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   Home   Help Search  
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 1 
 on: Today at 07:32:50 AM 
Started by WA9CFK - Last post by W9IQ
These antennas are 4 short, top loaded verticals fed with 1/4 wave, paralleled phasing sections to yield a 50 ohm feedpoint impedance. With proper construction techniques the efficiency can be quite high. Due to the close proximity of the vertical elements, it acts like a cage antenna.

Something to think about for 630 meters, et al when you are height limited and looking for an omni antenna.

- Glenn W9IQ

 2 
 on: Today at 07:30:27 AM 
Started by NEVBEN - Last post by AA4PB
The first thing you need to do is apply for a variance for whatever antenna/tower you want and have your public hearing. They may approve it if you provide some justification and get the support of neighbors.

 3 
 on: Today at 07:30:11 AM 
Started by K7JQ - Last post by K7JQ
Just saw it on QTH.com. Have at it!

 4 
 on: Today at 07:25:17 AM 
Started by NEVBEN - Last post by GW3OQK
Hello Nevben, in the MN I used the Aldis Lamp, which has a trigger on the handle operating a conical shutter. It plugged into a 12v battery which was carried out to the bridge wing. On a passenger ship I used the 12 inch lamp which had a crank-handle on the side to operate the shutters. We signalled at no more than 10 wpm I think, for I just tried sending Paris, which took 8 seconds. To call a ship you sent "AA" and to acknowledge each word sent "T". If you didn't get a T then the word was repeated.

The normal exchange was our ship's names as we passed by on the open ocean. To receive a proper message such as berthing info or a passenger list you had to have someone to write it down as you called it out. I had an advantage over the mates as an R/O. If you had to receive using binoculars it became a great strain on the eyes. The Mates, especially as they got more senior, distained the lamp and were very likely to call for Sparks, or just send a T without reading the word.

On optical communications I have read about using LED and laser to send and receive data and SSB remarkable distances in recent years.
all the best
Andrew

 5 
 on: Today at 07:25:08 AM 
Started by VK3LU - Last post by KJ4HVL
Also note that using the front BNC connector results in less battery drain as the rear connector is switched in using a non-latching relay.

 6 
 on: Today at 07:23:52 AM 
Started by AF5CC - Last post by AE5GT
While it is possible to listen and transmit at the same time on one antenna , you'll need to build or buy a diplexer/triplexer , I run 2 K3s into a Bencher Skyhawk with a hombrew diplexer, The more power you want to run the more adjacent band rejection you need.

You also should use a switching  network again either buy or build with band decoders. You want to slave or interlock one Xcvr to the other so if both happen to be on the same band ones antenna is shorted to keep the receiver from overloading .


Even if you use 2 antennas you either need to reduce power QRP and carefully arrange the antennas , or use band filters , or D all of the above.


if you just want to listen you can mute the slaved receiver.

 7 
 on: Today at 07:16:24 AM 
Started by NO9E - Last post by WO7R
Rigs I have actually taken to fly-in locations:

SDR 1000 (obsolete, but quite workable back in the day)

FT857D  (it was my backup rig).  Worked well for trivial places.  Very compact and capable.  Ergonomics not perfect, but usable.  Would not take this somewhere rare, receiver not good enough.  Still, it shows that you can make "the rig you have" work if you have the opportunity to go somewhere.

KX3 plus 100 watt brick.   I don't think this one was mentioned before.  The radio plus brick fits nicely in the Pelican 150 case plus a few other accessories.  You need a power supply and an antenna in some other suitcase, but you can get on the air with this and have fun.  Probably would prefer the K3 for more serious work and, indeed, that's what my buddies brought along for the 6m work.  But the receiver on the KX3 was very good, which matters a lot.

 8 
 on: Today at 07:15:17 AM 
Started by AK0B - Last post by KE4OH
You asked, so here is my advice:

Build a simple 2-tube MOPA (master oscillator, power amplifier). Hard to beat the 6AG7 as an oscillator. It is easier on crystals than most and the metal envelope is automatically RF shielded. Since you're going to build anyway, use an output tube with some grunt. There is no reason to be QRP unless that's your "thing". Think about an 807 (or 6BG6, which is an octal version). With a decent power supply (think 500-600v @ 100ma), you can easily get a good 30w or more out on 80m and 40m. A pair can get you nearly twice that.

Once you get that working with crystals, you can add a VFO. Plenty of old Heathkit VF-1s and HG-10s out there if you want to stay with tubes. Or build your own, if you dare!

I applaud your intent!! Now, go ye forth and homebrew!!!

73 de Steve KE4OH

 9 
 on: Today at 07:14:07 AM 
Started by KE2KB - Last post by N7EKU
Hi Frank,

I think you are right that the line voltage is momentarily dropped just enough for the UPS to kick in.  It makes sense since it is only doing it when you turn on the Astron.  Even a heavy AC line can drop voltage, the magnitude depending also on the length of the run and the peak inrush current.  And it depends too on how all the interconnections between the outlets are done and how many there are.  It also could be that the AC ammeter is not capturing the actual peak current.  The peak could happen faster than it can record.  And those UPS have really fast response times for correcting line voltage variations.

I don't think it would hurt the UPS though as they are designed to kick in on undervoltage and by the time they do, the Astron is probably most of the way going.  You could always change to a switching type supply which don't load the AC line on turn-on like that.  Or I suppose it wouldn't be too much trouble to install a soft-start circuit on the power supply.

73,


Mark

 10 
 on: Today at 07:11:56 AM 
Started by OM2GM - Last post by KA5IPF
I can get to the website but it's way out of date. Last update Feb, 2015.

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