Search found 140 matches

by ON5HB
Fri Jul 26, 2019 4:28 pm
Forum: SDR Antennas
Topic: "Low Noise" Vertical Antennas for Receiving
Replies: 12
Views: 9566

Re: "Low Noise" Vertical Antennas for Receiving

Small capacitive antennas are called Mini-Whip they work well at very low frequencies, it all depends on the length of the whip. As for reflections, I do not measure it, I have a tuner for transmitting that solves mis-matches. For reception it doesn't matter much if there is a mismatch, the RSP rece...
by ON5HB
Fri Jul 26, 2019 11:44 am
Forum: New Users' experiences
Topic: Best antenna no good signals?
Replies: 21
Views: 11618

Re: Best antenna no good signals?

Yeah, that antenna is also called a dipole :lol: Specs seem to be: coaxial cable: 6m Wire : 6mx2 Antenna oscillator: 16.2m Balun 9:1 Kind of a weird combination. For listening not much is needed, just 2 pieces of wire (the longer the better) and a transmission-line (typical called coax or twin-line)...
by ON5HB
Fri Jul 26, 2019 11:31 am
Forum: SDR Antennas
Topic: "Low Noise" Vertical Antennas for Receiving
Replies: 12
Views: 9566

Re: "Low Noise" Vertical Antennas for Receiving

I agree with you Bas. Common mode current on the outside shield of a coaxial cable can be a problem but can be remedied with ferrites, isolation transformers and proper grounding. I think the other reason for not using coax in this design is to keep the impedance high on the primary of the transfor...
by ON5HB
Sun Jul 21, 2019 4:08 pm
Forum: General
Topic: Always 125 MHZ Offset!
Replies: 6
Views: 2532

Re: Always 125 MHZ Offset!

I could be wrong, but look for this screen and set it to 0.000 or remove the entry, see what happens:

Image
by ON5HB
Sun Jul 21, 2019 4:01 pm
Forum: SDR Antennas
Topic: "Low Noise" Vertical Antennas for Receiving
Replies: 12
Views: 9566

Re: "Low Noise" Vertical Antennas for Receiving

Hi Bill, He makes a very interesting point, but sadly a wrong remark: While studying active whip intercepts some time ago I discovered, much to my amazement, that long coax (50 feet) lead often degrades 2 nd order intercepts of active whip antennas by 20 dB or more and degrades 3 rd order intercepts...
by ON5HB
Sat Jul 20, 2019 8:39 pm
Forum: SDR Antennas
Topic: Receive Antenna & Impedance "Matching"
Replies: 114
Views: 41333

Re: Receive Antenna & Impedance "Matching"

Well you say the same as I but in more detail. But I do not agree with 1 point, and that is the noise-floor. WSPR will go under the noise (whatever DBM it is) by -33. Mostly the noise on the band is pretty high, so most receivers have no problem capturing it. In short....WSPR goes below noise by 33d...
by ON5HB
Sat Jul 20, 2019 8:27 pm
Forum: General
Topic: AM and FM Band Reject Filters
Replies: 5
Views: 2303

Re: AM and FM Band Reject Filters

I have used filters and attenuators before, all the time mixing started on big signals. Ending up with AM stations as high at 40m....no joke. Checkout my websdr: http://heppen.be:8091 There are NO AM stations repeating, not a single one as far as I know. That is due to the up-conversion. Everything ...
by ON5HB
Sat Jul 20, 2019 5:53 pm
Forum: Spectrum Analysis
Topic: Spike in Center??
Replies: 1
Views: 3134

Re: Spike in Center??

Change the IF-type.
Normally we use Zero-IF, but spikes can arise, if you have a problem, try other IF.
by ON5HB
Sat Jul 20, 2019 5:15 pm
Forum: SDR Antennas
Topic: Receive Antenna & Impedance "Matching"
Replies: 114
Views: 41333

Re: Receive Antenna & Impedance "Matching"

However, if my input can be worth 2 cents, please understand that, among the RSP's the RSP-1A is not the best choice for the activity you are doing. The RSP2 or (better) the RSPduo with their HI Z imputs exhibit a tested noise figure that is from 6 to 9 dB better in HF than that of the RSP-1A with ...
by ON5HB
Sat Jul 20, 2019 4:55 pm
Forum: SDRplay related
Topic: SDRplay transceiver?
Replies: 4
Views: 2388

Re: SDRplay transceiver?

Hi John,

It will be too expensive, as for just 1200 euro/dollar you can get the Icom7300 and does everything up to 70MHz.
I doubt you can beat that.

I have looked at Anan and the price blew me out of the pond. Just too expensive.
They all are and they do not offer much over the 7300.