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Author Topic: New here, and my journey building a SW xmtr  (Read 2540 times)

Offline Stretchyman

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Re: New here, and my journey building a SW xmtr
« Reply #15 on: September 23, 2018, 0746 UTC »
Dipole, approx 68' at 20' above ground.
This will give NVIS (Look this up!)

Daytime ONLY.

Nighttime will need way more power and a vertical.

Str.
'It's better to give than receive' so why RX when you can TX!

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Great discounts on ALL my transmitters if purchased via HFUnderground


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Offline ChrisSmolinski

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Re: New here, and my journey building a SW xmtr
« Reply #16 on: September 23, 2018, 1201 UTC »
cool you got it going .
there will be some who disagree with this.
i used a dipole as a inverted v just high enough to keep the ends off the ground about a foot .
and no earth ground .
1/2 watt carrier approx. was heard last night by ChrisSmolinski and it wasn't in his backyard by a long shot.
 no location will be provided so don't ask.
https://www.hfunderground.com/board/index.php/topic,46168.0.html

Thanks for the info on the power level, I enjoy the technical challenge of picking up lower power transmissions. Your signal was getting out great for half a watt. There were a few occasional peaks to SIO 333.  If you happen to have an eQSL for a 1/2 watt transmission... I have a recording. And thank you for the ID ;D
« Last Edit: September 23, 2018, 1209 UTC by ChrisSmolinski »
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
NRD 545 / netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 670 ft horizontal loop / 500 ft northeast beverage / 270 ft west-south-west beverage / 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop

Offline Channel Z

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Re: New here, and my journey building a SW xmtr
« Reply #17 on: September 23, 2018, 1348 UTC »
Welcome to the dark side.  All you need is a coax-fed, half-wave horizontal dipole cut for your operating frequency.  Mount it as high as you can.  No tuner required, and about as simple as you can get for good performance.  That's all I've ever used, and my results speak for themselves: 380 mW beacon received in France, 1.1 watt Corsette received 1,000 miles away, 16 watt LuLu received in Japan, 25 watt Commando regularly heard in New Zealand. 

Chris Smolinkski and I did some low power experiments, and you can hear for yourself the difference between 1.1, 14, and 25 watts: https://www.radiohobbyist.org/blog/?p=271

Also, if you want to try other proven transmitter designs, or need help with a build, please join the homebrewpirateradio Yahoo Group: https://groups.yahoo.com/group/homebrewpirateradio

Offline JimIO

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Re: New here, and my journey building a SW xmtr
« Reply #18 on: September 23, 2018, 1700 UTC »
"Says who?  ::)"

Says someone who can't find it on FM anymore! The best that's out there is 15 min. of tunes you heard thousands and thousands of times then 15 min. of commercials.
But now we have bittorrent and youtube-dl so we can rebuild our long lost vinyl collections.

Offline Josh

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Re: New here, and my journey building a SW xmtr
« Reply #19 on: September 23, 2018, 1942 UTC »
The whole reason for using shortwave is to use skywave propagation and to broadcast rock music mostly from the late 60's to early 70's.

Says who?  ::)

Only a philistine wouldn't consider this the heights of musical development;
https://www.youtube.com/watch?v=M0k0z2MtvLY
Conveniently located near Vincennes Indiana.

Offline skeezix

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Re: New here, and my journey building a SW xmtr
« Reply #20 on: September 23, 2018, 2124 UTC »
But now we have bittorrent and youtube-dl so we can rebuild our long lost vinyl collections.

Lost vinyl is not on the Internet. Gots to go to the record store.
Minneapolis, MN

Offline JimIO

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Re: New here, and my journey building a SW xmtr
« Reply #21 on: September 23, 2018, 2146 UTC »
I should have said "music collection of ...". Do you mean one of these?

https://en.wikipedia.org/wiki/Record_shop

Offline skeezix

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Re: New here, and my journey building a SW xmtr
« Reply #22 on: September 23, 2018, 2314 UTC »
I should have said "music collection of ...". Do you mean one of these?

https://en.wikipedia.org/wiki/Record_shop

Thar ye go. 'Tis exactly that.

If you want to make a backup of your vinyl, then record it to tape (something 1/4" or wider... the cassette tape will do in a pinch, but has something to be desired).


