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Author Topic: IC-7600 mod to access the 1st IF for RTL-SDR dongle  (Read 21810 times)

Posts: 3

« on: February 09, 2013, 03:16:02 PM »

Just published an easy mod to make the 1st IF of the Icom IC-7600 accessible. Tapped into the IF used for the built in scope and split the signal. Now, with a cheap RTL based dongle we can use the radio with SDR. All functions, filters etc of the radio still work.


Feedback appreciated

73 Stefan, VE4NSA (VE4SW)
« Last Edit: February 09, 2013, 03:33:49 PM by VE4SW » Logged

Posts: 2835

« Reply #1 on: February 09, 2013, 05:41:49 PM »

Just published an easy mod

Feedback appreciated

73 Stefan, VE4NSA (VE4SW)

This has to be one of the best explanations of a mod I have ever seen. Nice pictures and links to the parts too. Great Job Stefan!!

At this time I do not own a Icom 7600 (have owned the Pro II and Pro III). If I did own a 7600 I would do the mod. It looks simple enough for even an old ham like myself.

Thanks for your efforts Stefan,

Stan K9IUQ

Posts: 3

« Reply #2 on: February 09, 2013, 06:29:36 PM »

Thanks Stan!

Much appreciated.

73 Stefan, VE4NSA (VE4SW)

Posts: 11

« Reply #3 on: February 19, 2013, 01:02:47 PM »

Great job Stefan! 

Good write up, clear photos.

I'm working on the same exact enhancement for my FT-920.  The first IF is at 68.985 and there is a maintenance jack (J1007 for anyone with an FT-920) that allows me to tap it without any other modifications.  I picked up a scrap board at a local hamfest this weekend with Takio-Denki cables on it and hope to have the whole show working sometime this week.  I am using a CliftonLabs Z10000u high impedance buffer (rather than the Mini-Circuits Divider) to avoid loading the IF signal but otherwise it's the same setup.


  - Frank, W8EZT

Posts: 926

« Reply #4 on: February 19, 2013, 01:14:40 PM »

You guys should get together and write an article for QST!

Posts: 3

« Reply #5 on: February 19, 2013, 02:37:06 PM »

Thanks Frank,

I had originally planned on using the CliftonLabs amp/buffer like you. I actually got one However, I tapped into the IC-7600 scope line and still wanted to use the build in scope, that's what made me use the splitter. If you have an unused jack (e.g., maintenance jack), that's probably a good idea. Great thinking of getting an old board with the cables! Let us know how it went and thanks so much for the kind feedback. My next project is testing the different RTL-SDRs (E4000, FC0013 and the R820T) all on the same line coming from the IC-7600. Just got a new splitter with one line in and three out. They all can run on SDR# (three different windows on the PC).

73, Stefan VE4NSA (VE4SW)


Posts: 39


« Reply #6 on: October 15, 2013, 01:04:03 PM »

I hope you post your follow-up soon. I have an 820T dongle, and have just ordered a new IC-7600, and was planning to do exactly what you have done. I am so glad I found your post.

You used the Mini-Circuits ZFSC-2-1 divider. I will use it, too.

I have over 200 of these dividers in stock, new, and sell them on e-bay under my call sign W8ASA.

If you need one, just let me know.

I also have lots of different SMA connectors in stock at Mention that you saw this on eHam and I'll give you a special price you can't get anywhere else.

Posts: 1

« Reply #7 on: March 14, 2014, 11:02:16 PM »


Thank you kindly for posting this! I look forward to trying this out - parts are already on order!

I did have a few questions.
1. Specifically, to the 7600 IF, I am wondering if it is wide enough to populate the whole ~2 megs of the RTL dongles? If not, about how far either side of the center freq will this mod allow me to see?
2. You mentioned in your paper that there is not a noticeable impact due to the loss from the splitter...Over time have you noticed any changes or is it still just as sensitive as you could ask for?
3. Do you find that you have had any issues when transmitting? You mentioned that you do a lot of data modes. Did you need to add any ferrites or chokes to the USB line?
4. Do you have any issues with additional noise being introduced by the additional runs of coax which exit the radio chassis?

A comment regarding the "delay" you mentioned. That is due to the processing delay that exists in the RTL chips, the serialization delay, the buffering in SDR#, any DSP plugins you are running, and then the DA delay to pump it to the sound card. All of this delay adds up to much more than the little delay added in the 7600 by its DSP chips.

Posts: 538

« Reply #8 on: March 29, 2014, 01:43:59 PM »


I did Stefan's mod almost a year ago and worked with Mario (HDSDR) to get HDSDR working.  In short, I love this mod combined with HDSDR as it is superior to the 7600's native scope.  Per your questions (a) I've not attempted to go 2 megs simply as I don't see a purpose in doing so. I'm looking for decent resolution and the ability to pick out weak to moderate signals among a reasonable bandwidth. (b) Have not noticed any delays. However, I lack any equipment to measure such. (c) the associated cables for the splitter and connection to the dongle are short and RF issues. (d) I spend a lot of time on the digital modes. Have not noticed any issue.

The mod is so easy to do and relatively inexpensive there isn't a huge investment if it doesn't meet expectations.

Hope this helps..

Harry WE1X

Posts: 903

« Reply #9 on: March 31, 2014, 08:52:36 AM »

Hi guys,

I'll put my two cents in....

I've been running the R820T dongle on my FT990 for quite some time. Tapped the first IF at 47 MHz. I picked the signal off thru a 0.05uf cap at the junction of T1005 and T1010 on the RF unit. I run HDSDR. I have experienced no loading of the IF signal due to the addition of the tuner. I mounted an RCA jack on the rear panel to feed the IF signal to the dongle. I was going to mount the dongle inside the radio, but did not want to risk any noise issues from proximity between the two. Regular RG174 coax carries the IF signal from the RF unit to the RCA jack.

I have transmitted on all bands, most modes, up to 100 watts without any lockup or other problems. Monitor signal is through DVI cable. It is great to see the band on the monitor and click on a signal and the radio follows (courtesy of OmniRig).

I've owned a 756PRO and find this much more responsive and faster.

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