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Messages - ThElectriCat

Pages: [1] 2 3 ... 8
1
Longwave Loggings / Re: New to longwave
« on: Today at 08:17 »
It looks like the same thing with a lower stopband attenuation. it probably will work just as well as long as your receiver has a reasonably robust front end. I don't even have a filter on mine, I just rely on the fact that my antenna matching transformer works poorly above 1 mhz. My receiver is actually a demodulator, and can handle a pretty strong input.

another trick that works really well if the strong local interference is on a single frequency is to shunt that one signal to ground with a series resonant circuit, this is effectively a notch filter and will provide vary good rejection on a single frequency.
 
Long story short, any filter is better than none, and you don't need a filter with super high stopband attenuation to get decent results. 

2
Longwave Loggings / Re: New to longwave
« on: February 22, 2020, 1939 UTC »
If you have about 100 bucks, and dont feel like building a filter, I have heard good things about these filters from Kiwa Electronics
https://kiwa-electronics.com/500-khz-low-pass-filter-3.html
To clarify, I don't work for this guy, nor do i have one, just passing along stuff I heard about.
 Best of luck in radios' basement     -EC
edit-(whoops, looks like its about 140 bucks)

3
Equipment / Re: Test Equipment purchase
« on: February 09, 2020, 0638 UTC »
Good frequency counters sometimes have a mode with 2 inputs where one input is counted and the count is gated by the other. This allows you to compare two signals regardless of the internal clock (or use a better oscillator, gpsdo, etc. on the second input. ) I use this feature a lot for comparing low frequency signals.

4
Longwave Loggings / Re: unid 305
« on: December 15, 2019, 1950 UTC »
I feel like I logged LT once when I lived In Shasta Lake CA, I wont say that officially though unless I can find it in my logs, seems like something I would have posted.
If I did, it certainly wasn't a strong signal

5
Longwave Loggings / Winter 2019 NDBs, Portland Oregon
« on: December 15, 2019, 1833 UTC »

NDB logs for 12/14 19 between 0500z and 0700z


200 UAB Anahim lake BC CAN
214 LU   Abbotsford BC CAN
221 QU  Grande Prarie AB CAN
223 YKA Kamloops BC CAN
236 YZA Ashcroft BC CAN
239 OJ   High Level AB CAN
242 ZT  Port Hardy BC CAN
251 YCD Nanaimo BC CAN
328 5J   Coronation AB CAN
332 VT  Buffalo Narrows SK CAN
338 ZU  Whitecourt AB CAN
341 DB  Burwash YT CAN
343 YZH Slave Lake AB CAN
344 XX  Abbotsford BC CAN
346 YXL Sioux Lookout AB CAN
350 NY  Enderby BC CAN
356 PND Portland OR USA
359 YAZ Tofino BC CAN
359 YQZ Quesnel BC CAN (this one usually beats with YAZ to the extent that they are both difficult to hear properly)
362 RPX Roundup MT USA
368 SX  Cranbrook BC CAN
368 ZP  Sandspit BC CAN (this one usually beats with SX to the extent that they are both difficult to hear properly)
374 EX Kelowna BC CAN
382 YE Fort Nelson BC CAN
395 YL Lynn Lake MB CAN
400 QQ Comox BC CAN


Received using a T antenna (in the attic of my apartment) and a WJ 8718. The antenna is matched with a 100 to 5 turn isolation transformer (100 on the antenna side)

6
Equipment / Re: 9:1 or 49:1 unun for end-fed long/random wire?
« on: October 19, 2019, 0624 UTC »
This may not be relevant to HF stuff, but the antenna I use for NDB reception has a 400:1 transformer (20:1) turns ratio. I have never tried to transmit through it, but it proved the optimal ratio for receiving with my setup.

7
Equipment / Re: Test Equipment for First Time Build
« on: September 25, 2019, 0406 UTC »
In the beginning, I wouldn't bother with a spectrum analyzer. 
+-RH
I, begrudgingly, Agree
I lusted after one of those for a long time, I finally got one (an HP8594E) aaand...
I don't really use it anywhere below a few hundred MHz. I use my scope and frequency counter every day.

