Solar Eclipse Data Showing Propagation Enhancement on the Lower HF Bands

Solar eclipse data shows interesting enhancement of my signals on 160 M (1.8 MHz) during the event. Similar data for another station is shown for 80 M band (3.5 MHz) also.

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“Z-Substitution” Method for Measuring UNUN Loss Into Real-World Load Impedances

Often one sees characterization and loss measurement of UNUNs using an SWR measurement of the UNUN when terminated in it’s transformation resistance, or with the “back-to-back” 2-x-Loss method.  Each method reveals something about some quality of the UNUN, but neither method tell us much about how much power the UNUN will deliver to the actual antenna.
unun-2In this article I will show a simple method of measuring actual UNUN losses into the actual load impedances that the UNUN will see in service.
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Classic W8JI Limited Space Antennas Article

Excellent technical article regarding limited space antennas:

Cap Hat Dipole

Limited Space Antennas

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We Don’t Need No Stinkin’ Sweep Generator …

… or any signal generator for that matter in order to align the IF section, including the notorious crystal filter and phasing circuits, of Vintage Receivers like the Hammarlund HQ145 and HQ129X.  It takes about a half hour once you get used to it, perhaps an hour or so the first time.  I’ve aligned my Hammarlunds with this procedure and found the units to be very close to factory spec as measured with standard lab equipment.

A layout diagram, such as the one for the HQ145 below, is useful ===>

hq145toplayout-1
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Turning the Hammarlund HQ145 into a Sweet, Sensitive, and Stable Ham Receiver

In this article we will look at a few of the big deficiencies of the Hammarlund HQ145 general coverage shortwave receiver, and put in some fixes.  CW/SSB reception with AGC and S-Meter, stability issues, bandspread, and sensitivity on the high band will be addressed.

Once modified, the HQ145 turns out to be a very nice ham and general coverage receiver all the way up through 10 M.  It’s like my wife: attractive, capable, and a pleasure to be with.  Or, it could be said Sweet, Sensitive, and Stable!

hammarlund-hq145-2

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Some Early Tubes and Circuits

Some early tubes and radio circuits from Radio News and BELL Telephone Laboratories.

searlytubes1926 1926_Radio-News__tubes-and-there-uses

higheffpa_1928_articlecover1936_BELL_Labs__high-efficiency-power-amp-for-modulating

fm_receiver  1940_Radio_News__design-notes-on-a-fm-receptor

 

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Classic Collection of Early James Millen

Here is a collection of some of James Millen’s early work in radio communication techniques.

radio-design-guide-1935-cover

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