Re: Topband: Commond mode choke for Beverage

On Mon,10/12/2015 6:51 AM, Filipe Lopes wrote: With these ferrites I ask the same question, should I put the choke close to the 9:1 Balun or near the switching box and how many turns? some bevs have the feed point at +- 60m away from the switching box. Use the #31 material. Wind at least 20

Re: Topband: Commond mode choke for Beverage

On Mon,10/12/2015 5:45 AM, Filipe Lopes wrote: I am about to add a common mode choke to isolate the antenna from its feedline to each of my beverages and I only have FT240-61 ferrites. #61 is a terrible material for use as a common mode choke below 500 MHz. Try to find #31 or #43, and wind

Topband: High Pass Filter

"Where can I find a schematic for a good high pass filter that rolls off at 1700 kHz?" Hopefully with permission of the moderator I suggest you might look at our inexpensive filters. The specs are good even at 1.7 MHz http://arraysolutions.com/Products/AS160HPF.htm Jay Terleski President Array

Topband: FW: Commond mode choke for Beverage

Felipe, I just now built & tested what you need. I tried 7 & 8 turns, but it resolved too high in freq. Use 9 TURNS on a core-stack of five (5) of P/N 2631803802 cores. That’s the Mix #31 core. For the choke windings, make the windings VERY tight to the core-stack. To do that,

Re: Topband: FW: Commond mode choke for Beverage

On Mon,10/12/2015 8:23 AM, Bill Hider wrote: Use 9 TURNS on a core-stack of five (5) of P/N 2631803802 cores. That’s the Mix #31 core. Bill, A 5-high stack of cores is only needed to handle high power. This is an RX antenna, so suitable choking Z can be obtained with more turns on a

Topband: Commond mode choke for Beverage

Hi guys, I am about to add a common mode choke to isolate the antenna from its feedline to each of my beverages and I only have FT240-61 ferrites. My question is how many turns should I do on the ferrite using RG58 (all my bevs are fed with RG58). Also should I put the choke near the 9:1 balun or

Re: Topband: Commond mode choke for Beverage

Hi Filipe Zero , you should use material #31 or #77 , The core you have is not good for low bands. JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Filipe Lopes Sent: Monday, October 12, 2015 8:46 AM To: topBand

Re: Topband: Commond mode choke for Beverage

If you must use FT240-61, then in a single layer about 18 turns of RG58 would fit, which should give you ~600 Ohms on 1.8 MHz. That would be very good for a dipole, but for a Beverage a much higher impedance is needed. Try to fit as many turns as possible, until there is no more room in the

Re: Topband: Commond mode choke for Beverage

Hello JC, Thanks for your answer. I just ordered a few 2631803802 and 5943003801 from mouser. With these ferrites I ask the same question, should I put the choke close to the 9:1 Balun or near the switching box and how many turns? some bevs have the feed point at +- 60m away from the switching

Re: Topband: Commond mode choke for Beverage

With 5943003801 and RG58, closely fill-in a single layer, leaving 10-15 mm on the outside perimeter unused. That should be ~16 turns, giving you impedance near 4000 Ohm. Such a choke should be placed close to all points where the current on the outer surface of the coax shield can pass to the

Re: Topband: High Pass Filter

On 10/12/2015 9:03 AM, Jay Terleski wrote: "Where can I find a schematic for a good high pass filter that rolls off at 1700 kHz?" Hopefully with permission of the moderator I suggest you might look at our inexpensive filters. The specs are good even at 1.7 MHz

Re: Topband: Commond mode choke for Beverage

>> With these ferrites I ask the same question, should I put the choke close >> to the 9:1 Balun or near the switching box and how many turns? some bevs >> have the feed point at +- 60m away from the switching box. My two cents..It was interesting during the installation of the last

Re: Topband: Commond mode choke for Beverage

Thanks Jim and all for the help. Mix #31 cores are already ordered in mouser. 73's cu on low bands Filipe LOPES CT1ILT CR6K Sent from my SAMSUNG GALAXY S4 Em 12/10/2015 17:39, "Jim Brown" escreveu: > On Mon,10/12/2015 6:51 AM, Filipe Lopes wrote: > >> With these

