Cost a boatload of money -- far too much for the barely-existing Ancient Modulation market to bear?
If you want something like that, better to pick up a ham rig with a general coverage receiver built in. You'll need a proper antenna, of course.
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Cost a boatload of money -- far too much for the barely-existing Ancient Modulation market to bear?
If you want something like that, better to pick up a ham rig with a general coverage receiver built in. You'll need a proper antenna, of course.
How about driving by a Daytimer without a PSSA at Night to hear the exciter carrier and "drive the signal"?
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Cost a boatload of money -- far too much for the barely-existing Ancient Modulation market to bear?
If you want something like that, better to pick up a ham rig with a general coverage receiver built in. You'll need a proper antenna, of course.
It's amazing though how much improvement you can get from a small tuned loop or a short vertical antenna with a tuned one transistor preamp. The preamp I built is from Tom Kneitel's "103 Simple Transistor Projects", with small modifications.
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I was a young child and happened to live just a few blocks from the FM radio station to which I had been listening: offices, studios, and transmission stuff.
One day, the station went "off the air", but I heard the DJ and some other station personell including the AM guy and the AM news guy scurring around.
I should not have called the station up and interrupted them, but they insisted that I could not possibly be hearing them because their transmitter was off...
even after I echoed some of their expletives back to them.
You know you might be a radio nerd if... (this really should be a separate thread)
You drive back and forth to find the one perfect spot where that highly directional AM station less than a kilometer away's carrier
totally nulls out and you are left with nothing but loud and crisp, absolutely delicious, purely distorted sidebands,
so you bring other people there to hear it,
and you ponder about whether the house you are parked next to could be bought.
I have always wanted to live right in a directional null.
Nulls are only good if you never listen to that station. One of my favorite stations growing up had a null toward me in the Night Pattern. There was a lot of variation in the signal, and a lot of reradiation. It was fun when they would blast in on omni STA. The station owner's son and station GM lived 1 1/2 blocks away and was always complaining to the CE about the signal. I called the CE once and told him I lived in the null and he said, "doesn't everybody"?
R
rbrucecarter5
Guest
In fact, yes, I have looked at the Silabs data sheet. The important thing to remember is that a data sheet is - above all else - a marketing document. Its job is to sell the chip to design engineers. I know because I have written several for Texas Instruments. It is a constant balancing act between presenting the chip in the most positive possible light, without actually lying which would have legal implications. It is an art, and every engineer designing things develops a healthy skepticism early in their career, or their career doesn't last very long.
I am very impressed with how far DSP technology has come in the past 30 years since I helped another engineer with the very first DSP design in any product. We paid $1000 per device - in 1987 dollars - for advance silicon before the part was released. I am also mindful that the engineer was trying - as desperately as they could - to eliminate aliasing from their design. No matter how complex they made their DSP algorithm - they still had aliasing and were at a deadlock in their design, unable to deliver. In desperation, he asked the token "analog guy" for help. In I walk with a resistor and capacitor, make a one pole low pass anti-aliasing filter - and his design worked. In fact, he could remove all the code he had added trying to make an anti-aliasing filter. To help him save a little face - I went ahead and put in a two-pole low pass filter for him, but two poles weren't needed, only one.
I related that story to drive home a point - some things are better done in analog, others in a DSP. I have a really good DSP implementation of the AM band in my Pioneer Supertuner 3D car radio. It may be Silabs, it may be some other manufacturer. Somebody decided that all AM stations should have audio limited to 200 Hz to 3 kHz. So music on AM is muffled - no chance to improve it at all. Selectivity is really good, but the slew rate of a sports talk station 30 kHz away somehow leaks into the audio of a strong clear 250 miles away. There are stations first adjacent and second adjacent that are completely clear. How I wish that DSP implementation had just used a darn ceramic filter somewhere for stop band rejection! And, the DSP algorithm is not good at tracking rapidly changing signal strength. Thank goodness it just clips power line noise, but the same algorithm also clips audio if a station is rapidly fading in. Yeah - it is sensitive as heck - probably their way of making sure HD AM works. But give me a good analog implementation of AM any day if that is the best the DSP can do.
As to your model of radio using the Silabs chip - I will be happy to analyze it for you if you want to lend it. I am aware of the reputation of the brand, but I am a careful, methodical researcher who goes about these things without preconceptions. I want to test it myself and prove any claims of something being better. Same with the RF-2200 or whatever it is people are hyping up. I am glad it works for them. You want me to agree? Do a shootout like mine, or send me one on loan and I will be happy to analyze under controller conditions. I'll be the first to buy something better if I find it. But when my GE Superadio III is out there meeting or exceeding the performance of my Hammarlund SP-600JX (I'll post that soon) - it will take one heck of a radio to beat them both.
At Bruce, I'm having way too much fun with my HDr-16 to loan it out. But if you do ever get one, I'd still be open to hear your thoughts on it. It's not the best radio out there I'm sure but it has been so much fun for me. I'm like a DX noob compared to you all. LOL
But if you do ever get one, I'd still be open to hear your thoughts on it. It's not the best radio out there I'm sure but it has been so much fun for me. I'm like a DX noob compared to you all. LOLThank you for your thoughtful response.
RE the algorithm not tracking rapidly changing signal strengths... That must be the "slow AGC" I was referring to in my previous post.
ON a GESR3, the signal would fade but you'd hear the static, the background hiss much louder... you know, the RF ether noise that we hear when you tune to an unused channel.
