Category: Tech – General and Classic

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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Classic G3TXQ Balun / Choke Article

Excellent technical reference article by Steve G3TXQ:

choke_impedances_g3txq

Amateur Radio (G3TXQ) – Common-mode chokes

The above chart presents the results of impedance measurements made on a variety of common-mode choke implementations across the frequency range 1MHz to 30MHz. Amateur frequency allocations are indicated approximately by the vertical grey bands. Continue reading Classic G3TXQ Balun / Choke Article

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Classic Amateur Radio (G3TXQ) – Cobweb Antenna

Excellent technical reference article by Steve G3TXQ:

G3TXQ-tn_cob9

During recent range testing of a hexbeam I needed a horizontally-polarised resonant antenna covering 20m thru 10m which could be assembled and disassembled quickly and easily. The cobweb antenna meets the requirement nicely – it comprises 5 parallel dipoles bent into a square shape and mounted on a support structure made of fibreglass poles.
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Classic Amateur Radio (G3TXQ) – G5RV Antenna

Excellent technical reference article by Steve G3TXQ:

Few antennas polarise opinion as much as the G5RV – it seems you either swear by it or swear at it! The purpose of this article is to present a few technical facts about the antenna and allow the reader to judge whether or not it might be useful for them.

G5RV Antenna

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