Noise? active antenna for 200 Kc to 200 MHz

Since i'm mostly active on 160 or low bands and live on the edge of the town, the 77 feet high inverted L with 3000+ feet of radials doesn't make it difficult to put out a decent signal on 160 - 20 meter with the MFJ 998 autotuner fed at the bottom of the L.

Most of us not blessed with a shack in the woods far from civilisation, and have the problem to recieve, and no place to put up beverages or even a K9AY loop.

I made a amplified magnetic loop with a long tailed pair of BFW16A ( 1.1 GHz Ft ) transisters, and found the next building project to get even less noise and more usable signal.

http://pa0fri.home.xs4all.nl/Ant/Act...enna%20eng.htm

Description there, including schematic diagram, the ina 02186 MMIC can be had on the internutz cheap.
Rest is junkbox material, for the loop you can also use a 13 feet section of RG 213 if coppertube is too expensive.

Í oredered 10 of the MMIC's if they arrive the next building project is on the table.

Nobody interested?

hmmm, maybe i better trot back to the politics section ;)

I could bitch about you posting this, but I thought it was a good link, with a decent project :)

Waiting for the MMIC's to arrive from my supplier, till them making the pcb, get the parts from the junkue box ;)
Remembered i'm a ham as well, soldering iron(s) were cold too long.

Some years ago I made a couple of preamps with those bad boys. Two in cascade was WAY too much gain for 2M weak signal work, one was quite enough.

Your garden loop rather does stand out... like a tree in a forest.

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Originally Posted by PA5COR

Nobody interested?

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Easy now, calm yeself. I (and many others) may not have seen this yet. I'm interested because I'm setting up a SDR and need a good low-noise active system. I'll check it out.

Very good. I just read and listened to the MP3s. I built one of these years ago for my summertime 160m activity and it was fabulous, although mine was not an active antenna and I used CATV cable from the cable company (75 ohm hardline).

I have a recording somewhere that I'll post for you to hear the difference. I switched from a full-size 160m dipole to the RX loop in the recording and it is scary how great that thing cleaned up the noise.

So, I think I'll build up the same system that I had before except I'll add that amp design. Veddy nice. Thanks.

Cheers, always pleasing to b able to help.
Running a amplifid loop now of own design, i just wanted to try this one out.
Have several pieces coax left 15 millimeter thick ( Ecoflex 15) that i can use for the loop.

For 2/70 i used the MGF 1300 series GaAs fets as pre amps, well build you got an incredible low noise and good gain.
If i turned my beams towards the sun i could hear the noise come up.

I just snatched up 5 INA01286's on eBay for $7 shipped.

I got 10 from Israel ( of all places) for 10 dollars, 4 bucks to send them over, waiting to see them arrive....

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Originally Posted by PA5COR

I got 10 from Israel ( of all places) for 10 dollars, 4 bucks to send them over, waiting to see them arrive....

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Nice! I'm gonna start on the loop after work today. Here's the file I mentioned earlier. The first three seconds is on a full-size 160m dipole, the last three are on the RX loop. It's a short clip, but you can hear the noise vaporize. This was recorded in the afternoon and in Summer and my buddy (WA4GEG) is about 130 miles from me.

http://168.8.96.100/~pheaton/wa4geg.mp3

That is indeed a remarkable difference.


My current homebrew amplified loop can do the same under difficult circumstances, but not always.
Other parts are collected, will cut out the pcb tomorrow and put the other parts already on it, till the MMIC arrives.
Loop from the coax will be made in the weekend.

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Originally Posted by PA5COR

I got 10 from Israel ( of all places)

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I tried one of those in a AM BCB radio I built. It worked okay until I tried to listen to KPIG in Santa Cruz (California). It just wouldn't let me tune in for some reason.

The MMIC data sheet has some good tips on the build plus a board layout if you want to etch it.

http://www.datasheetcatalog.com/data...NA-02186.shtml

As usual the first thing read about the MMIC, building if in H.F. type building wise is mandatory.
Short connections, good grounding of both planes etc...;)

I received the MMICs on Saturday. Now to get to etching. One thing on the schematic, the "15" cap on the output of the MMIC box. I'm gonna assume that's a mistake on the drawing?

Or is it meant to be 15pF?

15 PF it is, meant to keep very high frequency oscillations away, has no effect on the HF amplification, just stabilising the MMIC.

You will find that 15 PF back in the decoupling of the + rail before the 470 micro Henry inductor.
Planning to replace that by a torroid and teflon coax wound around it for decoupling as further up at the bottom of the article is described.
In stead of the torroid you can also use a small section of a ferrite bar.

Cool; yep anything that wide (BW wise) will need anything above HF shorted to ground. I've drilled my board and am now administering the finger polish (yep, I"m high tech - haha).

RFC1: Mantelstroom filter, ringkern 4C4, 14mmØ, 9 windingen

http://pa0fri.home.xs4all.nl/Ant/Act...enna/rfc-s.gif

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Originally Posted by N4BBQ

I received the MMICs on Saturday. Now to get to etching. One thing on the schematic, the "15" cap on the output of the MMIC box. I'm gonna assume that's a mistake on the drawing?

Or is it meant to be 15pF?

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How do you make your boards?