Re: Topband: High Pass Filter

It is shown with RCA connectors. Is it available with F? BNC? I have generally found RCA connectors to be unsatisfactory in the long term for a variety of reasons generally revolving around the "Astro" plate hard nickel surfaces. A large number of 160 receive antenna systems are built with

Re: Topband: ADC Overload

>"The favorable SDR averaging doesn't apply when the RF voltage at the receiver >input is dominated by one huge signal, and if that signal exceeds the >capability of the ADC in the radio, overload can definitely occur. So, >although I believe that nearly all manufacturers will soon migrate to

Re: Topband: ADC Overload

Interesting comments, Steve, and to me quite on the mark. (In an ealier life, I was a physics prof, though I've forgotten most of what I once knew). Re the comment by another list member that "there are various distractions such as the Central Limit Theorem...that don't add much to the

Re: Topband: Commond mode choke for Beverage

Hi Felipe It works like a voltage divider where the impedance to ground should be lower as possible to give you more attenuation like 1k/500ohms versus 1K/5 ohms divider. You should use the choke near a good ground before entering the station. If you switch box have a good ground it’s a

Re: Topband: ADC Overload

Then what if we *deliberately* inject hundreds, if not thousands of discrete RF carriers into our SDR receivers from say...an internal RF carrier or noise generator, mixed with the desired RF signal to mitigate OL caused by a few strong carriers? It would be interesting to see the math and

Re: Topband: Commond mode choke for Beverage

Eduardo Araujo via Topband wrote: > My two cents..It was interesting during the installation of > the last beverage, we have only #31 core, so we placed it at the > receiver side. Disconnecting the coax at the bev feed point and > shorting the coax there, many AM

Re: Topband: ADC Overload

Hi Guys It's well know the ability to copy weak signal near strong carriers. I run a QS1R using HDSDR all the time shearing the same RX antenna with my IC7800. In the last 10 years only once I worked a new country on 160 listening on the SDR that I was not able to copy using the IC7800. David

Re: Topband: ADC Overload

On Mon, Oct 12, 2015 at 10:28 PM, Mike Waters wrote: > But as a recent thread here* established, there is *NO* SDR that can > perform as > well as a good ear-brain combo for copying the very weakest of signals > buried in the noise. Maybe someday, but the future has not

Re: Topband: High Pass Filter

Switchcraft and Neutrik both make excellent RCA male cable-mount connectors. They are easy to terminate, and the shell will accept cable with an o.d. of about 0.25-in. They can be used with RG58 and RG59 cables having a copper braid shield. I buy stuff like this from Full Compass, near

Re: Topband: ADC Overload

Hi Barry, Thanks for your input. Yes, I believe we included direct sampling digital receivers (SDR) versus superhet receivers. The post I made here today is not complete; rather that re-post everything, I included a link to the early August discussion, which explained in detail what I meant.

Re: Topband: ADC Overload

An SDR is better for several things, yes. One advantage is that near-perfect extremely narrow filters can (and do) exist in software. But as a recent thread here* established, there is *NO* SDR that can perform as well as a good ear-brain combo for copying the very weakest of signals buried in the

Re: Topband: Commond mode choke for Beverage

On Mon,10/12/2015 1:27 PM, JC wrote: It works like a voltage divider where the impedance to ground should be lower as possible to give you more attenuation like 1k/500ohms versus 1K/5 ohms divider. Yes. But to expand on this -- often the interference is coupled into a gain stage or RX by

Re: Topband: FW: Commond mode choke for Beverage

I tried 7 & 8 turns, but it resolved too high in freq. Use 9 TURNS on a core-stack of five (5) of P/N 2631803802 cores. That’s the Mix #31 core. The attenuation of any choke significantly depends on the common mode impedance, and impedances from shield to ground. Many times just a few

Re: Topband: ADC Overload

Jim, I sense a flaw in the CLT argument, which is likely a lack of understanding on my part. What you are describing sounds more like AGC action. In-other-words, moving the minimum detector level up the bell curve such that we have now lost any capability of listening down into a hole