[AMRadio] When talking about AM power


Larry Szendrei ne1s at securespeed.us
Sat Oct 10 09:41:12 EDT 2015


On 10/10/15 6:14 AM, Rob Atkinson wrote:
> About the only thing that would be nice about SDR is the fish finder.
There's other advantages as well, such as continuously variable receive 
bandwidth. So you can set the bandwidth so that the interfering signal 
is just outside of the bandpass, and enjoy the maximum possible 
bandwidth up to that point. Of course, like any other receiver you can 
place the bandpass asymmetrically around the carrier to best eliminate 
adjacent channel interference. In a lot of the software you also have a 
synchronous AM detector option.
>
> But for me the cons outweigh the pros:
>
> Have to have a computer.
> Have to "boot up" the rig
> Forget fixing anything if it breaks.  Throw away the PC card or maybe
> the whole thing and get another one.  Or "send it in to the shop."
Not going to argue with that.
>
> Whenever I hear a ham say "The rig is out for repairs" I think how
> sad.  I am trying to not be one of those type hams.
Me, too!
>
> Does anyone really know how one of those rigs works?  Can I point to a
> cap or resistor and ask what is that there for and get an answer?  Is
> there a schematic even?
Some of the SDR receivers, like the Softrocks, are really quite simple 
in concept, at least as far as that particular hardware is concerned, up 
to the computer sound card input jack. Of course, if you insist on 
understanding how the computer hardware and software work to any detail, 
that's another matter.
>
> The cost.  $3500 !!! at least for that Anan thing, a little box with
> an on/off switch.  Does anyone think that 3500 dollar rig will be
> running in 40 years?  I guess it doesn't matter for me because I'll be
> SK most likely but 3500 can buy some nice antenna improvements that
> won't go out of date.  I work some piss weak guys with SDRs and I wish
> they had spent the money on a higher antenna, hi.
The Softrock kits are very reasonable. My first one was the 
simplest/cheapest one, built for a "single frequency" of 455KHz. I 
hooked it up to my SX-28 1st IF can through a JFET source follower, and 
if you operate the SX-28 in the widest selectivity position you can see 
about 20KHz of spectrum around the frequency to which the SX-28 is 
tuned. It cost less than $30 delivered to my door. And it gives me the 
choice of envelope or synchronous detectors for AM, and excellent SSB 
and CW detectors. Or you can just use your SX-28 (or other favorite 
receiver) in it's entirety for receiving, and use the SDR just for the 
spectrum display, if you wish.

I recently completed the Softrock Ensemble II receiver kit, which gives 
you a general coverage receiver from 1.8 - 30 MHz, with an antenna input 
so no other hardware is needed besides it, the computer, and antenna. 
This one cost me less than $70 including shipping, and it also works 
extremely well. I have a transceiver kit waiting to complete that was 
given to me, partially assembled, but since it only will put out around 
2W PEP, it will require a couple stages of "shoes." None will ever 
replace all the homebrew and classic gear at NE1S, but it's all really 
fun to play with.

This stuff is considered "old" technology now, though.The present trend 
is to "suck in" huge swaths of spectrum, digitize it all with a very 
fast DAC, and then have a powerful computer process it all. But that's 
pretty expensive, and for what most of us are interested in, seems 
unnecessary and wasteful.
>
> And the software fee.  If you get a Flex Radio you have to pay a
> regular maintenance fee.  What do they think this is, the iPhone
> (which I think is also for suckers).
Can't speak to the Flexes, but all the SDR software I've used (I've 
played with 4 different programs) has been free.
>
> The whole thing with computers and software is a red alert.   How long
> before an OS update, or a new driver, or some other issue comes up and
> the user is plunged into incompatibility hell looking for dependencies
> or decoding gibberish from some computer geek because the rig won't
> work.  Or the computer craps out and has to be replaced.  I just want
> to fire everything up and have a QSO.   For now having a nice spectrum
> display isn't worth the hassle, time and cost.
Yeah, but if you're going to use a computer anyway for non-ham stuff 
you'll eventually be dealing with that regardless,

73,
-Larry/NE1S

...who is not connected with the Softrock folks in any way except for 
being a (very) satisfied customer.


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