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Posted: 9/26/2016 7:08:14 AM EDT
[#1]
I use them on my IC706's and and TS-430S. The only delicate part is doing the IF tap - esp on the 706's with itty-bitty surface mount parts.
I also use the TCXO version dongle unit for a ham sat receiver. All of these work fine where high dynamic range isn't required. I use HDSDR for all. |
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Posted: 9/26/2016 7:35:30 AM EDT
[#2]
I did it on my TS-140S, and agree that the only challenge was soldering the IF tap. It was really pretty cool (and cheap), but it changed my view on what I wanted in a radio... I upgraded to a Flex a few months ago.
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Posted: 9/26/2016 7:55:35 AM EDT
[#3]
Quote HistoryQuoted:
I did it on my TS-140S, and agree that the only challenge was soldering the IF tap. It was really pretty cool (and cheap), but it changed my view on what I wanted in a radio... I upgraded to a Flex a few months ago. Haven't seen this guy post in a while! 
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Posted: 9/26/2016 10:50:26 AM EDT
[#4]
I have one of These setup for my K3
But I just looked up that your uses a much higher IF ( 67.899 MHz ) so a SDR dongle should work |
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Posted: 9/26/2016 10:57:29 AM EDT
[#5]
590SG has an output for this...made it easy. But it does cost you 3dB, so I usually only bother if I am chasing a rare DX that is moving around his RX a lot. |
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Posted: 9/26/2016 1:44:25 PM EDT
[#6]
Quote HistoryQuoted:
Haven't seen this guy post in a while! Quote HistoryQuoted:
Quoted:
I did it on my TS-140S, and agree that the only challenge was soldering the IF tap. It was really pretty cool (and cheap), but it changed my view on what I wanted in a radio... I upgraded to a Flex a few months ago. Haven't seen this guy post in a while! - Mostly lurking. Been busy...
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Posted: 9/26/2016 4:15:42 PM EDT
[#7]
I have read that people are using isolation amplifiers between the tap and the SDR dongle. Are these necessary?
If not, what components did you use beyond just soldering coax directly to the board in the radio? I have read some solder the cable right to the tap location and others use a 1k resistor, a small ceramic cap, or both. It would be nice to have a radio that makes it easy with a first IF output. Are you guys mounting the SDR donngles inside the radio and feeding a USB cable out, or are you just bringing some coax to the back panel with an SMA connector? I think I have read about it being done both ways. |
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Posted: 9/26/2016 4:36:04 PM EDT
[#8]
Quote HistoryQuoted:
I have read that people are using isolation amplifiers between the tap and the SDR dongle. Are these necessary? If not, what components did you use beyond just soldering coax directly to the board in the radio? I have read some solder the cable right to the tap location and others use a 1k resistor, a small ceramic cap, or both. It would be nice to have a radio that makes it easy with a first IF output. Are you guys mounting the SDR donngles inside the radio and feeding a USB cable out, or are you just bringing some coax to the back panel with an SMA connector? I think I have read about it being done both ways. An Isolation amp is good to use. |
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Posted: 9/26/2016 6:09:27 PM EDT
[#9]
Well, you don't solder coax center conductor directly to the board. I used 4.7 pF for the IC706's, and about 12 pF for the TS430S.
I will be going into the IC706's again as 4.7 pF isn't quit enough coupling. Almost anywhere you tap out, you'll want/need to re-tweek the tuning of that stage. Since these are generally pretty broad at the 1st IF (pre-roofing filter if you have one), you can do it by ear / S-Meter no problem. Note that on the TS430S, some sampling noise gets back into the reciever which, of course, is undesirable. So, if I'm working a weak one, I have to shut down the dongle  - which is a really good reason one might want to use an isolation amplifier. It doesn't seem to have the problem on the IC706's.
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Posted: 9/26/2016 7:52:32 PM EDT
[#10]
We used a .010 cap at the IF tap, and ran a piece of mini coax from the tap to a chassis mount RCA jack fitted in an unused (plugged) hole on the back of the chassis. The coax came from two antennas that came with RTL-SDR dongles... For the run outside the radio, a RCA adapter was soldered to the other piece of coax and the MCX connector end of that one (an old dongle) plugs into the RTL-SDR dongle.
I made a video right after I finished this up: https://www.youtube.com/watch?v=L9JtF1WkQtI |
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Posted: 9/28/2016 1:39:44 AM EDT
[#11]
Quote HistoryQuoted: Well, you don't solder coax center conductor directly to the board. I used 4.7 pF for the IC706's, and about 12 pF for the TS430S. I will be going into the IC706's again as 4.7 pF isn't quit enough coupling. Almost anywhere you tap out, you'll want/need to re-tweek the tuning of that stage. Since these are generally pretty broad at the 1st IF (pre-roofing filter if you have one), you can do it by ear / S-Meter no problem. Note that on the TS430S, some sampling noise gets back into the reciever which, of course, is undesirable. So, if I'm working a weak one, I have to shut down the dongle - which is a really good reason one might want to use an isolation amplifier. It doesn't seem to have the problem on the IC706's.So what I am reading is that the reason for the buffer amp is because the local oscillator in the SDR dongle leaks a little. And the de-tuning in the radio only gets bad if you have a long-ish run of coax from the tap to the SDR. I dont have enough knowledge to look at a schematic and figure out which components to tune so this might not be a good project for me. Linear voltage regulators are about as complex as I can decipher.  |
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Posted: 9/28/2016 1:47:13 PM EDT
[#12]
I can't speak for all installations....
