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Author Topic: 630 meters  (Read 41671 times)
K4EJQ
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Posts: 101




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« Reply #45 on: December 27, 2012, 10:38:32 AM »

Hello All; Just when you thought you were rid of me, up I pop!!! It's been over a month since I last saw a post here and was wondering if anyone has heard a "Start" date for use of this band? I'm hearing additional experimental licenses coming on the band about every time I do a band search. But as of today, I have NO idea when "normal" amateur radio communications may begin. I understand the ARRL has filed a petition with the FCC for same. Anyone out there with update??? Thanks. Bunky ( in the basement )
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K0OD
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Posts: 2558




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« Reply #46 on: December 28, 2012, 06:03:34 AM »

The model for 600 meter approval would have to be the expansion of the 60 meter band last March to include new modes and 100 watts. That also required lengthy approval from the NTIA and the FCC. Final approval was announced 90 days before the start date, as I recall.

So we're not even at that point on fully opening a 600 meter band in the U.S.. The best source for such specific info may be the 600 Meter Research Group and its very active email reflector. I believe that's where the experimentally licensed transmitting stations hang out:

http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
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G3RZP
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« Reply #47 on: December 29, 2012, 01:31:04 AM »

Available in the UK after you have obtained a licence 'Notice of Variation' from Jan 1, 2013.
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K0OD
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« Reply #48 on: December 29, 2012, 08:02:25 AM »

New Zealand is really getting behind the band with their new allocation. No bandwidth restriction?  As in voice? 25W eirp. Gonna need some big tubes down there.

"Frequency range:  472 kHz to 479 kHz
> . Type of allocation: Secondary (see definition below)
> . Power Output:  25 W eirp
> . Bandwidth restrictions:  None (the previous 200 Hz limit is removed)"
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G3RZP
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Posts: 4713




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« Reply #49 on: December 29, 2012, 10:09:20 AM »

Now if you could only persuade the White House that releasing that band to amateurs would pump $1000 billion into the US economy in 2013 and have unemployment  drop to 0.1%, it would happen overnight!

But as that can't be done, it must well down the FCC priority list.....
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K4EJQ
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Posts: 101




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« Reply #50 on: January 02, 2013, 09:23:35 PM »

Hello Group: Yeah, I'm not going to hold my breath waiting for the FCC to move on this. I am planning to begin a "second generation " transmitter/ transverter project to keep idle hands busy during these cold and miserable winter days when I can't play outside with the other kids my age. Also giving some thought to an improved aerial ( higher-vertically). An additional RF amplifier for 475 Khz utilizing an existing 3-1000 job I built years ago for 160 through 10 meters may be another winter project-use what ya' got.
"Too much time-not enough money" a common problem for us "Roll your owners". Happy New Year All. 73, Bunky ( In the basement)
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GW3OQK
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Posts: 153




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« Reply #51 on: January 28, 2013, 01:30:04 AM »

Hello Bunky
I made a variometer using plastic 125mm extactor-fan tube and now can tune up my 160m inv L on 630 metres. 4700 pf in parallel with the coax feed. I get 1.6A aerial current which is what I reckoned was needed for 5w eirp. The TX outputs no more than 35 watts and is the WW2 T1154, picture on my QRZ. So, I dont reckon 100s of watts are needed if you have a decent 160m ant.

Hoping to get some qsos soon and I am starting on my own solid state TX for the modern shack.

73
Andrew (in the annexe)
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K4EJQ
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Posts: 101




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« Reply #52 on: January 28, 2013, 12:55:24 PM »

Hi Andy ( in the annexe); I now have a large variometer myself courtesy of my neighbor ham who is also chomping at the bit to get going on 630 meters. He built it up to handle large power levels so it is substantial in size but can house it in a 5 gallon plastic bucket.

So far , I have collected up the large vacuum variable for the plate tuning capacitor and wound the new PA tank coil on a 3 inch diameter form which measures 145 uhy. It uses Nr. 12 silver plated wire with Teflon insulation. A number of 1000 pf /12 KV ceramic capacitors have been obtained along with winding a 10 long-1 inch diameter RF choke ( 2 Mhy) for the tank circuit. I am building the new heavy duty plate bandswitch at this time-the parts for which probably flew over Europe during WW2. A more peaceful mission this time!!! Hi. I'll let you know the outcome of this end of the project as it progresses.

73 de Bunky ( in the basement)
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K4EJQ
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Posts: 101




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« Reply #53 on: February 18, 2013, 07:45:03 PM »

Hello Andy in the annexe; I thought I'd bring you up to speed on my latest project--revamping one of my 3-1000Z amps that works 160-10 meters to include  the 630 meter band. I got help from a friend after the ARRL DX CW test ended and we manhandled "the beast" from the operating room to the work area . This thing weighs over 125 pounds and requires 2to lift. I'll replace the 250 pf r variable (pl. Tuning) with a 500 pf vacuum variable. The new cap has X3 the working voltage. All the air-Dux coils will be replaced with a new homebrewed 4 inch diameter Silver plated No.12 wire wound coil with 170 uhy avlible inductance with multiple taps throughout it's length. A new RF plate choke of 2 Mhy will replace the 470 uhy unit in place. Additional by-pass capacitors will be added to the HV Line. A heftier plate blocking capacitor will also be incorporated along with more hefty capacitors in the RF Output tuning. I'll keep you abreast of how the work is coming. 73, Bunky in the basement
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WA9CFK
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Posts: 96




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« Reply #54 on: February 19, 2013, 07:16:29 AM »

The 630 meter band has tweaked my curiosity. The biggest question I have is what type of antenna?

