Re: [Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[Edward R Cole]

Steve,

Nice article on how you modified the K2 to be a 144-MHz IF for use 
with mw transverters.  The venerable IC290R was used by many for a 
long time.  I hear of some using the FT-817 which is selectable on 
144-MHz output for 0.5/1.0/2.5/5.0w.  I had one that I used to drive 
a DEMI 10-GHz transverter with either 0.5 or 1.0w.  But when the KX3 
came out I could see it was way superior radio to the FT-817 and 
makes a nice 144-MHz IF by addition of the 2M module.


I now have a 2w PA on 10-GHz which drives well with the KX3-2M + DEMI 
transverter (10mw out).


So anyone that does not have a K2 to convert might look at the KX3-2M!


Seriously like the KX3-2M.  It dedicated as mw IF and HF/6m mobile 
operating with KXPA100.  At home is usually monitoring 6m for DX 
openings.  I run a 150w TE linear amp for 2m-SSB mobile with the KX3-2M.


(MI) next August>6m during July CQ-VHFContest>


73, Ed - KL7UW
  http://www.kl7uw.com
Dubus-NA Business mail:
  dubus...@gmail.com 


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Re: [Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[Don Wilhelm]

Steve,

Re: Low Power takeoff point in the K2.

A low power output from the K2 is available if you simply remove jumper 
W6, BUT (and a BIG BUT) is that the power takeoff will be uncontrolled.
You have to drive the VRFDET line to send the power level back to the 
MCU to control the power - the K60XV detects the RF voltage and 
amplifies the DC level with the components in the XVTR ALC portion of 
the K60XV schematic.  So, if you do not use the HF bands, you could 
eliminate a lot of the K60XV circuitry.


73,
Don W3FPR

On 12/18/2017 3:14 PM, Steve Kavanagh via Elecraft wrote:


(2) Using the K60XV transverter interface (W3FPR) - I thought about that option 
and eventually decided against it, primarily because of the extreme sensitivity 
of the K60XV output to RF signals getting into it and causing the K2 receiver 
to shut down (an odd quirk of the circuitry and firmware). Using a modified 
version is an interesting possibility which didn't occur to me - maybe enough 
space could be freed up to build a filter or buffer amp on the original board 
to fix that problem! I do have a K60XV in my other K2 which I have used with 
good results on 50/144/222/432 MHz, but it does require an external filter on 
the output RF jack to prevent weirdness from happening when other nearby 
transmitters are active!


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Re: [Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[Steve Kavanagh via Elecraft]

There's been several good points made about my K2 internal 2m transverter 
project...here's a bit of my thinking about why I went the way I did:

(1) Using an alternate transverter (VE3SYB) - I did consider the Transverters 
Unlimited board from the Ukraine to potentially give me more output, but in any 
case it would require some modification to reduce the output from several watts 
to 100 mW.  In the end, since I had acquired the quasi-DEMI transverter at a 
flea market already, I decided just to go with it.  

I think it would be pushing the state-of-the-art in high-level mixer technology 
to make a mixer which would directly take ~ 1 watt in and produce 100 mW out at 
144 MHz, without either pre-attenuation or post-amplification, but it might 
just be possible.

(2) Using the K60XV transverter interface (W3FPR) - I thought about that option 
and eventually decided against it, primarily because of the extreme sensitivity 
of the K60XV output to RF signals getting into it and causing the K2 receiver 
to shut down (an odd quirk of the circuitry and firmware). Using a modified 
version is an interesting possibility which didn't occur to me - maybe enough 
space could be freed up to build a filter or buffer amp on the original board 
to fix that problem! I do have a K60XV in my other K2 which I have used with 
good results on 50/144/222/432 MHz, but it does require an external filter on 
the output RF jack to prevent weirdness from happening when other nearby 
transmitters are active!

(3) K1WHS interface (K1WHS) - I suspect this is much the same as what DEMI made 
for a while before the K60XV came out (and it was much cheaper than the K60XV, 
too).  N2CEI was nice enough to give me one after they stopped producing them.  
I tried it but decided I missed the full Elecraft-style front panel RF power 
control which it did not support.  I recall Dave telling me years ago that the 
K2 made a pretty good IF radio, so it's been in my mind since then!  I can 
confirm that I too get a group of strong birdies near 145.1 MHz, but as I am 
using 144.1 MHz as my IF this is not a problem for me.

(4) Internal 630m transverter (KE6US) - sounds like a great project! For 2200m, 
maybe not, as one might want better frequency accuracy in such a narrow band 
than the K2 can provide.

73,
Steve VE3SMA
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Re: [Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[David Olean]

Looks good, Steve,

I did something similar a number of years ago. I put a  low power DEMI 
xverter in a pair of K2s but ended up with a birdie that was pretty 
loud  near 145.1 MHz where we had our microwave calling frequencies. I 
ended up removing the xverter and put it in a different enclosure along 
with band switching to select up to six different transverter bands all 
selectable from the keyboard of our logging program.  It was great for 
home station use, but having 144 built in to the K2 box is a nice 
feature for roving.


