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C7 plates spacing.. -- Emanuele (IU1KNR). https://egirland.blogspot.com

And the Band Spread variable cap C5A is in minimum position (plates fully unmeshed) all this time ? 73, Jacques, VE2JFE in Montreal De : [email protected] <[email protected]>

Jacques that’s not fair, you are doing your own arithmetic. And much of what you say must be right, but nobody mentioned what C42 is doing. In my quick re evaluation after peaking at the manual,

Sorry: L3 has no core inside, as per schematic. About C7 I am reconsidering the idea: after all when at the top of the bands it is fully open.. so the dirt can interact only minimally... -- Emanuele

Does the rotor plates are positioned in the exact center of the stator ones, or not ?? Please take a picture ! 73, Jacques, VE2JFE in Montreal De : [email protected]

Emanuele, Fantastic pictures, but I do not believe that the C7A tuning cap can be at fault. Obviously the coil have too much inductance, so it’s core have to be moved OUT of the coil (to the top, or

Sorry, that is not true. Looking carefully I can see a thin deposit on the plates: The outer part of the plate looks cleaner as I passed my finger on it.. -- Emanuele (IU1KNR).

I think it's time to narrow? the investigation down and tackle one problem at a time. As the "v1 / V2 coupling" and the "not C62" problems are really intriguing but seem loosely related to the

Don, Richard: I do not agree. CH2 is listed as a 4Hy choke in the parts list, and the C43 across is a 5100pF (0.0051?F). Both form a parallel resonant circuit centered at 1114 Hz. So when they are

Hi again Tom, Maybe some will find the following approach brutal, but here is what I will try with that SX-28A. Solder-tack two pieces of wire from the 6V6 pins 5 to GND: connect GND where both C47

Jacques, maybe look at “scope” sweeps in here and some in just after posts I think. I didn’t get far, and misinterpreted scope face info. I have to copy then and add my own marks or I will get

Richard ,agree again Re “I am pretty sure the markings on the schematic are reversed. Agree again It seems to me the Bass switch also changes the gain of the stage by increasing the B+.” perhaps

TomOK, does R35 have any affect on the hum? Can you scope the terminals of CH2 when the Bass switch is in both positions?? You most likely will have to do either a differential measurement using

Yes, hum is present – at the same level – regardless of the AF gain position. It does not change with AF gain adjustment so the issue is after the AF gain pot. CH1 and CH2 are not near each other.

6SC7, sorry. Thanks for the input, yes more poking is needed. Hopefully later tody. Tom Sent: Sunday, February 16, 2025 12:08 AM To: [email protected] Subject: Re: [HallicraftersRadios]

The B+ goes to the plate of the first audio through R-37, when the Bass switch is in the IN position (as shown on the schematic) the choke is bypassed, the B+ to the plate through R-37, when the

Richard, we agree about the switch position labels on the schematic being reversed. Sent: Sunday, February 16, 2025 5:00 AM To: [email protected] Subject: Re: [HallicraftersRadios] SX-28A

I am curious about that switch. I would interpret IN as meaning the bass was boosted but the switch shows it the other way. Also the frequency response chart shows the bass boosted with switch "IN".

TomWhen R33, the audio gain control, is set for minimum volume, do you still hear the 120 cycle hum regardless of S10, the Bass IN / OUT switch position?? If you still hear hum then the source of the

Do you mean the 6SA7 or 6SC7? The 6SC7 is the dual triode that acts as the first audio and phase splitter. Pulling that leaves the 6V6's active. CH-2, the bass boost resonator, connects from the grid