In my case, 500 feet of wire strung down the tree line would be doable, but in terms of height/wavelength it may as well be on the ground.

It is the same for a 45 foot vertical. It is so short compared to the wavelength it must be horribly inefficient, not to mention that unless you live in a salt marsh you need to bury a miles of radial wires.

All that said, I have had reasonable results with a hundred watts and an 80 meter Hustler mobile whip while cursing the Interstate. It certainly was not the model of efficiency either.

At any rate, we are Hams so we have to give it a try. It will be fun seeing what others come up with.
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K4EJQ
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Posts: 101




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« Reply #55 on: February 19, 2013, 11:24:32 AM »

Hello Ron; Well, yes, the aerial can be a somewhat daunting challenge for most of us hams. But as you apply pointed out," we're hams and that's what we do". It's a problem for the majority of us but not insurmountable. Until someone figure out how to overcome the laws of physics, it will be a universal challenge for the majority of hams. That aside, along with the lamenting of the lack of salt water marshes with magnificent tall radiators arising, lets take a look at what is achieveable on a reasonable budget in your average backyard.

The aerial here, as mentioned in previous posts , is a simple inverted L which I use with a homebrewed remotely controlled antenna tuning unit which allows operation on 160 through 10 meters. To this I added, between the tuner's output and the base of the antenna, a tapped 750 uhy inductor. This allows operation ,with a very low SWR, across the 472-479 KC band as well as coverage of the NDB frequencies down through 300 KC or so as well as the Lower end of the AM BCST band. This additional tuning coil along with a future -use variometer are housed in some tough 5 Gallon plastic buckets external of the original metal encased HF tuner unit. This "add-on" tuner is switched in/out remotely as needed to work 630 meters.

The radiating element measures 60 foot high and approx. 105 foot horizontal. It is supported by two trees 140 feet apart. It is constructed of N0. 12 stranded / insulated TW (electrical wire). The antenna itself measures app ox. 35 ohms resistance  @ 475 KCS using my old General Radio RF Bridge. I have a large radial system ( mostly buried ) under this antenna along with a second "L" of equal dimensions that runs perpendicular to the original at the same height that can be switched in or out to take advantage of any directivity.

This antenna system was not born overnight. It began 17 years ago as a "simple" L" for 160 meters only. Like Topsy, it began to grow and still is. Hardly a fall goes by that I don't add more radials and additional grounding in the system. I tell myself it's for lightning protection...I tell myself lots of things...

Have fun-It's HAM RADIO.

73, Bunky, K4EJQ
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K4EJQ
Member

Posts: 101




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« Reply #56 on: March 13, 2013, 08:08:51 PM »

Hi Andrew. Send me your e-mail address ( Directly ) and I will send you the pictures of the 630-10 meter RF amp. ( 1 KW )I built this winter to kill time. Bunky  K4EJQ , in the basement
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GW3OQK
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Posts: 153




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« Reply #57 on: March 14, 2013, 02:23:09 AM »

Hello Bunky
af-aditel@btinternet.com or click link on my qrz page.

I have had my T1154 in operation and made a few CW QSOs. The slight chirp and drift give it a wonderful sound I think. There isnt much CW activity and I have found I can hear some DL and HB9 but they never hear me answer. There is sometimes very deep qsb at night and in a few seconds the signal is gone from say S3 to S0. All very interesting

73
Andrew (in the annexe)
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KH2BR
Member

Posts: 103




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« Reply #58 on: March 14, 2013, 10:14:17 AM »

I have been amazed at how well a magnetic loop works on 40 meters. I don't have one but have had a few cw contacts with guys using them. I wonder if a magnetic loop would work way down there? If it is doable, then I think I might go for one of the JUMA rigs.
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K4EJQ
Member

Posts: 101




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« Reply #59 on: March 15, 2013, 10:04:54 PM »

Andy et al; Fired up the rebuilt 3-1000Z amp tonight for the first time on 630 meter band into a 50 ohm dummy load. I had used an RF bridge to "preset" the band taps on the new larger tank coil, so I knew pretty much "the beast" would hit 630 meters.

With about 1000 pf of plate tuning capacitance, 138 uhy plate inductance and 8000 pf output tuning capacitance-2000 pf of capacitance in the plate blocking capacitor along with a homebrewed 1.9 Mhy RF plate choke , the amplifier tuned beautifully. With 2500 volts DC on the anode @ 320 ma. plate current, 125 ma. of grid current -about 28 to 35 watts drive level, the amplifier delivered 500 watts of power. No "drifting" of parameters noted-no heating of tank components. Figures indicate 60% plate efficiency-3.2 amps RF current into 50 ohms load.

I have not had time to conduct tests on the other bands with this amp. but initially the thing indicated it will tune well above 30 Mhz in coverage using the RF bridge. Multiple heavy duty switched are used to limit the values of plate tuning, bandswitching and coupling to limit the tuning range so as to reduce risk of harmonics.

I will do further tests using the spectrum analyzer later as I can find the room on my overly crowded work bench. The photos I sent were made before any tests were conducted-less you see charred components, Hi. I have not, to this date, "pushed" the amp. as I don't have a spare tube for it. When  this one goes I will convert "the beast" to a Russian GS-35b. I guess that is one of the problem the homebrewer faced- so little time/money but so many options, HI. 73, Bunky, K4EJQ ( In the annexe )
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