Minneapolis, MN

Offline fieldstrength1947

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Re: New here, and my journey building a SW xmtr
« Reply #23 on: September 24, 2018, 0518 UTC »
Thanks for the suggestions everyone -

Will reply in detail later but suffice it to say I'm testing at the moment with a quick and dirty half wave dipole, since I have room for it and I don't have the resources to put up an inverted V yet. I'll figure that out at some point. But in the meantime, this dipole gets my signal a fair ways out, by which I mean about 2 miles. Ha, some optimization will be in order.

Of course I do wonder what it's doing skywave wise.

Offline Stretchyman

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Re: New here, and my journey building a SW xmtr
« Reply #24 on: September 24, 2018, 0655 UTC »
2 miles is rather weird as you will NEVER get any 'Local' coverage so don't expect any!

Min skip distance is around 200-300 miles but will vary.

Hence the need for a bit of power as the signal has to go up a far way (30-150miles) to be diffracted by the ionosphere to come back down again.

Plenty of online SDR's to monitor your signal and good for comparing antennas too (you'll need to have both connected via a switch so you can flick between them)

Str.
'It's better to give than receive' so why RX when you can TX!

                            Buy one from me, NOW!

Great discounts on ALL my transmitters if purchased via HFUnderground


                                              ;)

Offline TheRelayStation

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Re: New here, and my journey building a SW xmtr
« Reply #25 on: September 24, 2018, 1138 UTC »
Thanks for the suggestions everyone -

Will reply in detail later but suffice it to say I'm testing at the moment with a quick and dirty half wave dipole, since I have room for it and I don't have the resources to put up an inverted V yet. I'll figure that out at some point. But in the meantime, this dipole gets my signal a fair ways out, by which I mean about 2 miles. Ha, some optimization will be in order.

Of course I do wonder what it's doing skywave wise.
what frequency and UTC times are you testing at so i can look out for you?
6880 Khz AM 20W Hack RF - shortwavepirate@aol.com

Offline TheRelayStation

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Re: New here, and my journey building a SW xmtr
« Reply #26 on: September 24, 2018, 1143 UTC »
All you need is a coax-fed, half-wave horizontal dipole cut for your operating frequency.  Mount it as high as you can.  No tuner required, and about as simple as you can get for good performance.
exactly this.
except that my horizontal dipole is full wave instead of half wave and its about 30-35 feet above the ground in the clear which is why i cant use 5150Khz, it was just too long and unstable.
after trying many different antenna/feedline designs and heights over the years, this works the best.
the downside is not being able to use other frequencies with 1.0 VSWR although VSWR isnt "everything".
6880 Khz AM 20W Hack RF - shortwavepirate@aol.com

Offline JimIO

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Re: New here, and my journey building a SW xmtr
« Reply #27 on: September 24, 2018, 1815 UTC »
I must be missing something. Please describe your antenna and feedline for me.

This website:

https://www.tutorialspoint.com/antenna_theory/antenna_theory_full_wave_dipole.htm

Says this:

Disadvantages

The following are the disadvantages of full-wave dipole antenna.

Heat dissipation

Wastage of power

No radiation pattern

No directivity and no gain

Due to these drawbacks, the full-wave dipole is seldom used.

Offline TheRelayStation

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Re: New here, and my journey building a SW xmtr
« Reply #28 on: September 24, 2018, 2126 UTC »
I must be missing something. Please describe your antenna and feedline for me.

This website:

https://www.tutorialspoint.com/antenna_theory/antenna_theory_full_wave_dipole.htm

Says this:

Disadvantages

The following are the disadvantages of full-wave dipole antenna.

Heat dissipation

Wastage of power

No radiation pattern

No directivity and no gain

Due to these drawbacks, the full-wave dipole is seldom used.
it appears from the drawing diagram, that they are including open wire feedline as part of the antenna.
i have coax fed right to the top of the dipole.
it did not operate as expected using full-wave with open wire feedline but worked perfectly with coax.
since im using a single frequency, coax will work in my situation.
i would tend to believe using highly shielded coax as feedline to the dipole is akin to bringing the TX right at the center fed part of the dipole.
« Last Edit: September 24, 2018, 2132 UTC by TheRelayStation »
6880 Khz AM 20W Hack RF - shortwavepirate@aol.com

Offline fieldstrength1947

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Re: New here, and my journey building a SW xmtr
« Reply #29 on: September 24, 2018, 2333 UTC »
Testing in a bit here on 6780 kc starting at about 0000 UTC.