Ina MMIC (10) just arrived, let the fun begin ;)

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Originally Posted by K7SGJ

How do you make your boards?

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Back when, I worked for a defense contractor. They would test their conformal coat process on double-sided 3x6 copper boards, then they would toss them into the trash.

I have a lot of 3x6 copper boards! haha

Most of these projects are done the "manhattan" way, unetched copper boards which i buy in bulk of different sizes, thickness single/double copper coated and small islands made for the parts that need to be connected, rest is mass or -.
Small rail etched for the + done.

Larger and projects that need a pcb done for me at the ham club, they hav all the stuff there, no need to play around with etching fluid here and get stuff ruined ( Don't ask) ;)

The pieces of unetched pcb are also nice to make project boxes, using ,my 100 watt soldering iron to solder them together easily workable on and keeping the plain side without copper to the outside a can of acrylic automotive paint does the rest.

Here's a pic of one before I use it. The board in the holder is the one for this project. The one in the foreground is an HV supply board for a tube-type audio amp I'm building my step-son.

http://168.8.96.100/~pheaton/boards.JPG

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Originally Posted by PA5COR

no need to play around with etching fluid here and get stuff ruined ( Don't ask) ;)

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Hmm, please elaborate.

I am yet (fingers crossed) to destroy anything (other than the copper board).

As i wrote, don't ask, ruined a perfect whitewashed wall spilling the stuff, clothes ( falling apart a week after the ferrichloride had it's way) and a now ex wife upset like hell.
Took some good work to get that wall white again...;) meh......sh*t happens.
Dang little creeps those ina 02186 thingamabobs.... don't sneeze with one unsoldered on the pcb... ( also don't ask, found it back though...)

As i wrote, don't ask, ruined a perfect whitewashed wall spilling the stuff, clothes ( falling apart a week after the ferrichloride had it's way) and a now ex wife upset like hell.[/quote]

Goodness; it's a wonder I've not destroyed some wood flooring or carpet yet myself.

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Originally Posted by PA5COR

Dang little creeps those ina 02186 thingamabobs.... don't sneeze with one unsoldered on the pcb... ( also don't ask, found it back though...)

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Now that kind of stuff, I have done numerous times. The worst thing is iPhone screws when I'm replacing displays on those dreadful things. I've lost a many of them.

I started dabbling in electronics at the ripe age of 12 years old, tubes big large components and 20/20 vision, now I'm 61 and fall back to itty nitty smd stuff, thought it should be the other way around.....;)
Steady hand, standard soldering iron i did lots of work with smd though, building Ga-As fet amps for 2/70/23, lots of modding the FT 847, and some work on the FT 100, including adding the AM filter.
I liked the rebuild of the Heathkit SB-1000 more ;)

Will make picccie later of the "enourmous" amplifier board.... postage stamp size...

Build the print added the teflon and ferrite stuff.

Attachment 11745Attachment 11746

I'm a sh&t photgrapher, but you get the idea.
Pcb has been drilled through at 10 places and a wire is now connecting upper and lower copperlayers.

B.t.w. i found that nail polish (looking at that bottle in your piccies) is a good preserver of outdoor prints, just get the stuff all over it let it dry and no moist will get to the components or pcb.
Larger pcb's i spray just like my alu antenna's with clear coat tectyl ment for protecting chrome ( bumpers) in winter.
Colorless just like lacquer but much more resilliant outside.

http://pa0fri.home.xs4all.nl/Ant/Act...enna%20eng.htm

It's a beautiful circle, I have springs and an anvil bending device but couldn't emulate that. Would a square of the same circumference be a good substitute?

What I've done already for lightweight VHF/UHF arrays is make them from fibreglass rod and fix self-adhesive copper tape round the rods. A llittle soldering with strips of real copper to join them and a copious quantity quantity of varnish and it's done.

How about 15mm polythene pipe in a circle with the aforementioned copper tape wrapped round? It's readily available retail here, sold as slug and snail deterrent for garden flowerpots.

Square will work just as well.
The copper pipe used here in that article is copper pipe on a roll 6 mters very soft copper pipe to install in homes because it is soft it is easy to bend.
I just use Ecoflex 15 coaxial cable i had left over 15 mm outside diametre and large core.
All my boxing projects are pcb one or 2 sides copper, easy to work on with plate scissors, or hacksaw, easy to solder using a 100 watt iron, easyy to work on making holes in it, and a coat of paint will do the job.
Loop is made, i changed the schematic to incorporate the a 78L06 on the pcb, feeding the amplifier with my 14 volt supply that feeds the loop i have now with homebrew amp, just the incorporated 78L06 now lowers the voltage on the INA to measured 5,5 volts as it was in the specifications of the amplifier.
That means a drop of 0.5 volts over the 33 Ohm resistor, or 15.15 mA running through the amp.
That is 83 milliwatts dissipation out of 400, a safe setting, leaving enough headspace.
Depending the weather i will change the loop this weekend and see what results it brings.

I plan to make another loop with the same idea as the current loop, 4 meters alu strip as antenna, and a dual ina 02186 amplifier each one amplifying one end of the loop as i do now with the BFW 16A transistors in long tailed pair diagram.
That one already gives good results now.

Enough to experiment ;)