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Old 02-24-2015, 11:57 AM
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dewdude dewdude is offline
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Join Date: Oct 2006
Location: Manassas, VA
Posts: 113
Quote:
Originally Posted by Electronic M View Post
10$ a piece! That is less than half of the cheapest price I could find them for last year....I think it may be time to bump that up the buy it list a few notches.
Depends where you buy them. I bought a bundle from NooElec; and I was right at $100 for the upgraded "R820T2" dongle and the Ham-It-Up board with the cable to connect the two, the enclosure for the Ham-It-Up, and a SMA-to-SMA cable. I sent them some great feedback about a customer service rep that sent me links to pages of reviews of these things; and it wasn't a sales pitch; it was genuine "just to help you make the best decision you're comfortable with, even if it's not us"; so they wound up giving me their 1:9 balun for free. This was a premium price; but they do sell good stuff.

there are currently two tuners in these units. the R820T and R820T2; they're both completely compatible with each other, but the T2 is noted for having a bit more sensitivity. The $10 chinese dongles are ok; but it's questionable iff they have any antenna protection.

But, yeah; for what it can do the price is outstanding. I remember just about 5 or 6 years ago looking at some of the SDR solutions and they were all thousands of bucks. When this came out it literally changed the game; and despite the limitations, it's become very popular for projects simply due to the price.

Quote:
Originally Posted by NoPegs View Post
So what if I whack a rough-cut bandpass/high-pass/low-pass filter in the antenna chain? That is to say if I'm cruising the large bands, and I put a brick wall that starts at 12MHz will that assist? (Considering the antenna best matched for those bands is very large, it will pick up every damned signal it can.)

I didn't know there was a Live-CD distro for these. That sounds like it could be very handy. I have several machines awaiting a reason to be used, I can just build off of the Live-CD distro on a laughably small hard drive.

FWIW I believe your FM DX experience is completely within the bounds of possibility. The thing to look for is were there any other stations on that same frequency that logically should have been competing for your RF front-end?
It's possible if you did that you'd get better performance. I know I hooked in to the IF stage of my Sansui 200 and did in fact notice some performance increase on weaker stations. It's often been said these things would do a lot better if you weren't piping such a wide signal in to it. There's a dude on IRC who's talked about this several times; but he's not around to get more dtails about.

There's a Live-CD for them? Doesn't surprise me; but people have said gqrx isn't that great of a program and a lot of people wish SDR# was built for Linux.

Here's what's interesting about the WRDU DXing. I looked up on Radio-Locator as to what was close-by on 100.7. There were no stations within 60 miles. There was a station down south of Roanoke, about 66 miles away putting out 820 watts. That's down in the mountains though; so I suspect that while they had a height advantage; mountains were blocking it. The only other closest station was 73 miles north in the mountains.

It was clearly WRDU 100.7; I was getting RDS data that confirmed this, there's also this: http://dewdude.ath.cx/WRDU.mp3 - and that was literally just a 300-ohm folded-dipole made for twin-lead (which was half-wavelength for 88mhz, so it's a japanese FM band antenna) that was simply attached to the railing (push pins through the holes in the insulators) and running back to my SDR through extra twin-lead and running through the 9:1 balun...I didn't have an F-to-SMA to use a 300-75 balun...not to mention the SDR stuff is 50ohm input. I had zero complaints about that performance.

The question that's burning me is whether there was something going on letting that station come in; or if it was just a LOS thing. The tower down in NC for that station is in a pretty flat area and has a HAAT of like, close to 2000'. From what I could tell on Google Earth; I was about 800ft elevation with a clear LOS down to Raleigh. So...maybe that station in that particular area isn't really a record but just a fluke of line-of-sight.

I was down at my grandparents last month with the setup; they live just outside of Fredericksburg VA. Their kitchen basically sits at the second floor on the back of the house; so I was sitting there with my 1m magnetic whip on the top of the chest freezer. When I was doing a reception log; I actually had to tell radio-locator to start showing me stations past "fringe" because that's what was coming in...I'd stop on a signal...figure out what content it is...look at the list..and nothing. I eventually got the point where I just have it show me FM stations within 200 miles.

I'm not questioning whether I picked up WRDU or something else; I was able to identify it both from a sound clip and RDS data; but it's just got me wondering if it was a crisp winter night that did it; or just the fluke of being on the side of the mountain facing the transmitter with little in between us but air.

As far as stations competing; I don't believe this thing responds to FM-capture like normal radios. I would get ghosts of strong FM stations; sometimes 4 or 5 on the same frequency. There was a time or two I heard two FM's competing...and it wasn't capturing either one. SDR seems to break some rules like that.
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Audio: SMSL M8 -> Little Bear P5 -> Sansui SE8 -> Yaqin MS-12B -> Denon PMA-770 -> Ohm Model L | Ham: NQ4T - IC-7300
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Last edited by dewdude; 02-24-2015 at 12:00 PM.
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