HAMMARLUND HQ-120-X
July 2005 - March 2006
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July, 2005: Hammarlund's First Medium-Priced Receivers
The Comet, Comet Pro and Super Comet Pro: ancestors of the famed Super Pro. The HQ-120-X, introduced in 1938 at $129.00; the HQ-129-X and HQ-140, -150, 160 and -180 were descendants; comparing the HQ-120-X and HQ-129-X; comparing the two HQ-120-X sets in my possession.
August, 2005: Decisions, Decisions, Decisions!
A closer look at the two HQ-120-X‘s preliminary to deciding which one to restore; KB4CVN/C6AMC‘s AM-auto-radio-to-AM-marine-band converter.
September, 2005: Radio Role Reversal
After more careful consideration, the radio originally acquired as a parts set becomes the project set; switching the front panel, knobs and cabinet; cleaning the knobs; cleaning and polishing the front panel; the required 30-odd capacitors ordered and received; reader suggestions:
"G-JO" hand cleaner works wonders on Bakelite cabinets; making silk screens for panel labels; another approach: print the labels on decal media; results of the "Radio Restorations" reader survey.
December, 2005: The HQ-120: Picking up Where We Left Off
Completing the recapping work, a two-day job; Hammarlund‘s stinginess with tie points; installing a reproduction line cord; the odd tube complement; radio silent on initial test except for motorboating at certain volume control positions; open spot found in volume control and control replaced; problem found in first audio stage; Collins Collectors Association AM Night.
January, 2006: More on the HQ-120 and on Receiver Evolution
Audio problem traced to hard-to-find B plus short causing "cooking of filter choke;" more on broadcast receiver evolution: the "three dialer" era and the first plug-in sets (a continuation of the historical article, The First Broadcast Receivers, in the November, 2005 issue of the RADIO HISTORY series)
February, 2006: HQ120 Restoration and Receiver Evolution Continued
Short disappears in "AVC" mode--supplying clue to a problem I had created for myself; choke no longer smolders but audio problem persists; more radio evolution: introduction of the superheterodyne, screen grid tubes, table models and the grand living room console, tombstones and cathedrals (a further continuation of , The First Broadcast Receivers, in the November, 2005 issue of the RADIO HISTORY series).
March, 2006: The HQ-120 Comes to Life
Filter choke replacement reveals that output transformer had been disconnected and poorly reconnected--some connections intermittently shorting; choke and transformer from what was now the parts radio installed as replacements; radio now receives signals, but operation continues intermittent; problem traced to shorted leads to grids of r.f. and mixer tubes; defective i.f. transformer discovered during realignment; replacement from parts set installed; normal operation restored.