On mine, I tap the output of the first IF transformer / resonant circuit.. So, any length of coax as well as whatever Z the dongle presents, will load and/or detune the transformer severly if just directly connected. So, I tack in a small cap such that loading is minimized and detuning can be re-tuned just by adjusting the transformer / resonant ckt. On the Kenwood, signal levels to the dongle are good enough, but the dongle shoots some sampling noise back into the xcvr. On the IC706's, signal level isnt' quit high enough in order for the dongle to see the noise floor. In both cases, an isolation amp inline would help.....in the first case to eliminate the noise...in the second case to bring up the signal levels a bit. But it may take a while to get around to it - it really works *ok* the way it is, and seeing the spectrum is really cool and useful for pile-ups and finding new ones. |
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Posted: 10/3/2016 10:07:18 PM EDT
[#13]
Well I ordered a couple of the NooElec NESDR Smart dongles, one with the antenna kit, and one without, and they arrived today. Just playing with the HDSDR software, this is going to be really awesome once I get one installed.
I am on the fence about installing a USB port in the radio somewhere and installing the dongle inside the radio cabinet, or just bringing the IF signal out to the back panel via an SMA connector and keeping the dongle outside the radio. |
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Posted: 10/3/2016 10:25:08 PM EDT
[#14]
I'd keep the dongle outside the rig. An IF tap in the form of an RCA or other connector on the back of the rig would make it more versatile as well as keeping a noise source out of the cabinet.
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Posted: 10/3/2016 10:56:35 PM EDT
[#15]
Quote HistoryQuoted: I'd keep the dongle outside the rig. An IF tap in the form of an RCA or other connector on the back of the rig would make it more versatile as well as keeping a noise source out of the cabinet. It would certainly be easier to find a spot to mount an SMA connector than a USB port. |
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Posted: 10/5/2016 12:21:31 AM EDT
[#16]
Quote HistoryQuoted:
I'd keep the dongle outside the rig. An IF tap in the form of an RCA or other connector on the back of the rig would make it more versatile as well as keeping a noise source out of the cabinet. Agreed With it internal to the radio it can create birdies. Also put the sdr in a metal box an use well shielded coax an chokes on the usb cable. |
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Posted: 10/30/2016 6:27:37 PM EDT
[#17]
Well I went ahead and did it.
There appears to be a 20 KHz band near the center that has more gain than the rest of the band, if that makes any sense. Not sure why. Also a spike that stays 25.416 Hz above the tuned frequency no matter where I tune. As far as de-tuning the IF circuit, I am not sure how to discover this. WWV sounds spot on when I tune to 5mhz using just the radio.
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Posted: 10/30/2016 8:20:23 PM EDT
[#18]
Fair warning, start planning now for that Flex or Apache, that shit is addicting 
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Posted: 10/30/2016 8:27:41 PM EDT
[#19]
Nice job! And yes, once you have a panadapter, you'll want more. One of my cheapest ham investments (the dongle) led directly to my most expensive (a Flex).
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Posted: 10/30/2016 8:55:25 PM EDT
[#20]
The cool thing is the OmniRig software that lets HDSDR have CAT control of the radio. Click to tune.
 Still trying to figure out the annoying birdie. |
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Posted: 10/30/2016 9:52:49 PM EDT
[#21]
Nice work!
Put your antenna in the attic, and you will have a shit load of birdies. Ask me how I know. 
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Posted: 10/30/2016 11:32:58 PM EDT
[#22]
Quote HistoryQuoted: Nice work! Put your antenna in the attic, and you will have a shit load of birdies. Ask me how I know. Heh, yeah I did the indoor antenna thing for months and it is a no-go for HF. This birdie is something in the dongle or the transceiver. It follows the tune frequency around no matter where I tune, always the same offset and signal strength. I will have to play with offsets and see if I can make it move farther away from the center frequency. |
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Posted: 10/31/2016 12:01:33 AM EDT
[#23]
Forget all of that SDR garbage, I want my knobs
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Posted: 10/31/2016 12:43:36 AM EDT
[#24]
Quote HistoryQuoted: Forget all of that SDR garbage, I want my knobs I can live without it. But it sure makes finding signals fast and easy. What used to take several minutes of scrolling around, is now a mouse click away. I don't think I want a radio that doesn't have a display and a manual interface. I definitely like having the ability to connect to a computer this way. I just don't want to lose the option to operate without a computer connected. |
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Posted: 11/1/2016 8:36:20 PM EDT
[#25]
Well it looks like the birdie might be something internal in the FT-450D. I only have the cable grounded at the chassis, not at the tap end of the cable. Could this be the cause?
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Posted: 11/1/2016 8:47:49 PM EDT
[#26]
You should ground the tap end of the cable.
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Posted: 11/2/2016 2:28:30 AM EDT
[#27]
Quote HistoryQuoted: You should ground the tap end of the cable. I will have to open it back up and fix that. I am not too happy with the routing of the cable, but it took me probably 10 minutes to get the capacitor soldered in and I didn't want to risk the solder joint breaking, or worse, pulling a trace off the board. I did tin the braid of the cable and put some heat shrink on it in anticipation of having to solder it to something. I can solder to the big shield next to the tap. It could probably use a little dab of hot glue to stabilize things as well. |
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