Mods I Have Made To My Kenwood TS-590s

Mark's TCXO Board

See this site for my TCXO Board: https://sites.google.com/site/markstcxo/

External SDR Connection

I wanted to add a connection to an external SDR to my TS-590S to provide a panadapter. The TS-590SG did add an output, but there is none on the TS-590S.

There are many ways to connect an external SDR to the TS-590S to get a panadapter. There is no right way, only the way that works for you best, depending on what you want to accomplish. You do have to make some modifications to the radio.

K3WYC Presentation

Andy, K3WYC has a detailed pdf presentation on panadapters, including much more info on connecting the SDRs and the software available to download here: K3WYC Presentation

Signal Tap Points

IF Tap Points

If you want to connect to an IF test point, the issue is that the TS-590S uses both upconversion and downconversion, depending on band and bandwidth settings, so there are two test points, one for each. If you have a cheap panadapter, with poor unwanted signal rejection and no filtering, this may be a good option, but it will only work if the radio is in the mode using the IF test point you choose. To protect the SDR and your expensive Kenwood, you should use a buffer board with high impedance in and 50 ohms out. This will keep it from loading down the internal test points, and if you static zap the output, you likely will not damage the radio. I did not choose IF outputs, as I am using high performance panadapters, and wanted to use it all of the time.

RF Tap Point - CN101

You can connect to one of two RF test points, before or after the first RF amplifier. If you connect before, to CN101, no other mods need to be made to the radio except adding a buffer board, powered by a voltage you tap into in the radio. I did not choose to do this, but most of the information below applies. The jumper on the bottom of the board is not necessary, and connect to CN101 instead of CN201.

RF Tap Point - CN201

I chose to connect after the first RF amplifier, to CN201. This provides the advantage of a better noise figure, and you get the signal after the bandpass filters of the radio. The buffer boards have poor noise figure, but the radio's RF amplifier is good. You may want to see the whole spectrum, many MHz wide, in which case this will not work as the bandpass filters limit you to the band in use.

I used a Clifton Lab's buffer board. Unfortunately Jack, the owner passed away and DX Engineering announced they bought the rights to make the products, Their website now says they will have an updated buffer board available in December, 2017. The G4HUP board looks similar. I purchased the kit with the board, coax for the input, coax with an SMA panel jack for the output, and set to 6.7 dB gain.

I connected the Clifton Labs buffer to CN201 but had to add a jumper on the bottom of the board, which you may not want to do. I am using a Perseus SDR, which is pretty high end, but lots of others work too, depending on how good you need it to be. The cheaper ones will not have the filtering to reject interfering signals. The Perseus is as good or better than the TS-590S receiver.

Modification Details - Jumper

To add a connection to CN201, a jumper has to be added so the full signal is present there. Otherwise the signal at that point is attenuated by R244 and C241. So a jumper needs to be added across those two parts. This jumper is on the bottom side of the TX-RX Unit. I removed it following the instructions in the TS-590S service manual. A view of the bottom of the board is shown here.

I then added a jumper as shown here just above "PRE0".

I then re-installed the board.

Modification Details - Buffer Amp Power

The buffer amp requires power. I tapped into the 12V in the radio, which is available at a connector on the TX-RX Unit. I spliced two wires into the red and black wires going to that connector. Red is +12V and Black is Gnd as shown here.

Modification Details - RF Tap CN201

I connected to CN201, which is nicely marked Hot and Gnd. I connected the coax that goes to the buffer amp input to a 2mm connector, and plugged it into CN201. Note that this is NOT a 0.1" connector, it is smaller. The connection to the RF tap is shown here. The rear panel of the radio is on the right of all these photos.

Modification Details - RF Tap CN101

I did not use this but many connect to CN101, which also works well. Andy, K3WYC provided this photo of a connection to CN101. The coax center conductor is from CN101 pins 1 and 2 so the jumper is retained and the ground is from the screw near it. The rear of the radio is to the right. CN100 has been temporarily unplugged so you can see CN101. It is plugged in for normal operation.

Modification Details - Rear SMA Connector

The buffer board output goes to an SMA panel jack. I carefully drilled a hole in the rear panel, making sure not to get any shavings into the radio, and installed the SMA jack as shown here.

Modification Details - All Buffer Board Connections

All the buffer board connections, power, input and output are shown here.

Putting It All Together

I then put shrink sleeving on the buffer board and placed it in the radio. It is just held in by the wires and the fit of the shrink sleeving with the things around it. Here is a picture of the finished MOD.

Notes

This SDR Connection Modification is based on this posting: http://uncle-ziba.livejournal.com/7967.html.

I have some high resolution photos with notes at.

https://goo.gl/photos/Xj5MzV1iZNcgTbEi6

There are also a few photos and scope captures related to the ALC MOD there.

Google seems to present these photos in lower resolution on the web page at times. If you download them you can see the high resolution version.

MODs to add and SDR for a panadapter has been discussed at great length in these groups.

Go to the two TS-590's group's pages.

https://groups.yahoo.com/neo/groups/KenwoodTS-590/info

and

https://groups.yahoo.com/neo/groups/TS-590S/info

now replaced by:

https://groups.io/g/TS-590

and

https://groups.io/g/TS-590S

and put "CN101 CN201" in the Search Conversations box, and you will find several conversations, including my posting about advantages and disadvantages of each connection.

This posting of mine explains things somewhat.

https://groups.yahoo.com/neo/groups/TS-590S/conversations/messages/4900

https://groups.io/g/TS-590S/topic/16922973

Here are some of my other sites:

Modifications to my RV, including solar power and extra storage: https://sites.google.com/site/marksrvmods/

My Controleo2 based SMT Reflow Oven: https://sites.google.com/site/markscontroleo2build/

My TCXO Boards to replace the SO-3 in Kenwood TS-590 radios: https://sites.google.com/site/markstcxo/

An explanation of various TCXO Characteristics in Kenwood TS-590 Radios: https://sites.google.com/site/markstcxomeasurements/

Modifications to allow use of an external clock in a Perseus SDR: https://sites.google.com/site/perseusmods/

How I use Spectrum Lab Software to do frequency measurements: https://sites.google.com/site/spectrumlabtesting/

Pictures I took of the 2017 Total Solar Eclipse from Menan Butte, Idaho: https://sites.google.com/site/marks2017eclipsephotos/

Revised July 7, 2020