Search found 213 matches

by snn47
Thu Sep 05, 2019 4:44 pm
Forum: RTL-SDR Discussion
Topic: Identifying a Device's Transmisssion Frequency
Replies: 3
Views: 987

Re: Identifying a Device's Transmisssion Frequency

Sorted in order of price
absorption meter,
frequency counter,
oscilloscope or
spectrum analyzer available can detect or meassure transmitt frequencies.
by snn47
Thu Sep 05, 2019 4:37 pm
Forum: RTL-SDR Discussion
Topic: mute on transmit
Replies: 4
Views: 995

Re: mute on transmit

How much power do you transmitt and on which bands do you have problems? Have you considered that it is direct RF getting directly into your setup somehwere after you muted the audio that is generating the hiss? I know in todays totally solid state envrionment it is an old fashioned advise, but have...
by snn47
Mon Sep 02, 2019 5:42 pm
Forum: Antennas
Topic: Antenna Element Wire Gauge Effect
Replies: 4
Views: 2176

antenna resistive loss vs. diameter vs. bandwidth (capacitance)

I assume I understand what you are asking now. You are asking about the effect of conductor diameter onto bandwidth and antenna efficiency. Those are all related to antenna efficiency and bandwith but different effects are involved. It is always a tradeoff what is sensible to do for a given frequenc...
by snn47
Sat Aug 31, 2019 1:36 pm
Forum: Antennas
Topic: Antenna Element Wire Gauge Effect
Replies: 4
Views: 2176

Re: Antenna Element Wire Gauge Effect

which frequency range, how high AGL and how long (inm) is long for you?
Why .would you want to connect a wire to your PC?
by snn47
Mon Aug 26, 2019 6:26 pm
Forum: RTL-SDR Discussion
Topic: Showing wave form on an oscilloscope.
Replies: 5
Views: 2461

Re: Showing wave form on an oscilloscope.

Even If your oscilloscope is fast enough to display strong signals at 137 MHz, oscilloscope are quite insensitive compared to the frontend in spectrum analyzer. The easy solution would be to use a receiver with sufficient bandwidth and sensitivity and connect an IF-output to your oscilloscope.
by snn47
Sun Aug 25, 2019 6:48 pm
Forum: Antennas
Topic: Adjustable Matching Transformer Exist ??
Replies: 4
Views: 1984

Re: Adjustable Matching Transformer Exist ??

antenna tuner also can be used as pre-selector tunable bandbass filter
It depends on the design of the matching network if it can be used as pre-selector tunable bandbass filter, e.g a Pi-design is a Low pass filter.
by snn47
Sat Aug 24, 2019 7:07 pm
Forum: Antennas
Topic: Adjustable Matching Transformer Exist ??
Replies: 4
Views: 1984

Re: Adjustable Matching Transformer Exist ??

Yes impedance matching circuit/transformer exist. The problem is you have to place such a device directly between the antenna and the transmission line e.g. coax cable to work. Then you have to tune it to the frequency you want to operate on, and again after you change the frequency. This requires s...
by snn47
Sat Aug 24, 2019 6:53 pm
Forum: Antennas
Topic: antenna related information and guidance for asking questions to improve chances for an answer
Replies: 6
Views: 6055

Re: guidance for asking antenna related questions improves chances for an answer -proposal for a sticky post

@ High SNR
Added your suggestions

@hotpaw and others
Are you proposing to add this information here or as separate post, e.g. Must read on antenna and transmission lines?
by snn47
Sat Aug 24, 2019 10:00 am
Forum: User Projects
Topic: USB HUB Recommendation!!!
Replies: 1
Views: 1971

Re: USB HUB Recommendation!!!

Even if an USB Hubs is shielded it won't help if you use poorly shielded USB cableand if you don't have a consistant shielding from connector to cable to connector, for all devises connected together. In comercial receiver metall boxes are used, which are either soldered cover or have additional con...
by snn47
Sat Aug 24, 2019 9:41 am
Forum: Antennas
Topic: antenna related information and guidance for asking questions to improve chances for an answer
Replies: 6
Views: 6055

antenna related information and guidance for asking questions to improve chances for an answer

Rev.2 2019.Oct.09 Rev.1 2019.Aug.24 I propose to make a sticky post that provides guidance about how to formulate antenna related questions. This makes it easier to no what information is needed, without having to consult a crystal ball if you are lucky enough to have a funtional one. This makes it...