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Author Topic: 630 Meter Reception - Start Cheap and Simple  (Read 2044 times)
K0OD
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« on: October 28, 2017, 09:21:56 AM »

Over the years I've noticed that my simple DX Engineering 43' vertical seems to pick up longwave stations decently. I've been able to hear European AM broadcasters in the 160-220 KHz range late at night and especially during the deep wintertime. I get plenty of NDBs. But how does it compare with larger, costlier and more complex antennas? I had no way to know... until now.

For the past few nights I've left WSPR running in the receive mode on 474.2 kHz from sunset to sunrise. It's fun to wake in the morning and scan the night's catches which have been extraordinary even though the best DX season is probably a month or two off. 

I've noticed that I can compare my overnight receptions with those of others on wsprnet.org. Presumably some listeners are much better equipped as they can also transmit on the band. Many are longwave "old timers" from the ranks of the experimentally licensed with fields of quiet rural acreage devoted to longwave.

A 43' vertical is simply a big aluminum stick that's probably no better for listening than a hunk of random wire. My antenna uses a basic radial system and I'm on a very typical suburban acre lot surrounded by other homes with the usual noise sources. Still I can tell from WSPRNet that my setup hears 474 kHz signals as well as most listeners in the Midwest.

Don't think you'll need a 1,000 foot beverage or one of those faddish loops. You don't even have to tackle a new digital mode like WSPR. There's a fair amount of two-way CW on 630 meters. Try listening to the new bands with what you have already. You'll surely be amazed.
 
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AA2UK
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« Reply #1 on: October 28, 2017, 11:56:27 AM »

Most stations that can transmit on MF use a separate RX antenna, they are often small 6-8 verticals with an LNA called E probes.
There are also small rotatable RX loop antennas that also use LNA's.
I'd suggest using your DX Eng 43' vertical with a base coil and Variometer as a TX antenna.

I actually use my PAR 6 meter Moxon with my IC7410's internal LNA for now.
Compared to some locals I RX about 5 dB better using WSPR, go figure? I assume the Moxon acts like a small horizontal loop at 630 meters.
I suggest trying anything for 630 meter reception, you might be surprised what works and what doesn't.....
73, AA2UK
Bill
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K0OD
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« Reply #2 on: October 28, 2017, 12:33:21 PM »

Quote
"I'd suggest using your DX Eng 43' vertical with a base coil and Variometer as a TX antenna."

I'm looking at ideas like that. A stock 43' vertical transmits terribly even on 160 meters. Simply adding a base loading coil improves the transmitted signal by 10 dB. Top loading helps even more. I'm worried about the presence of high voltage on longwave matching networks.

Quote
"Compared to some locals I RX about 5 dB better using WSPR, go figure?"

Where I live, in eastern Missouri, it's hard to do perfect comparisons. Longwave WSPR activity is sparse. Comparable receiving stations are generally two hundred miles away but vastly more activity than in the past. There's no one transmitting on 630 in Missouri.

It would be nice to know what everyone uses on the band, a database of active 630-M WSPR stations.
« Last Edit: October 28, 2017, 12:35:29 PM by K0OD » Logged
AA2UK
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« Reply #3 on: October 28, 2017, 12:48:35 PM »

Not sure if you are aware of this site but it lists stations and activity on a daily basis. There are also lots of good links about LF/MF projects and ideas.
http://njdtechnologies.net/category/630-meter-daily-reports/
Bill, AA2UK
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K0OD
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« Reply #4 on: October 28, 2017, 02:04:15 PM »

Yes, I know about that excellent website. Where would your variometer come from?

The noise level on my receiver rises about 8-12 dB even on a quiet band when I attach the DXE vertical. So no preamp is required.

You're in NJ (right?). Have you printed any Europeans yet on 630? My experience is that longwave conditions peak in December and especially January.
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AA2UK
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« Reply #5 on: October 28, 2017, 03:20:32 PM »

I'll be building my base load coil and Variometer. I'm still not sure if I want to use a vertical or a basic Marconi T
My goal is to be on the air by New Years Eve.
I have just started listening to MF so no Europeans yet. I have decoded DM33 a station in Arizona not nightly but often.
I copied 6 stations on CW and a few using FT9 the last 2 nights.
73
Bill, AA2UK
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G8YMW
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« Reply #6 on: October 28, 2017, 04:23:22 PM »

I would suggest putting a wire across the top of the vertical to make a Marconi T.
Make a fair Topband transmit aerial and put a base coil in when you want low MF or LF.
Something like a plastic dustbin or laundry basket (similar size) for a former.
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73 de Tony
Windows 10:  Making me profane since March 2017
K0OD
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Posts: 2952




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« Reply #7 on: October 28, 2017, 07:49:04 PM »

Bill, you need to duplicate whatever AA1A uses up in the Boston area. His signal is reliable every night at my QTH, a distance of 1059 miles, and I know he often makes it well into Europe. As I type this, WSPRnet shows AA1A being copied in Southern California!

