Search found 318 matches

by Mike2459
Tue Jul 16, 2019 4:39 pm
Forum: SDR Antennas
Topic: A FOOLPROOF ANTENNA SWITCH
Replies: 30
Views: 14109

Re: A FOOLPROOF ANTENNA SWITCH

glovisol: This would certainly help solve the contact resistance problem. However I see the need for two DC blocks (one at Rx In, the second at Rx Out) to prevent the relay contact biasing current from being shunted to ground by any upstream or downstream shunt inductors or RF transformers in the an...
by Mike2459
Tue Jul 16, 2019 9:42 am
Forum: SDRuno
Topic: AM Broadcast Stations on 22 MHz
Replies: 17
Views: 3853

Re: AM Broadcast Stations on 22 MHz

I have 22MHZ loaded with images at night from the AM BCB. I'm using the hi_z port. I was going to say use mw/fm notch filter. I just tried that after switching to the A port on the RSP2. That doesn't help a bit. Wondering why. That gonna be just great when good propagation returns.
by Mike2459
Tue Jul 16, 2019 8:40 am
Forum: SDR Antennas
Topic: A FOOLPROOF ANTENNA SWITCH
Replies: 30
Views: 14109

Re: A FOOLPROOF ANTENNA SWITCH

Hello Phil & govisol. Hope there are no hard feelings but in any event I had to chime in on this discussion. Hope you don't mind. So here goes. You wrote: "which are not dry, by the way, because they switch RF currents when diverting TX power away from the RSP into a load resistor" These are not the...
by Mike2459
Mon Jul 15, 2019 4:48 am
Forum: SDR Antennas
Topic: A FOOLPROOF ANTENNA SWITCH
Replies: 30
Views: 14109

Re: A FOOLPROOF ANTENNA SWITCH

After reading the reference material provide by Ian1951, IMO the title of this post should be changed to 'A Fool's Antenna Switch'. And yikes, hanging this switch from the SMA connector of the radio's plastic case sends chills up my spine.
by Mike2459
Mon Jul 15, 2019 2:18 am
Forum: Spectrum Analysis
Topic: Evaluating RF filters?
Replies: 19
Views: 4405

Re: Evaluating RF filters?

I talked to one guy who designs and sells RF filters, and he said he looked into this but gave up because the filter design was going to be so complex. After plugging some numbers into RF Filter Designer for a notch filter for the MW Band, I can see what he was referring to. Not a lot of wiggle roo...
by Mike2459
Mon Jul 15, 2019 1:11 am
Forum: Spectrum Analysis
Topic: Evaluating RF filters?
Replies: 19
Views: 4405

Re: Evaluating RF filters?

Here is the link to a description of RF Filter Design. At the bottom of that page is a link to the download section of the web site.

http://www.iowahills.com/9RFFiltersPage.html

Mike
by Mike2459
Mon Jul 15, 2019 12:24 am
Forum: Spectrum Analysis
Topic: Evaluating RF filters?
Replies: 19
Views: 4405

Re: Evaluating RF filters?

It's RF Filter Design and not Designer. Sorry about that. As to the sweep. My unit has an adjustable sweep from .1ms to >10Sec. For this I used .1ms but it's not critical for a spectrum display as long as it is not too slow. Just adjust it for the best display. Too view it on an O'scope the timing b...
by Mike2459
Sun Jul 14, 2019 6:10 pm
Forum: Spectrum Analysis
Topic: Evaluating RF filters?
Replies: 19
Views: 4405

Re: Evaluating RF filters?

Here is a scan of the filter in use. My local RF environment is no way near as challenging as that of LA!
The real world.JPG
The real world.JPG (95.25 KiB) Viewed 2529 times
by Mike2459
Sun Jul 14, 2019 5:17 pm
Forum: Spectrum Analysis
Topic: Evaluating RF filters?
Replies: 19
Views: 4405

Re: Evaluating RF filters?

Here is a scan of my homebuilt 3 pole (not 2 pole) elliptic filter. Had to set the RSP2 to maximum RF gain and disable IF agc and manually set it to a low level to keep receiver noise from masking the low level response while trying to avoid ADC OL. Used a program called RF Filter Designer to determ...