Re: Topband: "Thinking out loud"

ssage- >> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Matt >> Murphy >> Sent: Thursday, December 22, 2016 11:19 PM >> To: k...@myfairpoint.net >> Cc: Topband <topband@contesting.com> >> Subject: Re: Topband: "Thinking out loud&qu

Re: Topband: "Thinking out loud"

ontesting.com> Subject: Re: Topband: "Thinking out loud" This appears to be the 4O3A unit. I hadn't realized these existed, so I'm glad you posted the question: http://www.4o3a.com/index.php/products/ham-radio-gear/crystal-front-end-unit / On Thu, Dec 22, 2016 at 3:47 PM, K1FZ-Bruce &l

Re: Topband: "Thinking out loud"

, 2016 11:19 PM To: k...@myfairpoint.net Cc: Topband <topband@contesting.com> Subject: Re: Topband: "Thinking out loud" This appears to be the 4O3A unit. I hadn't realized these existed, so I'm glad you posted the question: http://www.4o3a.com/index.php/products/ham-radio-gear/c

Re: Topband: "Thinking out loud"

Thanks for the information Stew.  Originally I tried it at my parents QTH on 40 meters when I was teenager. Was licensed in 1950 as W1TJQ.   Ideas get lost and time goes by.  In the 1920 Hugo Ginsburg ( not sure of his last name spelling)  in a book at the Belfast Library said silicon looked

Re: Topband: "Thinking out loud"

The SNR is set at the antenna. There is a persistent desire to move the selectivity closer to the antenna, however With modern "bullet-proof" front ends, filtering can be delayed and done at i-f. In fact, with H-mode mixer front ends, the IMD in the following filter can be more of a

Re: Topband: "Thinking out loud"

One must remember that the purpose of these filters is to reduce the total energy presented to circuitry that would otherwise be overloaded by it, or create crud at any level because of the poor IMD characteristics of the radio circuits. I did something of the sort at W4BVV in the 1960's with

Re: Topband: "Thinking out loud"

Years ago at the W3GM M/M station, Gerry had several crystal filters (50 ohm Z input & output) in the 40M RX path. As I recall, these were about 20-30 khz wide (each) and were of slightly different center frequencies so that most of the 40M CW band could be covered. I DO remember that they

Re: Topband: "Thinking out loud"

Hi Bruce "We know that limiting the noise pick up from more directions of an antenna we can usually hear better" Agree, actually the directivity of the receiving antenna is the only place you can increase signal to noise ratio. More RDF means more directivity (3D) resulting better signal to

Re: Topband: "Thinking out loud"

Hi, I wonder if you could cover the whole band or just the part that interest *you*. I have a radio now that uses an xtal filter with about a 7 kHz bandwidth on the 20 meter band. Probably those filters can be made wider with perhaps less filtering action - tradeoffs ya know. The idea isn't

Re: Topband: "Thinking out loud"

This appears to be the 4O3A unit. I hadn't realized these existed, so I'm glad you posted the question: http://www.4o3a.com/index.php/products/ham-radio-gear/crystal-front-end-unit/ On Thu, Dec 22, 2016 at 3:47 PM, K1FZ-Bruce wrote: > > Thanks Mirko, > > > Very Good

Re: Topband: "Thinking out loud"

Thanks Mirko,   Very Good information.   What is needed is to reduce noise lower than signals. 73 Bruce-k1fz   On Thu, 22 Dec 2016 22:36:30 +0100, S57AD wrote: As far as I recall, Inrad sells front-end xtal filters. Some 25 years ago when I lived in Belgrade, at YU1EXY we had two

Re: Topband: "Thinking out loud"

As far as I recall, Inrad sells front-end xtal filters. Some 25 years ago when I lived in Belgrade, at YU1EXY we had two six-pole filters for SSB part of 40M band but I can't recall and difference with or without those filters. Beside those two xtal filters we used 8 pole Cohn LC filter with

Re: Topband: "Thinking out loud"

  160 meters is above the broadcast band. 3rd order should be above 160, not lower. lattice filters, many near 9 MHZ. for single sideband transceivers,  are used successfully. Could take out more noise, than adding.   All the arguments against this could also be used against roofing filters.

Re: Topband: "Thinking out loud"

Tim,   My single crystal was in the 1950's.   A crystal lattice could take in much of the 160 meter band and be pratical.   Thanks for your input.   73 Bruce On Thu, 22 Dec 2016 15:49:12 -0500, Tim Shoppa wrote: Bruce -  It has long been rumored that the big EU multi-multis have a

Re: Topband: "Thinking out loud"

Crystal filters are known to have a 3rd order intercept point. Depending on how many AM BCB stations impinge on your filter, you could get intermods. Switching in an attenuator ahead of the filter should help, if you can stand the increase in noise figure. Rick N6RK On 12/22/2016 12:41 PM,