Accessories for my Rock Mite ][

Started by NWARadio, April 27, 2014, 05:48:30 pm

Previous topic - Next topic

NWARadio

April 27, 2014, 05:48:30 pm Last Edit: April 27, 2014, 06:35:05 pm by NWARadio
Ok, so I've ordered a 40m RM and found a plastic enclosure on Ebay. I'm wondering about this filter: http://midnightscience.com/kits.html is just a CW filter, right? I don't understand the "center frequency" bit. And will this work with the RM40][ that I've ordered?
So long, and thanks for all the fish

KK0G

Quote from: NWARadio on April 27, 2014, 05:48:30 pm
Ok, so I've ordered a 40m RM and found a plastic enclosure on Ebay. I'm wondering about this filter: http://midnightscience.com/kits.html is just a CW filter, right? I don't understand the "center frequency" bit. And will this work with the RM40][ that I've ordered?

Yes, it's an audio filter for CW. The center frequency is the frequency of the CW tone you'll hear, personally I'd go with 700 Hz. Yes it will work with the RM or any CW rig.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G

cockpitbob

Consider the switched capacitor CW filter kit by NewEngland QRP.  Not a bare-bones as a passive LC filter, but much more capable for about the same price.  At the top-left of the page is the link to their store.

I like their slogan:  "The excitement is building."

NWARadio

Thanks for the replies. I'll take a look at both filters. Now, is this like a filter that I'd get for my Icom that'll neck down incoming signal and reject nearby signals so I only hear what I'm hoping to hear? The RM][40 comes with a built in picokeyer, so I went ahead and ordered this paddle: http://www.americanmorse.com/dcp.htm. Hopefully I won't screw this up. lol I'll post pics as I go.
So long, and thanks for all the fish

KK0G

Quote from: NWARadio on April 27, 2014, 08:02:41 pm
Thanks for the replies. I'll take a look at both filters. Now, is this like a filter that I'd get for my Icom that'll neck down incoming signal and reject nearby signals so I only hear what I'm hoping to hear? The RM][40 comes with a built in picokeyer, so I went ahead and ordered this paddle: http://www.americanmorse.com/dcp.htm. Hopefully I won't screw this up. lol I'll post pics as I go.

Yes and no - how's that for an answer? ;D

The filter you'd put in your Icom is an IF (intermediate frequency) filter which filters the signal to the bandwidth of the filter before it goes into the next stage of the receiver - highly effective but obviously more complex and consequently costly.

What you're looking at is an AF (audio frequency) filter. The signal you're trying to filter has already been through every stage of the receiver and consequently amplified at each stage and is now at the audio jack of your rig waiting to be pumped into a speaker - this is the point where you're filtering. Not as effective as as an IF filter but has the advantage of being extremely simple, with no installation needed other than plugging it in between the receiver and speaker, and it's dirt cheap.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G

NWARadio

Sounds good. I don't have any electronics training and no real Elmer, so I'm learning as I go the best I can. Lots of things I don't understand.

So long and thanks for all the fish.

So long, and thanks for all the fish

gil

Whether you'll need a filter or not depends on your location. Where I live, if I turn on my RM40, I am pretty much guaranteeed to hear music in the earphones! Fortunately my magnetic loop antenna filters that out, but my end-fed does not. An audio filter will filter some of it out, but not all.. I am waiting for my RM30 right now, I wonder if it will do the same! As the the DCP paddles, they work great.

Gil.

cockpitbob

Quote from: NWARadio on April 27, 2014, 08:39:17 pm
So long and thanks for all the fish.
This just cost me 5 minutes.  It made me think, if 73 is "best regards" and 88 is "hugs and kisses", what is 42?  It looks like Western union didn't have a 42 code.  There's  39 "important, with priority" and 44"answer promptly" but no answer to the meaning of life, the universe and everything.  :o

KK0G

Quote from: cockpitbob on April 27, 2014, 08:56:28 pm
Quote from: NWARadio on April 27, 2014, 08:39:17 pm
So long and thanks for all the fish.
This just cost me 5 minutes.  It made me think, if 73 is "best regards" and 88 is "hugs and kisses", what is 42?  It looks like Western union didn't have a 42 code.  There's  39 "important, with priority" and 44"answer promptly" but no answer to the meaning of life, the universe and everything.  :o

The answer is 3 :o
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G

KK0G

Quote from: NWARadio on April 27, 2014, 08:39:17 pm
........Lots of things I don't understand.

Join the crowd. ;D

"Live as if you were to die tomorrow, learn as if you were to live forever." - Mahatma Gandhi
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G