Elecraft

Modifying the K2 for use as an IF radio for the microwave bands

Classic

List

Threaded

8 messages Options

Elecraft mailing list

Modifying the K2 for use as an IF radio for the microwave bands

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
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Kevin Cozens-2

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

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 <disclaimer/favourite> | --Chris Hardwick
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

EricJ-2

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

In reply to this post by Elecraft mailing list

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
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]<mailto:[hidden email]>
.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Don Wilhelm

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

In reply to this post by Elecraft mailing list

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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

David Olean

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

In reply to this post by Elecraft mailing list

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:

Elecraft mailing list

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

In reply to this post by Elecraft mailing list

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
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Don Wilhelm

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

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!
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Edward R Cole

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

In reply to this post by Elecraft mailing list

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!
<Wayne: you can just mail my sales bonus - ha ha>

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.

<psst - I will be doing 10G portable mw from Copper Harbor in the UP
(MI) next August><from Longmont, CO RV CG I will be running 500w on
6m during July CQ-VHFContest>

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]