My goal is to print something from Europe which should be possible. I copy K9FD/KH6 almost every night from 4066 miles away. London is about the same distance.
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KM1H
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« Reply #8 on: October 29, 2017, 05:18:55 PM »

With the experimental license many used Ive been heard in Sweden and California with 5W CW a few years ago.

Carl
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AE5X
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« Reply #9 on: October 30, 2017, 05:47:36 PM »

I just made my first WSPR transmission on 630 meters and am absolutely amazed at the results with such a simple and cheap set-up. I waited until another Texas station started his evening receive session thinking no one further away could possibly hear what I have as a transmitting station.

Nine stations heard that inaugural transmission including one in the Cayman Islands.  Cheesy

I'll post full details on the set-up on my blog tomorrow but it was dirt-cheap to get on this band with what's turned out to be a decent signal - again, much to my surprise.
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KD8IIC
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« Reply #10 on: October 30, 2017, 07:57:38 PM »

Best RX antenna by far I have found is an active loop low to the ground for hearing NDB and the ARRL experimental stations. Those ARRL experimental low power stations were paving the way for this new band's use the past few yrs.
There are a few of these loops on the market. Mine is a Pixel built. MFJ is making some low cost ones too and of course on can be made using coax cable and a real good low noise pre-amp at its' base. Low to gnd is best.
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K0OD
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Posts: 2952




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« Reply #11 on: October 31, 2017, 03:35:56 AM »

I just made my first WSPR transmission on 630 meters and am absolutely amazed at the results with such a simple and cheap set-up. I waited until another Texas station started his evening receive session thinking no one further away could possibly hear what I have as a transmitting station.

Nine stations heard that inaugural transmission including one in the Cayman Islands.  Cheesy

I'll post full details on the set-up on my blog tomorrow but it was dirt-cheap to get on this band with what's turned out to be a decent signal - again, much to my surprise.

Can't wait to learn what you're using.

Here's who's hearing AE5X right now (around 1030z)
Heard by: AH6EZ, CF7MM, K0OD, K1UTI, K2BLA, K4LY, K5DNL, K5DOG/5, KR6LA, KR7O, KU4XR, N1DAY, N1VF, N2EJT, N2NOM, N4DB, N5CEY, N5KS, N6LF, NV0O, SWL/K9, SWL/W4, VE3CIQ, VE6JY, VE6XH, VE7BDQ, VE7CNF, W0JW, W1XP, W3PM, W3SZ, W5EST, W6SFH, W7IUV/W, W8RUT, W9XT, WA3ETD, WA3TTS, ZF1EJ
« Last Edit: October 31, 2017, 03:42:06 AM by K0OD » Logged
K0OD
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Posts: 2952




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« Reply #12 on: October 31, 2017, 06:43:25 AM »

Best RX antenna by far I have found is an active loop low to the ground for hearing NDB and the ARRL experimental stations. Those ARRL experimental low power stations were paving the way for this new band's use the past few yrs.
There are a few of these loops on the market. Mine is a Pixel built. MFJ is making some low cost ones too and of course on can be made using coax cable and a real good low noise pre-amp at its' base. Low to gnd is best.

If loops are so great why do few 160 meter DXers and contesters use them? I've known savvy low band ops who discarded their loops after testing. As far as requiring a "real good low noise preamp," my simple 43' vertical generally picks up about 10 dB of atmospheric noise on 630 Meters. A random wire would probably produce about the same result. No need to amplify that. A small loop or the like MAY need some amplification. *May.* 

Loops can surely be valuable for notching out local ground wave noise sources when that's the problem. I doubt loops have value for improving the SN ratio of long haul signals. Atmospheric QRN is a signal. In any event, since we're mostly discussing WSPR, how about some putting some numbers with these claims. WSPR is made for testing antennas. 
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AA2UK
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Posts: 283




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« Reply #13 on: October 31, 2017, 07:51:05 AM »

I thought I'd add that many stations on 630 meters are using active E Probe antennas. They are usually placed anywhere from a few feet off the ground to 30'. I'm learning many of the RF principals we have learned about HF don't apply to LF/MF.
I've heard others having good results with small loops close to the ground.
What works at one location may not at others. I'm hoping to try an active NAVTEX antenna (as an E Probe) here soon and compare it to my current RX antenna.
73, Bill
AA2UK
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W9IQ
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Posts: 1705




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« Reply #14 on: October 31, 2017, 08:07:17 AM »

From the descriptions I have seen of "e-probe" antennas, they tend to simply be a shortened vertical with poor ground planes and usually a receiver preamplifier to make up for their poor gain.

The e-probe and h-probe concepts are generally totally misleading as they relate to antennas. Is there really anything new here?

Quote
I'm learning many of the RF principals we have learned about HF don't apply to LF/MF.

The principles are exactly the same. It is applying them correctly that may make a difference.

- Glenn W9IQ
« Last Edit: October 31, 2017, 08:10:17 AM by W9IQ » Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
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