6700 on 2m

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  • Updated 2 years ago
As I understand, the. 6700 can operate 2m directly at mW levels, so you really need an amp. The alternative is to use a transverter which already has the amp. What are the pro's and con's and what hardware are other flexer's using for 2m with the 6700?
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Mark Erbaugh

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Posted 2 years ago

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Burch - K4QXX

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I will eventually be using the Down East Microwave 2MLDPA.  It's made for the 6700 and has a pre-amp and 75 watt output.  You can order it with or without the remote option.  I ordered mine with the remote option which lets you control the amp and pre-amp from SSDR.  I have had the amp almost a month and am waiting on SSDR 1.10 to be released as you can't use the amp without it.  If you order without the remote option, you can use it now with the 6700 or any other low output 2 meter source.


Burch

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Tim - W4TME, Customer Experience Manager

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LDPA advantage: No RF mixer involved, so there are no mixing products to filter out (a cleaner signal).  No oscillators needed for the mixer, so frequency stability and accuracy is also not an issue.
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Norm - W7CK

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Tim,
Is there a way to adjust the frequency error on 2m while using the LDPA method?  My slice display frequency seems to be off a bit.
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Tim - W4TME, Customer Experience Manager

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How far off and in what direction (+ or -)?
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Norm - W7CK

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Hi Tim.  I just got home otherwise I would have gotten back to you sooner.

Every repeater I try and all of the simplex frequencies are off about the same amount.  For example if I'm suppose to be on 146.84, I have to actually tune to 146.841.  If I'm wanting to be on 145.410, I have to tune to 145.411.  I know this isn't much, but running weak signal digital modes it becomes a little annoying.

Is there a way to calibrate it?  I'm not using a transverter.  I'm using a LDPA.

Norm
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Tim - W4TME, Customer Experience Manager

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No issue on the delay.  Thanks for the info.  Based on your description where the panafall is ~ 100 Hz low, is an issue already in our bug tracker as defect #3333.  I do not suspect this is a calibration issue. 
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Martin Ewing AA6E

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When I was testing a 6700/LDPA, I noticed something similar.  I put it down to poor frequency control on the repeaters and/or the user's HT.  A 1 kHz offset is not too surprising for "cheap" gear, but I would expect it to be randomly higher or lower than nominal.  (Interesting question: are the repeaters demodulated to baseband audio and then remodulated, or do they just translate the incoming signal?  I suppose the former, since they have to add ID tones & info.)

Of course you need to carefully calibrate your 6700's master oscillator (ppb settings) if you want precise frequencies at 2M.

73 Martin AA6E
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Martin Ewing AA6E

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Another advantage of the LDPA approach: You get full coverage 144-148 MHz.  Most transverters only give you 144-146.
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Tim - W4TME, Customer Experience Manager

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Yes, I forgot that one.  Thanks.
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kk4x

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Use of External transverter other than 2 meter LDPA, would a 2 way coax switch work?, I still want to use the 6700's 2 meter capabilities and want to add  a Transverter. any Ideas??

tnx

Ed 

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Ria - N2RJ, Elmer

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I am probably going to end up with something homebrew based on a W6PQL design using 2 LDMOSFETs for legal limit on 2m.
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kk4x

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life is too short for qrp, Get a BEKO or W6pql AMP

Ed
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philip.theis, Elmer

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Lunar Link's work forever. I have three