my recommended top three (after the usual electrinic stuff such as a multimeter, power supply etc) are;
1. oscilloscope (my preference is analog, but any good scope is good and some digital features are really nice)
2. frequency counter (a cheapie is probably sufficient)
3. signal source. (slightly less important for building transmitters, but good luck building or even fixing a receiver without one. of course a cheap analog one is fine if used with the frequency counter. )

hope this helps _

8
Equipment / Re: These Satellite Antennas Were Inspired by Origami
« on: September 25, 2019, 0400 UTC »
This looks as far as I can tell like a foldable version of an single element axial endfire helical antenna (just a helix if you are familiar with satellite communications.
Those are usually several wavelengths long and the greater part of a wavelength or so in all other dimensions.
Pros.
        Nice wide bandwidth
        Tight beam of circularly polarized radiation
        Easy to match to 50 ohms with a flattened helix end
        Invented by John Kraus after a professor of his said "It will never work" (one does not stumble upon things this satisfying often)
Cons
        Ruining ones life by a mad, all consuming obsession to construct an antenna the size of a building and then figuring out how to point it as to work DX

9
Equipment / Re: 80M home brew Mag Loop VS. inverted L comparison
« on: September 25, 2019, 0352 UTC »
If you have both antennas, you may want to use the loop for RX, where its tuned, narrowband inherent characteristics and deep nulls will help to reduce interference from strong local stations.
Of course, for RX only, a much smaller, multiturn loop can be used if you are so inclined

10
Equipment / Re: 80M home brew Mag Loop VS. inverted L comparison
« on: September 24, 2019, 0310 UTC »
Nice work. Loops like these are always going to be lossy and bad for dx on the low bands,
this is true, but if you are interested in NVIS communications (Near Vertical Incidence Skywave), which is really good for shorter range HF communications, loops can be excellent performers.
there are lots of online resources on NVIS on ham websites for anyone who is unfamiliar.

11
probably going to get yelled at for mentioning my favorite receivers, but...
Watkins Johnson receivers, have s meters that are somewhere in between log and linear scale, and are extremely useful for setting the RF gain manually, but I am pretty sure thats what they are for. I can't really find a better way to use them. some of the clearest signals I can hear barely deflect them, and some of the worst do.

12
Equipment / Re: Filters For Dummies
« on: August 17, 2019, 1622 UTC »
One of the simplest FM filters which can be reasonably practical for the homebuilder are made from coax.
They rely on the fact that a quarter wave stub can either look like a short or an open circuit depending on whether it is open or shorted respectively. 
Get a coax tee, and connect a quarter wave of good quality coax to the tee solder the far end of it together (conductor and shield) and put the tee inline with your feedline.
This is, in fact, electrically very similar to a cavity filter, but with a little bit more loss and lower Q, but it is much cheaper and more homebrew friendly.

Remember that a quarter wave will be a normal quarter wave in free space multiplied by the velocity factor of your coax, which you should be able to look up (usually 0.6 to 0.8)

Make sure to include the length added by the coax tee and measure as accurately as possible.  A big advantage of these filters is that they are a short circuit at dc. When I worked in broadcast, I would put them in between the exciter (usually a 20 or so watt transmitter) and the 30 Kw power amplifer, that way DC spikes caused by transmitter problems wouldn't kill the solid state exciter. 

some things to be careful of.
make sure your transmitter is ac coupled, if the plate/collector/drain voltage is present on the output, this filter won't work
if you are transmitting more than a watt or so, hook up the filter and run it, make sure its not getting warm. if you have it cut for the wrong frequency, your transmitter will see a very bad vswr, and the filter will dissipate as much power as the loss in the coax allows.

13
Other / Re: Racist ramblings on 80m
« on: August 17, 2019, 1605 UTC »
I actually Have a ham license, but hardly ever use it for the same reasons. Don't get me wrong, when I used to be on the air all the time, I met lots of good people, but there's too much of an old boys club, eager to tell anyone new exactly how the best hams should do things, that combined with people like those in the original post, and a lack of desire to say "hello, where are you. OK goodbye!"  as the primary radio type of conversation, pushed me away from ham radio.
Most of the really interesting stuff is unlicensed anyway.

14
Other / Racist ramblings on 80m
« on: July 29, 2019, 0456 UTC »
wow, I have heard a surprising amount of recordings/shouting sessions on 80 meters, (currently 3908 Kc, 0454 utc, 7-28-19)
lots of sexual, anti semetic, anti/pro trump, pro rape, anti/pro religious and other dirty content
featuring callsigns which may or may not actually belong to the hams involved.
I have heard these significantly more in the last year or so.


15
Thats a really cool transmission method, (and an image worthy of broadcasting)
I have seen some of the C-MT and S-MT hell methods used for QRSS, but never anything that actually draws any image of high resolution or span in a waterfall.
Nick work!

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