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Messages - BoomboxDX

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31
General Radio Discussion / Re: All Digital AM??? An ENG's perspective.
« on: September 01, 2020, 0233 UTC »
From the article:
"Further, once the all digital conversion starts, more and more co-channel digital interference will happen, likely cutting down that contour to a great extent."

Er.... no. By the time the band went all-digital -- that is, if it ever does -- the band will be so thinned out of stations that interference from other AM broadcasters would undoubtedly be a non-issue.

Right now there are AM stations existing on the thin edge of the wedge, financially. If the corona recession continues for another year, more of them may be gone. That's in addition to standard AM audience attrition. So I don't think this engineer guy has to worry about co-channel digital interference.

32
Equipment / Re: To Chuff or not to Chuff?
« on: August 29, 2020, 0549 UTC »
What's a good pair of diodes to use?
I think I may have some 1N919's lying around.

Any diodes will work better than no diodes. I don't remember what I used, probably a couple germanium ones from the standard pack I got from Radio Shack in the 1990's I had lying around. 1N414's or whatever they're called.

All they have to do is drain static discharge from the whip -- when you touch it -- to keep it from zapping the SW RF amp.

Also gives a layer of protection from external antenna static bleed. Of course, in lightning regions, you'd want the radio disconnected from an external antenna anyway during staticky conditions -- be it extra dry winter conditions (when antennas can apparently develop static during wind or whatever) or when there is t-storm activity....

I used hookup wire, soldered the diodes together (reversed polarity from each other), and wrapped the diodes with shipping tape after soldering them together and to the length of hookup wire, to keep them from grounding out on anything nearby. I forget which end the diodes went to (probably the battery negative), and the hookup wire end went to the antenna solder pad on the PCB. I'm going by memory here, but it's an easy thing to do if I can do it, and protects the radio.

33
I left the 803A unplugged for a few hours, and powered on again.  The LW is now back, it goes to LW OK.  But the high pitched squeal on the reception is still there.  Maybe some of the parts inside have gone bad? such as caps or resistors?  That 9V wall wart works fine with the other radios.

I don't know about your radio, but DX440s and 803As had high pitched whine when new.

Your radio probably needed a reset. Sometimes microprocessors on SW portables wig out. My DX375 did that once, years ago.

The 440 is an old model, but the parts shouldn't have gone bad necessarily. I have older transistors that still work well.

It sounds like your radio may have some issues, or maybe just wasn't powered up for a few years. Mine acted funky when I first powered it up after several years' hiatus.

I'd use batteries instead of a wall wart, to be on the safe side. I have two 9 volt wall warts that when I measured them, they put out 11 volts. The 440 is light on batteries... they last a while.

Good luck.

34
Equipment / Re: To Chuff or not to Chuff?
« on: August 28, 2020, 1553 UTC »
Chuff never bothered me on any radio, whether he DX440 or any other SW digital portable.

The whine can be switched off by flipping up the lock switch. That is, once you're parked on a frequency you want.

For mods I would forget the anti-chuff one and add protection diodes between the antenna 'post' and the negative side of the battery. The 803A/440 has no diode protection for its SW RF amp front end. If you're going to dig into the radio I'd do that instead of worry about chuffing....

Good luck either way. Enjoy the radio. SW sounds terrific on headphones on these radios, by the way. Back in 2002-2003 when I was SWLing every AM with my 440 and the bands were still packed it was a dream.

35
General Radio Discussion / Re: Allan Weiner buys WHRI
« on: August 18, 2020, 0448 UTC »
Nice to see Weiner's going to keep it on the air. Some ministries are running into financial difficulty with Covid-19, and I wonder if it's the same with the former owners.

I wonder how long any of these domestic SW stations will remain on the air, though.

36
The DX440/803A doesn't have protection diodes built in, but if you are reasonably good with a solder gun or soldering iron, protection diodes can be wired in using hookup wire and a couple back to back diodes -- or even rigged at the external antenna itself.