With our transverter idea, we bypassed the K2 PA circuits and used a 
lower power takeoff point for TX. It drove the transverter just fine.  
As I recall, we had a switch on the K2 to select the low power takeoff 
mode.


I hope to work you some more on your roving trips. I missed last summer 
due to an extended illness, and only recently have I been well enough to 
be active with hamming again.


73

K1WHS (FN43)


On 12/18/2017 4:11 PM, Steve Kavanagh via Elecraft wrote:

For a while now I've been working on a project to install a low power 2 metre transverter 
inside an Elecraft K2, in order to use it as an IF transceiver with transverters for the 
microwave bands.  I got it done this summer and used it on 10 GHz during the ARRL 10 GHz 
and Up Contest, as a "plug-and-play" replacement for one of my aging FT-290Rs.  
I have just finished writing this project up, as it may be of interest to other 
microwavers.  The description is at

http://www.qsl.net/ve3sma/TheK290RProject.pdf .

Happy reading!

73,
Steve VE3SMA
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Re: [Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[Don Wilhelm]

Steve,

You might want to try building up part of the K60XV as part of your 
project.  Download the K60XV manual and its errata and look at the parts 
list - you would need to add the K60XV firmware (and use MCU firmware 
version 2.04 if you do not already have it).  You would not need the 
changes under the RF Board to add 60 meters, nor would you need the 
relay and bandpass filter components in the upper left of the schematic.
You would need the components in the lower right of the schematic so you 
could control the low power output with the power knob.  All connections 
to the K2 are via RF Board J13.


That addition would allow you to remove the attenuator and automatically 
switch in the 1mW output whenever you select a transverter.


You may be able to obtain a bare K60XV board from Elecraft at a decent 
price.


73,
Don W3FPR



On 12/18/2017 11:11 AM, Steve Kavanagh via Elecraft wrote:

For a while now I've been working on a project to install a low power 2 metre transverter 
inside an Elecraft K2, in order to use it as an IF transceiver with transverters for the 
microwave bands.  I got it done this summer and used it on 10 GHz during the ARRL 10 GHz 
and Up Contest, as a "plug-and-play" replacement for one of my aging FT-290Rs.  
I have just finished writing this project up, as it may be of interest to other 
microwavers.  The description is at

http://www.qsl.net/ve3sma/TheK290RProject.pdf .

Happy reading!

73,
Steve VE3SMA
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Re: [Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[Eric J]

Great job! In the pdf you "hope it will help anyone thinking about microwave IF 
rig alternatives." If you can go up, you can go down. I've been researching 
630m solutions to help a friend get on that band. Unfortunately, I think I 
caught the bug. Your solution to microwaves, looks like a way to use my spare 
K2 to get on 630m. The Europeans are far ahead of us there and homebrew 
transverters for 2200m and 630m exist, though they will probably have to be 
outboard and not mounted on the top cover.

Thanks for the post.

Eric KE6US


On 12/18/2017 8:11 AM, Steve Kavanagh via Elecraft wrote:

For a while now I've been working on a project to install a low power 2 metre 
transverter inside an Elecraft K2, in order to use it as an IF transceiver with 
transverters for the microwave bands.  I got it done this summer and used it on 
10 GHz during the ARRL 10 GHz and Up Contest, as a "plug-and-play" replacement 
for one of my aging FT-290Rs.  I have just finished writing this project up, as 
it may be of interest to other microwavers.  The description is at

http://www.qsl.net/ve3sma/TheK290RProject.pdf .

Happy reading!

73,
Steve VE3SMA
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.



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Re: [Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[Kevin Cozens]

On 2017-12-18 11:11 AM, Steve Kavanagh via Elecraft wrote:

For a while now I've been working on a project to install a low power 2 metre 
transverter inside an Elecraft K2

[snip]

http://www.qsl.net/ve3sma/TheK290RProject.pdf


Interesting project. One thing seems a little odd. You use an attenuator to 
reduce the level of the 28MHz signal as it would be too much for the 
transverter to handle. You then say you then need to amplify the transverter 
output because it only puts out 1mW but you wanted 100mW.


It makes me think you could simplify things if you used a different 
transverter that would give you the higher output since you are only talking 
100mW. It could let you eliminate the 28MHz attenuator, the 1mW to 100mw amp 
after the transverter, or possibly both.


--
Cheers!

Kevin.

http://www.ve3syb.ca/   |"Nerds make the shiny things that distract
Owner of Elecraft K2 #2172  | the mouth-breathers, and that's why we're
| powerful!"
#include  | --Chris Hardwick
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[Elecraft] Modifying the K2 for use as an IF radio for the microwave bands

[Steve Kavanagh via Elecraft]

For a while now I've been working on a project to install a low power 2 metre 
transverter inside an Elecraft K2, in order to use it as an IF transceiver with 
transverters for the microwave bands.  I got it done this summer and used it on 
10 GHz during the ARRL 10 GHz and Up Contest, as a "plug-and-play" replacement 
for one of my aging FT-290Rs.  I have just finished writing this project up, as 
it may be of interest to other microwavers.  The description is at  

http://www.qsl.net/ve3sma/TheK290RProject.pdf .  

Happy reading!

73,
Steve VE3SMA
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