[Elecraft] Elecraft technology

[Bill Coleman]

On 12/26/03 12:58 PM, N2EY@aol.com at N2EY@aol.com wrote:

[Double-conversion superhet description deleted]
>
>This technique goes back to the 1950s and Collins' 75A series receivers and 
>the S-line. 

It occurs to me that part of this technology change may have been due to 
the rise of SSB over earlier AM technologies.

>Ah, you missed a step, I think.
>
>in 1979, we hams got the so-called "WARC bands"  - 30, 17 and 12 meters. The 
>methods described above worked fine for rigs covering just the ham bands 
>80/40/20/15/10, but many of them could not be easily modified to handle 
>the new 
>bands without lots of spurs. So the up-conversion tactic was used, and 
>general 
>coverage receive was a side benefit.

There were a number of WARC transceivers using the older dual-conversion 
technology at the time. The TS-130, 530 and 830 come to mind, as does the 
Ten-Tec Delta.

Seems like several forces arrived at the same time to drive manufacturers 
toward general-coverage design. In addition to the WARC bands, the FCC 
also decomissioned the LORAN A transmitters, which meant amatuers had 
full-power access to all of 160m. Also, there was the push beyond hybrid 
solid-state / tube rigs (like the TS-530) and more toward all-solid state 
designs. 

[ Phase Noise discussion deleted ]

>All of this is one reason why some folks swear their old receivers sound 
>"better" than the more modern Ikensu stuff. 

They certainly sound different. Most old receivers can't handle the 
dynamic range of modern rigs. Many generate a lot of internal noise by 
comparison. 

My K2 sounds a lot different than my Kenwood. Especially on 10m during 
the 10m contest! The phase noise and IMD that isn't really noticible 
otherwise stands out in that comparison.

>Exactly. Besides, it's not practical to make a really narrow filter for 70 
>MHz.

Collins got a head start with their mechanical filters years ago. Narrow 
filters for 70 MHz aren't impossible, just expensive.

>Ten Tec's ham-bands-only rigs had always used that approach. There's only 
>one 
>conversion between antenna and sharp filter in almost any of their rigs, 
>going back into the '70s. 

The Omni V stands in great contrast with it's predecessor, the Paragon. 
In going to general coverage from the earlier Corsair and Omni series, 
the Paragon receiver lost a lot of fine qualities.

>Strictly speaking, a K2 is dual conversion, but the second conversion is 
>just for the AGC.

Details, details....

Actually, that's part of the genius of the K2. Who would throw in an 
entire crystal, mixer and IF stage just for an AGC? Makes a darn fine 
AGC, though. Best one my ears have ever heard.




Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901