Re: Topband: Hi Gain Preamps, Noise Figure Comparison (KD9SV 994 x5, W1FB, W7IUV preamps)

Don, Thanks for sharing your research on the preamps. Very informative. Your study is very timely for me. I have ordered DX Engineerings new phasing box, NCC-2. Optional plug in preamps are available for the unit. I am holding off on ordering a preamp until I compare specs with other external

Topband: ZD8W

Oliver, ZD8W asked me to post that he will be QRV on 1823.5 at 0400Z Wednesday morning his time. GL and 73, Joe, W1JR -- Joe Reisert Amherst, NH _ Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Hi Gain Preamps, Noise Figure Comparison (KD9SV 994 x5, W1FB, W7IUV preamps)

Hi JC, I did not publish any absolute Noise Figure values, my measurements that I published are all just differences in Noise Figure. It actually is much easier to measure the difference in Noise Figure between preamps that have such high gain (approximately 40dB in this case) since the noise

Re: Topband: 160 m inverted L

Agree. I use three fixed serial caps with shorting relays to tune my 160m T, 8 elevated 125' radials, across the full band in 45KHz segments. The antenna is cut for 1820 and fed with a 50::25 TLT. The voltages across each cap (3 all the same value) is well below 400v at QRO so I used

Re: Topband: 160 m inverted L

Makes sense Rob. Probably a good approach is to find the capacitance needed and use fixed vacuum caps in lieu of a vacuum variable. Then we have a bullet proof feed sys. Fixed vac caps are plentiful on ebay. I have collected a bunch of them. What height would be adequate for a 160 elevated

Re: Topband: Hi Gain Preamps, Noise Figure Comparison (KD9SV 994 x5, W1FB, W7IUV preamps)

Hi Don Measuring noise figure below 1 db is a very complicated work. First you need to remove all common mode noise, your noise floor should be better than -135 dBm at least with a 40 db preamp connected to the radio input and a 50 ohms load. You need chokes everywhere and most important

Re: Topband: 160 m inverted L

I fully agree. And wide plate spacing isn't either, even at the legal limit! I used an omega match (with two capacitors and no inductors) to match the coax to my 160m inverted-L. The largest one in the photo on my site is overkill, it's what I had. 73, Mike www.w0btu.com On Nov 8, 2016 4:55 PM,

Re: Topband: 160 m inverted L

I’ve never owned a vacuum variable. What I have been using for decades are very large air variables hung from a stick, or tree or whatever and I cover it up with a 2L pop bottle* with the bottom cut out of it. Fix in place with rope, string, tape, fishing line, whatever. I can’t take credit for

Re: Topband: 160 m inverted L

From: Herbert Schoenbohm To: topband@contesting.com Sent: Tuesday, November 8, 2016 5:12 PM Subject: Re: Topband: 160 m inverted L Bread slicers have their issues and are not really the best solution.  Herb, I must agree with you. Over 25 years ago, I tried

Re: Topband: 160 m inverted L

Bread slicers have their issues and are not really the best solution. Using a fixed high current mica G2 broadcast capacitor of a higher value than you need, and making it variable with a series inductor is the way to go. This is what broadcast stations do in their ATU's. I haven't ever

Re: Topband: 160 m inverted L

A vacuum variable for L impedance matching is unnecessary. Vacuum variable capacitors leak eventually. It take a long time for them to go through their ranges and you have to have the mechanics outside if you perform remote tuning, to sense or count turns to track when the v.v. is nearing its

Topband: Hi Gain Preamps, Noise Figure Comparison (KD9SV 994 x5, W1FB, W7IUV preamps)

Gary (KD9SV) kindly loaned me one of his 994 x5 preamps (sometimes called KD9SV VLN (very low noise) preamp) so I could compare its Noise Figure against one of my W1FB preamps as well as 2 of my W7IUV preamps in series on 160 meters. Here is a link to a youtube video I created that demonstrates

Topband: BOIG antenna changes

Years ago, before 1920, Harold Beverage ran a "wave antenna" wire on the ground on Mount Desert Island, Maine over the rocks on the shore line to a Navy Barrage receiver, near Otter Cliff's.  He discovered its directional properties. Later about  ca ~1948 Albert E. Weymouth, Original W1BX

Re: Topband: Fw: 160 m inverted L

The business of avoiding high angle radiation at all costs is a real urban myth on 160. NVIS closing of close-in skip zones on 160 can save your run frequency in contests. While creating an R=50, X= whatever feed Z is certainly useful, other issues are paramount. Reduction of current in the

Re: Topband: 160 m inverted L

On Tue, Nov 8, 2016 at 12:23 PM, Rob Atkinson wrote: > I have no idea what a "FCP" is, but it doesn't matter. > > 1. An inverted L is an _unbalanced_ antenna. Therefore you don't need a > balun. > An FCP is a Folded Counterpoise. Basically, it's an elevated radial for

Re: Topband: 160 m inverted L

I have no idea what a "FCP" is, but it doesn't matter. 1. An inverted L is an _unbalanced_ antenna. Therefore you don't need a balun. 2. This means you can feed it with unbalanced line, i.e. coax. 3. You can use an unbalanced matching network such as an L network, preferably at the feedpoint.

Re: Topband: Fw: 160 m inverted L

Charles, Thanks for the very informative post ! I am planning an install of a 160M inv L myself and appreciate the info. Bob K6UJ On 11/8/16 9:34 AM, Charles Moizeau wrote: From: Charles Moizeau Sent: Tuesday, November 8, 2016 12:32 PM To: farr...@yahoo.com Subject: Re: