[Lowfer] Beacon "IO" QSY to 185299.2

Mon Feb 8 15:49:53 EST 2010

I do not have my info with me so I'll be going from memory.

I saw Lyle's pages - I think when I last read them I didn't have enough 
hands-on to fully appreciate them.  I'll go over them again now that I have 
a better idea of what I'm doing.

The coil is 6" diamater with a total of about 175 turns.  I now believe this 
is too many, but we'll see.  I have 10 or so taps and I'm finding that I'm 
only needing about 100 turns to get what my old thermocouple RF ammeter says 
is close to resonance.  I have 3 such ammeters, but two are 3A FS and one is 
.025A FS.  I'm almost maxing out the smaller meter and get no hint of 
current on the bigger ones.  I may look at building another meter, or do the 
string of NE2s thing.  I'm discovering the first step should be building 
tools to help you tune everything.

My coil is wound with #22 enameled for the bottom 75 or so turns, with the 
rest I think #24.  No 5-gallon drums wound with co-ax yet.  I have taps at 
2, 4, 8, 16, 32, 75, 100, 150 and 175 turns.  The unused higher taps are a 
great source of RF burns even at 1 watt.

I'm trying to keep this simple, so would prefer to keep the transmitter 
output stage intact and do all the work on the loading coil side.  I plan to 
move this to a wooded area of a property we own about 20 miles from home 
once I get things working well, and like the compact nature of the LF-90. 
I'll eventually be running it off of a solar panel I have.  The doc from the 
LF-90 says it's designed to have 1 watt maximum at 13.8 volts, and from what 
I can tell that's about right.  The final goes directly off the DC source, 
which is a 12V lead acid battery I charge with a solar panel.  I can provide 
more details on the output schematic next weekend.  But the output circuit 
off the final FET seems to be a Pi design, and I think it's expecting a 50 
ohm load.  From the final it has a series cap to block DC, a cap to ground, 
a toroidal coil (66 or 88 mh?) another cap to ground.  I think it has a 2nd 
coil and a 3rd cap.  It's designed to work from 130 to 200 KHz with no 
transmitter tuning, so the output stage is more of a wideband low pass 
filter.  Nothing on the LF-90 is adjustable except the crystal cap to 
fine-tune the frequency of the synthesizer, and a pot for the CW speed. 
There is a jumper - I think in the driver - to adjust for use at 137KHz. 
That's it for adjustments.

I also have an older model transmitter from them, and may look at using that 
one if I end up playing with the final stage.  I think it has a more 
traditional tuned output circuit.

Because my location is heavily wooded, and the HOA prohibits antennas I have 
to hide the antenna in the trees.  From what I'm reading I might be better 
off scrapping the vertical (really more of a horizontal since the vertical 
piece goes only 12' up our deck, and the top hat goes down the slope into 
the trees)  and going with a 50x50 loop.  It seems that in wooded locations 
the loop may get out better.  My ground system is marginal at best.  Just a 
couple of ground rods and so far no ground radials.  Hey - this is a first 
crack at this.  The loop would solve a lot of problems if I can properly 
match it.   But that project will need to wait until the 3 feet of snow on 
the ground melts.

So I figure I lose -10db from the mismatch, -10db for the poor ground, -10db 
for the compromise vertical design, and -10db absorbed by the trees. 
Probably no wonder nobody hears me yet.

Craig

----- Original Message ----- 
From: "Charlie , W5COV" <cvest at cox.net>
To: "Discussion of the Lowfer (US, European, &amp;UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Monday, February 08, 2010 2:40 PM
Subject: Re: [Lowfer] Beacon "IO" QSY to 185299.2

> Craig , tell us more about your antenna and loading coil . Wire size and 
> type , coil diameter , number of turns , where it is tapped etc .
>
> If you haven't visited Lyle's old pages , there is a lot of good 
> information on them .
> http://www.nutstreet.net/k0lr/
>
> Thanks to Eric for preserving them .
>
> You could always add a K0LR final stage and if your antenna is less than 
> 50 ohms he even has a chart in one of the articles for winding it for 
> lower resistance antennas .
>
> I find his "Clamp-On-RF Current Probe" to be virtually a necessity , to 
> see what differences you make with any change .
>
> Like Jay said , a variable voltage supply for the finals is also a must . 
> What kind of voltage and current do you show ? I am not familiar with that 
> particular transmitters output stage , I have an older model of it . If 
> you could sketch out the final section with transistor and parts values 
> used , that could help also . Can't have too much information , so this 
> fine group can help you get a successful beacon on the air .
>
> I think it is fine to keep it on list . There are people here with years 
> of experience and a great wealth of knowledge .
>
> If you have pictures and would like to post them and they are larger than 
> the list will accept , please feel free to post them on the Yahoo part15 
> Group . (There is no space between the part and 15 ).
>
> Many of us are on that list too , along with more people that are a wealth 
> of information and parts . It doesn't compete with this list , just tries 
> to compliment it , by posting pictures and helping newbie's .
>
> Always glad to help if I can .
>
> Charlie , W5COV
>
> CV , 185.298.5 kHz. , QRSS60 , 24/7 , EM26ex , OK.
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