¿ªÔÆÌåÓýI have a suspicion that Hallicrafters, seeking their necessary profits, sought to design the best receivers they could using the most economical parts available to them, which may have varied from time to time.? Sales, marketing, and supply chain may have driven engineering, except on certain high-end models which may have been the personal pets of the engineers. ? 73 ¨C Steve, KW4H ? From: <[email protected]> on behalf of Richard Knoppow <1oldlens1@...> ? Made me wonder too.? The 7H7 is a remote cut off tube similar to the 6SG7.? One would expect a sharp cut off tube as an FM limiter.? And how is it used as the AM detector? I am stuck with the galaxy phone as my computer.? It's hard to see schematics on it.? Hallicrafters used some odd tubes.? ? ? ? ? ? -------- Original message --------
From: don Root <drootofallevil@...> Date: 10/30/22 7:28 PM (GMT-08:00) Subject: Re: [HallicraftersRadios] SX-110 2nd IF Circuit Design ? Jacques ?and the gang Do you/we believe that an early version of the schematic was much the same as later versions BUT the old drawing was in error by calling the 7H7 a Limiter, when all the time it was an IF amp? don ? From: [email protected] [mailto:[email protected]] On Behalf Of Jacques_VE2JFE ? Hi all, ? There is no 6SC7 in the SX-42. The tubes used are (from the 89D257 latest schematic). ? 1st RF and 2nd RF: 6AG5 Local Oscillator & Mixer: 7F8 1st IF: 6SK7 2nd IF: 6SG7 3rd IF: 7H7 Limiter & AM detector: 7H7 Noise Limiter: 6H6 FM Discriminator: 6H6 BFO and S meter Amp: 7A4 Audio Inverter (phase splitter + driver): 6SL7 Audio Output: 2 x 6V6 ? 73, Jacques, VE2JFE in Montreal ? Scott, and ?Steve and the gang: I think Steve clarified a mistake re the sx-110 , but he listed IF tubes for others ?and never said anything about my comment on the sx-42 . he listed?? ¡°SX-42 (1947-50) 6SK7, 6SG7¡±? ?my? ?1996 Dachis ?book and my ?Osterman? book says ?6SK7,? 6SC7, 7H7 I also said ¡°Wonder if we have the same printing¡¡± ? Now I wonder if ? my? ?1996 Dachis ?book and my ?Osterman[ second edition]? books ?are wrong ??about the 42 ? For the 62 you mentioned ?,Osterman ?lists the same IF tubes as it lists for the 42, [6SK7,? 6SC7, 7H7] and also says the A version seems to be the same except for the speaker impedance,, BUT Dachis says? 6SK7?6SG7?6SG7? I guess I must be off-track, and/or cant read these details so maybe somebody else can check these books? Don VA3DRL |
