all four chargers that I tried were terrible birdie generators and I could never quiet any of them down.  I even worked with the great staff at MidNite Solar while beta testing on of their products called "The Kid" which is a MPPT charge controller.  We were just never able to quiet it down while installed a my particular location.  Some folks might not have a problem if they are able to have adequate separation between the solar system and their antennas and radio equipment.  The MPPT charge controllers turn the panels and the cables coming from the panels into a giant noise radiating antenna.

Sorry for the rant, you are correct though! 

(Edited)
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Keith Ferguson

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I'm doing exactly what Mike, W8MM suggests, but for 70 MHz (in the UK) and with a 6500. I combine the 70MHz receive antenna with the HF antenna in a diplexer, which lets me monitor 5MHz (or any other HF band) at the same time as 70 MHz. I drive a 70MHz PA via the transverter port. The HF antenna is used for HF transmit, the diplexer steers the RF down the correct feeder.

Works a treat.

Keith, G8ELA