Something for you CW types

You know, I have to confess: CW isn’t my favorite operating mode. It’s ok; sometimes I tune down to the CW portions of the ham bands and copy it for a while just to keep my hand in, but not too often. Consequently, another confession: I’ve not looked really hard into SdrDx’s CW handling until today. When I did, I found there were improvements that could be made, and, because I’m somewhat compulsive, I went ahead and made them, and you’ll find them in the 2.12r OSX beta that’s available for download as of right now. But don’t stop reading yet, please.

My old J-38 straight key

The first thing I did was some work on the high and low adjustment ranges of the CW mode demodulator envelope; CWL now allows from -10 to -1500 Hz, CWU allows from 10 to 1500 Hz. These are sane ranges; previously, it was a little weird, and I apologize for that.

The second thing was change the demodulator envelope adjustment from 100 Hz/step to 50 Hz/step. This allows you to create a properly centered demodulator envelope of an odd width, such as 300 Hz, or to cut the bandwidth all the way down to 50 Hz — a little extreme perhaps, but amazingly usable if the received station is stable.

Lastly, I experimented a bit with the audio notches to see how to best tailor the audio, and I found that with the Q of a notch set to about the third hashmark from the right of the Q scale, the notch was narrow enough to sit right on the upper edge of the demodulator envelope. I’ll give a detailed example:
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Waiting for the new Mac Pro

A

Waiting...

Waiting…

pple announced a new Mac Pro today; twice as fast as the current model, which itself is faster than the one I presently own. But that’s all they did. Announce it. It’s not ready, there’s no date, there’s no price, and other than “faster” and “supports three, 4k displays” and “much smaller footprint”, there isn’t much other information either.

Sigh.

On other fronts, they’ve finally fixed the multi-monitor shortcomings in OSX; menus, full screen apps, etc. Kudos. Even iOS got a little love with folders that can hold many files, instead of just a few.

The new OSX makes me willing to go for a new Mac Pro, or at least, it seems that way with the limited information I have now. I can put the old fella up in the ham shack where it will do a fine job with the SDR up there; and the new hotness will (of course) drive my desktop, save me time on compiles and just about anything else… and I admit, I run my SDR from my desk even more often than I do in my ham shack. Not just testing, I like the sound of a radio in the background.

The question is, newest model that can only run three displays and has only a small internal SSD? Or the current generation that can do more displays and has room for standard internal HDs?

Apple really does test my patience. It’s been several years since they really gave the Mac Pro much attention, and frankly, I was getting close to building a Hackintosh or buying the current generation. Will they get the Mac Pro out in time? Should I go for newness, the current generation, hacking, or something used off EBay? I feel information-deprived.

Tune in this fall for the next installment of “As the Apple Worms.”

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New OSX and Windows version of SdrDx: 2.12q

SdrDx 2.12q adds full gain support for the AFEDRI SDR, Two additional features, control volume with SHIFT page up and SHIFT page down, and s-meter can readout pre- or post-attenuator. See the link to the changes document, below.


  Screen shot: http://www.flickr.com/photos/fyngyrz/8675326983/in/photostream/lightbox/
    Downloads: http://fyngyrz.com/?p=915
Documentation: http://fyngyrz.com/sdrdxdoc/sitemap.html
      Changes: http://fyngyrz.com/sdrdxdoc/changes212.html

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New OSX and Windows version of SdrDx – 2.12p

SdrDx 2.12p adds support for the Andrus, FunCube Pro Plus and AFEDRI SDRs; It also provides various features and fixes. See the link to the changes document, below.


  Screen shot: http://www.flickr.com/photos/fyngyrz/8675326983/in/photostream/lightbox/
    Downloads: http://fyngyrz.com/?p=915
Documentation: http://fyngyrz.com/sdrdxdoc/sitemap.html
      Changes: http://fyngyrz.com/sdrdxdoc/changes212.html

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Just a story from /dev/random

the-zaWhen I was a kid, we had a wonderful, wonderful pizza place about 9 miles away from home. It was in the little town of Port Jervis, NY. No tables; strictly order in and carry out. This pizza was, and I am so, so serious here, just the best. Perfect every time.

So this one time, my mother and I were out in the car waiting for our order, across the street a little bit diagonal to the pizza place, right next to the Texas Hot Dog emporium. A roller grill, the usual range of hot dog goodness, but after all… hot dogs. We were not there for hot dogs. It was summer, and our windows were down.
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New WordPress version, new MySql version, hoop jumping, aggravation

So, my legions of loyal visitors (notice how I don’t assume you read any of my drivel, just that you visit), my hosting provider informed me that things were changing, and I’d have to update what database I was using and what version of the underlying language, and that also meant new blogging software, and so… the site was down for half a day or so while I located the hoops, jumped back and forth through them, and towards the end, contemplated setting them on fire.

But it’s done now. I think. Perhaps.

However, should you encounter weirdness, by all means let me know and I’ll see if I can work out what I did wrong, or whatever. Sorry for being down, wasn’t my intention.

Cheers!

–Ben

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Marantz MA700 troubleshooting

I have quite a few Marantz MA700′s; of the group, four of them exhibit random popping sounds of moderate energy at the speaker output with no audio input to the unit. Clearly this is a very common failure mode for the MA700.

I have opened one of the “poppers” up on the bench, and with the buffer amplifier signal cable to the power amplifier disconnected, the popping noise remains, so it’s definitely not in the audio path on the buffer amplifier board. The buffer amp is connected to the power amp via an electrolytic, so there’s no problem unplugging the buffer from the power amp.

There’s another problem with this unit, too: I see somewhat random engagement of the high power rail mode for the amp, but this is not co-incident with the clicking coming from the speaker.

When the high/low power state switches randomly, the associated relay clicks, which is audible at very low volumes, and this is obviously not the design intent. Erratic high/low power switching problems are going to be nearby QU05, very likely the electrolytic CU08, the diodes DU01 and DU02, or QU05 itself. I’d suspect CU08 first.

The main amp PCB shows evidence of excessive heating towards the front of the chassis, where the driver section is located. Unfortunately, it looks to me that the mechanical assembly is complex with regards to the main amp and attached heat sink; taking it apart looks to be quite a big deal, my vision has become very poor, and I don’t actually need the amp, so I’m just going to close up. However, at least this exonerates the buffer amp and provides a pointer as to how to troubleshoot high/low rail power issues.

If anyone locates a specific component that is responsible for the clicking and popping, I would very much appreciate hearing about it; I’m willing to hack in a replacement electrolytic from the component or solder side of the board if that’ll solve the problem. Likewise, if circumstances lead me there — if one of my working MA700′s fails and I really need to fix one of these “poppers” — I’ll post what I’ve learned.

I’ve put the service manual for the MA700 online here.

–Ben, AA7AS

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WLO RTTY News Feed Replaced with Weather

Sad news for RTTY SWLs, WLO’s newsfeed at 8472 kHz is gone, replaced with weather broadcasts. The weather broadcasts alternate between RTTY and SITORB, just as the news feed did, but that’s the end of the similarity.

Well, it was nice while it lasted. Sigh.

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