Search found 33 matches

by vk3alb
Fri Feb 08, 2019 8:11 pm
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 6944

Re: Extending the range of a Discone antenna down to 3.6 MHz

Thank you both. An excellent experiment.
by vk3alb
Fri Feb 08, 2019 12:45 pm
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 6944

Re: Extending the range of a Discone antenna down to 3.6 MHz

Hi Glovisol, Yes it seemed to me that the electrical earth may be acting as an antenna for things other than interesting radio signals. I have seen noise carried by mains wiring cause significant noise on HF. Normal noise reduction techniques using ferrite cores applied to the wiring brought a great...
by vk3alb
Thu Feb 07, 2019 7:54 pm
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 6944

Re: Extending the range of a Discone antenna down to 3.6 MHz

Here is the detailed report: 1) The antenna is mounted on a 1.8 m steel pole which goest through the roof and is mounted with two steel brackets to a wooden beam of the roof. There is an elecrical (not RF!)) ground tied to the pole which was wired ages ago and is connected to the general electrical...
by vk3alb
Mon Jan 21, 2019 8:55 pm
Forum: General
Topic: Your MFJ-1708B-T/R Switch Experiences
Replies: 4
Views: 1574

Re: Your MFJ-1708B-T/R Switch Experiences

Ruben_NB4R wrote: I don't know why the SDRPlay don't make this standard practice if it is so needed.
Ruben_NB4R


The RSP2pro comes in a metal box but also comes at a price. As has already been mentioned not everyone needs such heavy shielding.
by vk3alb
Wed Nov 14, 2018 8:22 pm
Forum: SDRplay related
Topic: Bias-t voltage
Replies: 5
Views: 2232

Re: Bias-t voltage

I think the reason for the 5V bias voltage is understandable.

As someone mentioned there are lower voltage circuits of the mini-whip https://www.g8jnj.net/activeantennas.htm
by vk3alb
Sun Nov 11, 2018 12:22 pm
Forum: SDR Antennas
Topic: A FOOLPROOF ANTENNA SWITCH
Replies: 10
Views: 4807

Re: A FOOLPROOF ANTENNA SWITCH

Hi All, Thanks for the comments and suggestions. It shows that even in a simple circuit there may be room for improvement. Here then is the revised circuit with bypass caps and back EMF diode across the relay coil. I was lazy this morning and left them out. Not surprised that I was caught. :) RX iso...
by vk3alb
Sun Nov 11, 2018 3:50 am
Forum: SDR Antennas
Topic: A FOOLPROOF ANTENNA SWITCH
Replies: 10
Views: 4807

Re: A FOOLPROOF ANTENNA SWITCH

Hi Roger,

Yes I see that now. In that case, as long as the PTT (SEND) line can sink at least 10mA it can connect directly to the base of Q2. Then, remove D1, R2, R3 and Q1.

Thanks for the feedback.
by vk3alb
Sat Nov 10, 2018 11:04 pm
Forum: SDR Antennas
Topic: A FOOLPROOF ANTENNA SWITCH
Replies: 10
Views: 4807

Re: A FOOLPROOF ANTENNA SWITCH

Thank you to Glovisol for his excellent and elegant circuit. As he says in his text there is a way to protect the receiver in case of failure of the 12 volt supply to the circuit. I think my version of his circuit was his intention. RX Isolator.png Consider the modifications of his circuit as shown ...
by vk3alb
Sat Oct 13, 2018 9:23 pm
Forum: SDRplay related
Topic: RSP1A - RF Damaged?
Replies: 5
Views: 2561

Re: RSP1A - RF Damaged?

Hi John,

How do you know it is damaged?
What tests have you carried out?
Most things are repairable - for a price.
If it really is damaged your first stop is to seek advice from SDRplay support
by vk3alb
Sun May 20, 2018 8:54 am
Forum: SDRplay related
Topic: HOW ABOUT A TRACKING GENERATOR?
Replies: 3
Views: 2034

Re: HOW ABOUT A TRACKING GENERATOR?

One of our group is working on a spectrum analyzer package for the SDRplay. He talks about the challenges of including a tracking generator.

viewtopic.php?f=12&t=3164

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