With a PRD5, you can still hear it, but it's like an older boombox with slow AGC, or a multibander from the 70's with slow AGC -- except overall the performance is Superadio-like and in a sense, very very very good. I just wish they'd have ditched the drop down resistors on the headphone socket. But it's an easy fix.
Sorry I can't lend you a PR-D5 or one of its relatives.... Maybe someone in Texas could lend you one. You may be impressed... but you'll see what I'm talking about when I mention it acts like it has slow AGC. But it still is a great DX radio.
I agree with you on the SR3. Some few were excellent. Awesome through headphones, too.
My SR3 came with a 35 or 38K antenna resistor from the factory (I don't remember the exact value but it's much lower than that on the schematic and higher than the value you state on your website as being 'too low'). And so far -- knock on wood -- the tuner works well. Only issue is mechanical backlash, but I can live with that. Love that radio.
Best regards.
R
rbrucecarter5
Guest
I can fix the SR-3 backlash - basically at cost - if you ever want. At the cost of dial accuracy, though. Maybe - somebody at GE/RCA read my tech pages and changed the resistor in production. More than likely, though, a production line mistake that just happened to help.
Just a side note, this a.m. I did a quick comparison between my GE SRII and my Sangean PR-D5 on a relatively weak channel here, 1570. They were neck and neck but the PR-D5 had better selectivity (it's fairly narrow, as many have commented who have this radio) and the AGC characteristics were a little different -- but not as different as I'd thought earlier.
The PR-D5 had the edge in readability when both KCVR Lodi (California, Deportes) and XERF (Mexico, norteno oldies) faded down and back up, implying that it has slightly better sensitivity... but whether it was the raw sensitivity of the PR-D5 or its voicing, I don't know (the SRII has fairly wide fidelity compared to the PR-D5's more midrangey sound).
Later in the week I"ll try another comparison.
The PR-D5 had the edge in readability when both KCVR Lodi (California, Deportes) and XERF (Mexico, norteno oldies) faded down and back up, implying that it has slightly better sensitivity... but whether it was the raw sensitivity of the PR-D5 or its voicing, I don't know (the SRII has fairly wide fidelity compared to the PR-D5's more midrangey sound).
Later in the week I"ll try another comparison.
Last night I did another quick comparison, same 1570 frequency. PR-D5 had the edge over the SRII, and the SRIII was roughly equal. WAs hard to tell which radio had more performance because of the different sound. As for raw sensitivity, they were basically equal, the PR-D5 maybe having a bit of an edge at times, maybe because of the tighter selectivity made for more readability when signals were down near the mud. Obviously, at least on the higher frequencies, my SRIII is a bit better than my SRII.
1570 is good for checking radio sensitivity in SE Michigan also. WWCK is 1 kW nondirectional with 282 mV/m inverse field, about 45 miles away across a bad patch of real conductivity, less than M-3. When I had a borrowed FI meter, I measured about 125 uV/m Day in the Winter and about 50 uV/m in the Summer. When I picked out the Panasonic RF-2200 from Service Merchandise, that was he basis on which I purchased the radio. The GE SR II also receives WWCK, but not as good as the RF-2200.
I recently bought a Tecsun PL390, and although it can receive WWCK, the DSP seems to be what determines its effective sensitivity. I want to try it with my small loop soon.
WWCK, being nondirectional, seems to be well maintained, and obviously doesn't have a lot of the directional maintenance problems and STAs that other stations seem to have, so the signal is pretty dependable. They used a 1947 model transmitter for a long time with 807s for IPAs, and those kept going bad. I don't know if they have a new transmitter now or not.
I recently bought a Tecsun PL390, and although it can receive WWCK, the DSP seems to be what determines its effective sensitivity. I want to try it with my small loop soon.
WWCK, being nondirectional, seems to be well maintained, and obviously doesn't have a lot of the directional maintenance problems and STAs that other stations seem to have, so the signal is pretty dependable. They used a 1947 model transmitter for a long time with 807s for IPAs, and those kept going bad. I don't know if they have a new transmitter now or not.
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Well up here in the NW US 1570 is similar to some of the X-Band frequencies (namely 1650 and 1690), there really isn't much to hear except DX: there's XERF, and the religious station in Missouri, and KCVR in California which doesn't always come in for some reason. I"ve heard snippets of other stations but usually very brief. Crainbebo (in Yakima, on the other side of the Cascades) has heard more stations on 1570 I think.
But it's a decent test frequency for DX radios, because the dominant station (XERF) doesn't always come in well, so you have a great DX station to use as a test for radios.
But it's a decent test frequency for DX radios, because the dominant station (XERF) doesn't always come in well, so you have a great DX station to use as a test for radios.
I just looked at the 1960 NAB Handbook for the groundwave graphs. I also roughly calculated the distance from the section line grid, and the distance to the 1570 came out to about 42 miles. The Winter whole path corresponds to 5 mS/m and the Summer whole path to 2 mS/m. M-3 is 8 mS/m over the whole path. The TL site is probably close to 8 mS/m, and within a few miles of my receive location is close to 8 mS/m where the soil observably turns to clay from sandy. In between in Summer, I would guess that parts of NW Oakland County are in the 0.1-1 mS/m based on soil type and radial conductivity measurements shown on CDBS applications on similar soil within 30 miles of Gaylord, MI.
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