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   Home   Help Search  
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 51 
 on: Yesterday at 11:59:40 PM 
Started by KC9ZMT - Last post by G3RZP
The W3EDP was relatively popular in the 1930s. 83 feet of wire, with a counterpoise of either 6 feet for 20m and 14 feet for the other bands. Fed from a parallel tuned circuit link coupled to the coax feeder. The tuned circuit dimensioned with 1.5pF of tuning capacity per metre of wavelength.

Although I did well with a water pipe ground in an upstairs apartment.

 52 
 on: Yesterday at 11:52:53 PM 
Started by KK7KZ - Last post by G3RZP
The usual advice on ceramic tubes is to run them with heaters (and airflow) only for 24 hours. The getters are apparently part of the cathode structure.

 53 
 on: Yesterday at 11:50:37 PM 
Started by WB5AGF - Last post by G3RZP
As far as SS amps are concerned, the high order IMD products are really the ones to worry about: they are far more significant in an SS amp than a tube, for obvious reasons. So even if the 3rd order is comparable or even better than the comparison tube amplifier, the levels of the higher orders need to be considered.

 54 
 on: Yesterday at 11:06:02 PM 
Started by G0DOQ - Last post by KJ6ZOL
I should note that I recently read an article on MSNBC that claimed that the global network of fiber optic cables that carry internet traffic will reach capacity in around 2023. This is due to companies putting everything online to "save money" and due to bandwidth hogging apps like streaming movies. Most of the world's fiber was installed during the dot.com boom in the 90s by a since long defunct company called Global Crossing. They believed that what they installed would be far more than enough bandwidth for decades. Back then, people used dial up net connections. Web pages were mostly text and photos. They simply didn't see the spread of cable internet. So, apparently the US military is experimenting with HF as a way to carry data traffic. Some sort of internet throttling is probably assured in a few years. There is little appetite by big internet providers to install new fiber. The big American providers are still upset over being regulated as a utility. Overseas, high speed internet is largely provided by governments. There simply isn't the money or will to install new fiber, and Obama is too corrupt and lacks the vision to start a REA-type program to lay fiber.

 55 
 on: Yesterday at 10:37:10 PM 
Started by SOFAR - Last post by K3KRN
 i've had 2 of them for about a year and they are very solid. highly recommend.

 56 
 on: Yesterday at 10:10:11 PM 
Started by 3Z9DX - Last post by N0UN
Dom, donation sent  Smiley

Powodzenia Brat

N0UN
N0UN's Ham Radio Blog

 57 
 on: Yesterday at 09:56:06 PM 
Started by K1YTG - Last post by VK2TIL
Download the LM3914 data sheet; it has a wealth of information on applications of this device.

Up to ten LEDs can be used; twenty or more by simply cascading two or more LM3914s.

High sensitivity may be obtained as I did with a simple op-amp; the feedback resistor values in my circuit were for 18-30mV range but any other range can be obtained by changing values.  The data sheet for the op-amp you use will help; Texas Instruments have wonderful application notes on op-amps.

My device had two adjustments, one for initial turn-on and one for final LED turn-on; each finished instrument was calibrated before despatch.

An alternative for your requirement might be a separate current and, perhaps, volt meter in a little case on your desk.

I recently built a little power supply;




using a small V/A meter from ebay.  It's small because the raw DC comes from a laptop power supply; there isn't much inside the case.

All you would need would be a suitable meter or two in a small case; the ammeter would be of the separate-shunt kind to simplify connections.  Shielded cable to the power supply should prevent any interference.


 

 58 
 on: Yesterday at 09:43:52 PM 
Started by NU1O - Last post by KD8MJR
I heard Monk Apollo for at least 4 or 5 years and was never able to make it, then one day I got lucky and caught him at the very start of a pileup.  Same thing with Wim in Cambodia, it took me 6 years but I finally got through.  If this hobby was easy I would not be interested in it.

73s
Rob

 59 
 on: Yesterday at 09:33:31 PM 
Started by KE7GVK - Last post by KD8IIC
  Well said OM! I too have a lot of receiver and audio filtering investment here as well and it makes working in these poor conditions a lot easier esp with the QRP ops. I just turn off the MSC Smart filter if I have a second thought about it and am just amazed at the result of almost no signal to copy. So YES, we are trying to hear you but still need your RF to tickle the detector circuit...  Cheesy
 VY 73  lane  de n8aft  sk  ..

 60 
 on: Yesterday at 09:06:07 PM 
Started by K1YTG - Last post by K1YTG
The power supply will be going under the desk.  So it would be hard to get down there with a flashlight to read a lcd or a meter.
The circuits given here will do very well to have an indication that can be seen at a distance and reduced light.
Thanks, Norm

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