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1
General Discussion / Re: PLEASE READ! Welcome to Ra...
Last post by PD1RWK - February 20, 2020, 03:13:58 pm
Hi Gil.
Just joined today and would like to say hello.
Still consider myself as a newby, eager to learn more about this hobby.
Preparing myself for my full licence and morse.
Enjoying your YouTube channel(and all the other channels ofcourse.)

73 Robert PD1RWK
2
Antennas / Re: EFHW observations and radi...
Last post by drdbt - February 16, 2020, 10:15:48 am
Hi Dylan, I'm new here but came because I know Gil uses EFHWs quite a lot and I'm interested in them as well.

It seems to me you had your antenna configured as a sloper. That's a good configuration based on my research (but not experience -- yet).

In working on this research problem, I found this model of the EFHW and thought I would share. The paper is at https://wv0h.blogspot.com/2019/10/end-fed-vertical-antenna-variations.html and it appears to be well executed and written.

I prefer to not rely on anecdotal results because they are so variable and dependent on propagation. It requires a sizable sample to obtain results I would consider statistically significant and most reports are of only a few (or couple dozen) contacts and I think a lot more than that are required (and over a significant period of time).

I hope I'm not stepping on toes here; that is not my intent.
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Antennas / Re: End fed windom
Last post by gil - February 10, 2020, 05:34:57 am
Quoteno matching needed on the most bands?

Hi, correct. I am talking about a half-wave end-fed with a 49:1 transformer, not a random wire with a 9:1 UNUN. I have built a Windom, albeit not this exact design, with a dual-core Guanella BALUN. Because the two legs aren't the same length, even with the BALUN, I had RF stray currents problems... Actually, I've had troubles with random wires and any antenna that was not fed in the middle or half-waves at the end. Now, I only use dipoles or HWEFs, sometimes quarter-waves with radials, but I avoid antennas fed somewhere in between... Too much trouble...

Gil.
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Antennas / Re: End fed windom
Last post by Oliver - February 09, 2020, 05:04:48 pm
Quote from: gil on January 06, 2020, 05:45:11 amSame as an end-fed half-wave...

Gil.

no matching needed on the most bands?


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General Discussion / Re: Encryption
Last post by BKM - February 05, 2020, 07:08:21 pm
I don't know about trying to use anything exotic as an encryption method. Isn't the idea of prepping to be able to make your life as easy as possible once you have found the need to activate those skills?

Not that many years ago when I lived in a very different part of the country, our small group was looking for something we could use to encrypt our messages between each other and it needed to be useful across any and all modes of communications. We all agreed that we would use something that might take longer to write down, decode, and then reply in fashion, but that it would have to be simple to understand. So one of the methods we devised was to use a small collection of paperback books that were easy to get and fairly universal as the basis for the code translation table.

I don't remember all of the books right now, but two of them were Dr. Seuss Cat in the Hat, and the other was Hitch hikers guide to the galaxy. Every letter of the message would be represented by a letter followed by 3 numbers. The beginning of the message would indicate the book to use along with the first letter of the message and the first letter of the message must always be from page 1 of the book. So the following message:

B107 would indicate to use Book B (Hitch Hikers Guide) and take the 107th letter from page one to be the first letter of the message.

The only other thing to remember was the letter P. So if the message contained P213 it would not be a letter but an indication to change to page 213 for the next portion of the message.

All other letters in the message would be random letters followed by a 3 digit number. The letters would be ignored and the number would indicate the letter position on the most recent page to be in the decoded message.

So a message like this:

B101 H032 D097 S239 P116 R217 L053 (and so on...)

Would be interpreted as get book B from our reading list and from page one copy letters 101, 32, 97, then change to page 116 and copy letters 217, 053 (and so on...)

This would allow clear speech without encryption and it would just seem like a numbers station. It could also be done with morse code but it might be a bit tiring without some automation. We had other ways to indicate numbers and I don't remember it all right now.

Relying on automated encryption for your secret messages requires that every participant has equally pristine working equipment. Our method meant that you could use and method code you could muster to get the message out as long as you followed the code.

I knew of groups that used the lords prayer, the pledge of allegiance, or a favorite song as long as everyone could remember it. Some used multiple similar sources and rotated them.

Could someone figure out your coding? Yeah, maybe if they were determined and if you gave them enough messages to work from for their decoding task, but it would take a long time. So, Maybe you have multiple methods with multiple sources per method and rotate everything.

I knew of one group that practiced this in the field using a set of old US Army field guide pamphlets that you can find at almost any army surplus store. They were all written back in the 1950's and 60's covering subject from first aid to emergency makeshift shelters. They carried them in their backpacks because they were thin and might not be a suspicious as say The Cat in The Hat!

There are tons of simplistic ideas that are "good enough" for emergency secret comms.

The methods I described above can be universal across handy talkies, cw, or even messages written on paper. The thing to remember is that everyone MUST be able to participate regardless of what equipment they might have functional at the time. Likewise, it must be simple to implement. I remember watching a group of 12 year old explorer scout kids do this using their memorized preparedness pledge as the source and sent the coded signals with semaphore flags!

If you force your mind to work out the simplest possible method to remember and then implement, then you can always come up with something that will work for your group.

But depending on the level of focus you can get from your group, Your mileage may vary!

BKM
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Radio Reviews, Questions and Comments. / Re: Xiegu g90 20w qrp
Last post by vy2js - February 05, 2020, 03:46:21 pm
Great thanks.

I haven't been able to find any real complaints about it.

I recently discovered that you can turn the screen off so even that niggle in the back of my mind has been put to rest.

As soon as i have the money saved I will pull the trigger.  I think pairing it with a wolf river coils silver bullet would be a good combo for base, portable and mobile use.

Additional EFHW for more portable options too.

:-)

73
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Radio Reviews, Questions and Comments. / Re: Xiegu g90 20w qrp
Last post by Pensioner Prepper - February 05, 2020, 12:45:38 pm
Hi
Had mine for about one year. Can't say I have anything bad to say about it. Got to be a absolute deal for the money.
I can that I have found the tuner to be a dream. Right up there with my KX3
Probably true to say that it comes into its own for portable operations which I believe it excels.
Hope this is of some use.
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Tactical Corner / Re: Sending Encrypted Messages...
Last post by Xcott - February 04, 2020, 08:19:22 pm
Hi,

I disagree about AES:  the algorithm is actually very transparent and straightforward.  It wasn't designed by the NSA either, nor altered to introduce any weakness.

Also, for a one-time pad you can't send someone the key file encrypted using PGP. If you did that it would no longer be a one-time pad, or to be more specific it would no longer satisfy perfect secrecy.  It would instead be a theoretically breakable cipher with the same weakness as PGP.  For a one-time pad you must transfer the pad material over a channel guaranteed to be secure, no extra encryption allowed.

If I needed a pencil-and-paper cipher I probably wouldn't use a one-time pad, because while the algorithm is super-simple, the key management is horribly complicated, and the one-time pad provides terrible security if anyone is slightly bad at key discipline.  It's an example of a cipher that goes from perfect to awful with just a tiny addition of reality.
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General Discussion / Re: Who participated in Winter...
Last post by lewisp - February 03, 2020, 06:48:02 pm
3 of us went out for it.
   Camped on a mountain top in SW Idaho, and ran wire antennas and QRP rigs. Phone and digital contacts on 20, 40 and 80.
   Weather was tough, but that's the point!!!
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Morse Code / Re: MorseFree - Free Morse Cod...
Last post by gil - February 03, 2020, 05:15:36 am
Thanks Sparks :-)
Gil.
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