MW performance is fairly good but on mine it's much improved by adding an external MW loop.

The "carrier noise" could be the PLL whine, which often will go off if you strike in the 'lock' button, for some reason. On my radio, I never heard it much through headphones. DX the SWBC bands was a dream when there were still signals on the air, the DX-440 has really good audio through headphones.

37
If by "analogue" you mean non-digital tuner readout, sure -- a lot of radios are still good, just as long as they are operating correctly. My Yaesu FRG-7 is still very good on SW and excellent on MW. You get within 5-10 khz using the analog dial readout, which is close enough for SWBC and even most ham listening. On MW it's easier because the MW band is fairly standard -- stations are either 9 or 10 khz apart and if you know the band in your area it's easier to figure out where you are.

Other analog radios of the pre-digital era can have good performance, and the readout still will leave a certain amount of guesswork, depending on the way the radio's tuning scheme is set up -- some of the Panasonic and Sony radios had crystal markers, which would help in tuning.

But the radio circuits themselves were probably as good as most DSP chips in SW portables today. With SW, a lot of it is the antenna, anyway.

Just my 2 cents.

38
Propagation / Re: ARLP029 Propagation de K7RA
« on: July 25, 2020, 1315 UTC »
If the new solar cycle has officially started, it looks like it's more with a whimper than a bang.

39
Equipment / Re: Please recommend some good MW and LW DX radios
« on: July 01, 2020, 0401 UTC »
Thanks for all your info & feedbacks. Great stuff !!
Yeah, I think I will be making something very very simple, something like this I have seen on Youtube.
I think you can buy one made from TECSUN, but that is about 20-30 USD. Why not make something like this which will cost less than a fiver? and works same as the bought ones. :D

https://www.youtube.com/watch?v=yl5t0v9guho

Because a new 365 pf tuner cap might cost as much as a factory made loop? They're getting more and more rare now, especially when most radios are digitally, and DSP tuned. Even used, 'junk' radios are getting rare at local thrift stores here where I live in the US.

40
Equipment / Re: Please recommend some good MW and LW DX radios
« on: June 30, 2020, 0457 UTC »
One thing to remember is that there are still AM/MW loop antennas that you can buy here in the US for around $50 USD (the Eton AN100 is one of them). You just sit them next to a portable radio.

I have two of them and they work almost as well as the crate loop.

41
Equipment / Re: Please recommend some good MW and LW DX radios
« on: June 26, 2020, 0325 UTC »
^^^^^ Sounds like a good plan. And remember, my previous post was off in wire length... 33 meters or so of wire around the box, not .33.

42
General Radio Discussion / Re: CHAZ Free Radio Stations?
« on: June 18, 2020, 0229 UTC »
On a different radio forum it's reported that there are none in the area.

43
RE: phones: according to some activist organizations' PDFs readily available online, phone security (and wariness) is definitely discussed. I suppose this apparent monitoring from the skies is one of the reasons.

44
Equipment / Re: What are you using for SWLing?
« on: June 11, 2020, 0155 UTC »
Alpard -- I also listen to MW at night, and DX the MW when the conditions are good. MW still has plenty of stations and signals here in my corner of the US. I usually listen on one of my Sangeans, and sometimes my GE Superadio. My boomboxes are in storage right now. :-)

45
Equipment / Re: Please recommend some good MW and LW DX radios
« on: June 11, 2020, 0152 UTC »
Even a passive loop will work on MW (and LW). I use a plastic crate that is about one foot square (33 meters, roughly), and it has 110 turns of wire around it, with a 365 pf tuner capacitor to tune it. For LW, one would add more wire. I forget how long a piece of wire it would take -- maybe 30-40 meters of wire, and you cut to fit maybe?

They're easy enough to make if you have the tuner capacitor and wire.

My crate loop boosts any of my MW radios by at least 2 db or more.


Edited to ADD: it's 33 meters, NOT .33 meters, as the original post stated. The ".33 meters" was a typo. Woops.

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