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   Home   Help Search  
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 21 
 on: Today at 12:34:34 PM 
Started by G4IJE - Last post by G4IJE
Does anyone know if the SWR metering on the FT-991A is supposed to work on 2m? I have used a couple of different antennas and they both read 1:1 across the band, which seems a bit too good to be true. I don't have materials to hand to build a non-50ohm load to test it.

Thanks and 73, Paul G4IJE.

 22 
 on: Today at 12:28:49 PM 
Started by KD7QLU - Last post by AC5UP
ISome of us, (myself included) do not even get overly concerned with say a dB or two for most HF operations.

Since the OP used 14.250 MHz as the hypothetical frequency of interest let's assume typical HF skywave propagation where a 20 dB fade is not uncommon.  And does not terminate the Q.

Translation:   Minimize, but don't sweat the inevitable loss in the antenna system.  Condx will almost always determine Q or No Q and that you cannot control.

Build the best you can manage with available space and budget then try to be in the right place at the right time when a band opening makes it all worthwhile.............

 23 
 on: Today at 12:21:56 PM 
Started by K8PC - Last post by N3OX
I compared a 4 foot octagon loop with my other antennas, never really used it as my main antenna, but it worked well http://n3ox.net/files/magloopnew_lg.jpg

It had a nice Jennings vacuum variable capacitor and it was able to tune from 60m up through 15m.

I feel like 1-2S units down is similar to what I've seen with my loop in real testing and in line with predicted losses for a good loop. The other drawback is constant retuning, but that wasn't a huge deal either.

It's kind of hard to beat a magnetic loop for being able to pick any band and set it up quickly and for being a totally self-contained antenna.

There are other compact antennas that can do a lot better. I built a 10 foot vertical for 40m that would work fine on 40/30/20 with coil tap switching: http://www.n3ox.net/projects/n3oxflex

I eventually implemented tap switching for 30/40 and it was my summer 30/40 antenna after I built it. I didn't really worry about taking it down. My alternate antenna for the lower bands was 60 feet tall and even with proper station grounding always stressed me out in summer Maryland thunderstorms.

It would be really easy to lay that over on a hinged base. Very lightweight. Would easily handle legal limit. And it had a combination of nice tuning range (which could be easily motorized) and a pretty wide SWR bandwidth even without retuning. Of course it needs radials, which can often be a deal breaker. But that antenna was only 1dB down from a full-sized 40m vertical.

 24 
 on: Today at 11:50:05 AM 
Started by KD7QLU - Last post by KL7CW
I always consider the whole system.  Lets just say for example your extra coax loss is 0.5db.  Then lets assume you use a 2 element Yagi instead of a 3 element Yagi...lets say it is an additional 1.5 db loss.  Then lets say you only put it up 30 foot instead of a 40 foot tower...lets say that is an additional 2 db.  Then lets say you have lots of jumper cables and relays...lets say an additional 0.8db. etc.  You get the idea.  These fictional numbers add up to 4.8 db additional (possibly avoidable) loss.  Now most of us would agree that in many situations that 4.8 db of additional loss is sometimes significant...it is nearly an S unit.  So since I am on a budget, I try and figure out how to get the most "bang for the buck".  Much of my operation is on 1.8 to 21 MHz and my coax run was not real long...so in my case only...I selected a 3 element Yagi and put it up 60 feet.  I was not worried about the additional fraction of a dB from my medium grade of coax.  If my main interests were on 28 MHz and above, a higher quality of coax very well might make a significant difference in Tx and Rx performance...run the numbers. For EME or other VHF/UHF weak signal work a dB (or possibly even less) is big. For most of us who casually work HF a fraction of a dB of additional loss or even say a dB would not be a big concern....just do not have lots of 0.5 or 1.0 dB avoidable losses which can add up. Some of us, (myself included) do not even get overly concerned with say a dB or two for most HF operations.
     Rick  KL7CW   Palmer, Alaska

 25 
 on: Today at 11:49:05 AM 
Started by VE6MB - Last post by DL8OV
And once you've purchased and set up this miracle of technology you'll need a transceiver to work through it. How about a Kenwood TM 742A, a bargain at $3988.88 from the same seller!

http://www.ebay.com/itm/KENWOOD-TM-742A-2M-440MHZ-SHF-1-2GHZ-HAM-RADIO-POLICE-FIRE-EMERGENCY-SCANNER-FRE-/112343235814?hash=item1a282dbce6:g:xawAAOSw32lY0cEk

Peter DL8OV

 26 
 on: Today at 11:39:52 AM 
Started by K8PC - Last post by KE6EE
Because of lightening and a previous strike about 15 years ago that took out the kitchen and living room.  The XYL wants them down when storms are near.  

Certainly it is sensible to take precautions especially if one lives in lightning country.

I am wondering what evidence from the previous strike convinced you that an antenna was the problem.

I am also wondering whether your antenna system is properly grounded outside your house.

All that said, a dipole can be a very useful and simple antenna with an efficiency which easily exceeds a small loop.

If a dipole is installed as an inverted V with ends within several feet of the ground, then a single pulley at the center support
can easily drop the whole antenna if a storm approaches.

Lots of alternatives out there!

 27 
 on: Today at 11:32:17 AM 
Started by KI6TRA - Last post by KE6EE
The Chameleon P-LOOP 2.0 is a natural evolution in man-portable magnetic loop antennas. It's lightweight,  has a small breakdown

This really isn't the proper place for advertising or otherwise promoting products. It's really about asking and answering questions
about antennas and related topics.

If you are independent of Chameleon and you want to talk about how good a product is, then the appropriate place is in the eham reviews.

If you have questions about how the antenna you are promoting actually works, then a post may be appropriate.

 28 
 on: Today at 11:27:56 AM 
Started by K8PC - Last post by AF7ON
I've been playing with a few small loops (3-foot to 6-foot diameter) and am using an MFJ 1786 as a reference for testing.  I have operated it during thunderstorms by moving it under an outside deck from its normally more exposed position.  Concerns about lightning are quite valid!

Compared with other full-size antennas (doublets and quad loops up about 40 feet), the 3-foot loop mounted on a tripod at 6-feet is usually down 1 to 2 S points, but not always.  It has sometimes out-performed a full-size vertical dipole.  The MFJ 1786 has proved quite effective on 10 through 20 meters and reasonably OK on 30 meters.  If propagation is decent, you will be able to operate reasonably well, especially on CW and digital modes.  For 40 meters, you will need a bigger loop (5 to 6 feet) and likely more power (>100 W) to operate SSB reliably.

Mike
AF7ON

 29 
 on: Today at 11:18:49 AM 
Started by KB2FCV - Last post by W8JX

BTW: WHY do you keep referring to "CB"?  Are you one of those former CB operators that feels the need to let everyone know how superior you are now that you have license?


Because "modern" ham radio is a high dollar CB for many as it is a joke to get a license today as you have to really know nothing to get one so why should you care if it cause problems because many do not understand much more than using a power button and a VFO knob. There was a time when ham were far more sensitive to causing problems and were far more knowledgeable too. Not today as fewer of them are left and number is shrinking...

 30 
 on: Today at 11:12:23 AM 
Started by KG7MWW - Last post by W8JX
You need a tuner after amp but if you get a AL80b instead you get more power and ability to match to a 2 to 1 or bit more SWR without a fuss. The SWR meter will still show SWR but tuning and load control will match output to SWR and amp will be fine. (something tube amps can do that SS amps cannot)

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