|Joined:||Tue, Jun 5th 2007, 14:11||Roles:||N/A||Moderates:||N/A|
|power loss in tuner ?||Jul 17th 2016, 00:37||3||239||on 18/7/16|
|questions about AM broadcast band images||Aug 24th 2015, 13:20||2||475||on 24/8/15|
|Use of old laptop power packs ?||Dec 28th 2014, 15:30||1||828||on 28/12/14|
|Strange RFI on 10 meters and 6 meters||Jun 19th 2014, 17:12||2||1,046||on 19/6/14|
|Two important functions missing in new radios ?||Feb 4th 2013, 15:16||5||1,726||on 28/2/13|
|QST mobile reader which does not suck?||piranha32||4 weeks, 2 days ago|
|I had no problems in the past viewing QST on my iMac, but the new PageSuite implementation is impossible to read. The resolution is bad - everything is fuzzy regardless of the magnification / zoom. When zooming, for just a second or so everything seems to be in focus, but then the image deteriorates again. I emailed the circulation group, but wonder if I'm doing something wrong. Any suggestions from others who use an iMac ? Thanks.|
|power loss in tuner ?||AB3FN||on 17/7/16|
|It seems obvious that some power loss will occur in an antenna tuner, and it also seems that many factors determine the loss, e.g. SWR, resistance in the inductor(s) and wiring, frequency, Q of components, etc. Although we could, hypothetically, use high quality instruments to measure the loss in any specific situation, how would the loss be calculated?
For example, assume that we know the frequency, component values, purely resistive losses of wiring, etc., how would we calculate the theoretical loss.
Given today's modern equipment, I doubt losses are high enough to worry about in most circumstances. But perhaps this matters more when running QRP, or when building miniature tuners or matching networks from scratch.
Thanks in advance for your comments, thoughts, guidance.
|Lightweight, small HF rig - used||Lfox368806||on 1/11/15|
|Suggest you look at the Yaesu FT-450. Its very compact and lightweight, but is a solid performer and has many features. Used ones are well under $600. The menu system is not too complex, although all radios have their idiosyncrasies.|
|questions about AM broadcast band images||AB3FN||on 24/8/15|
|I want to explore the spectrum below the AM broadcast band. The second IF in my late-model triple-conversion radio is 455 kHz, and I'm getting swamped with broadcast band images. E.g., an AM station broadcasting on x kHz has a powerful image at x-910 kHz. My radio is a modern one, but I live near a large metropolitan area with a lot of AM broadcasters.
Is this a common problem with modern radios? Any comments about specific brands / models? I've had marginal results with a home-brew filter - any suggestions about filters? Of course, I'm only interested in receiving, not transmitting.
Thanks in advance for your comments and suggestions.
|Use of old laptop power packs ?||AB3FN||on 28/12/14|
|Laptop power packs typically put out 16-18 VDC at a few amps. Is there any obvious problem with using several and putting the outputs in series to get higher voltages ? Is there adequate isolation between the 110 VAC input and the output ? Problems with regulation ? Has anybody done this ? Of course, depending on the specific power packs and the desired output, there might be a need to insert a series resistor or something else to reduce the voltage. Thanks in advance for your reply, insight, and suggestions.|