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Bob, Some of us are not bean counters, but want to know now things work and don’t work, and give them some love too. You can go back to Stephah Gray in about 1750 who found out electric fluid moves

Hi Don, I followed this case more or less since Emanuele posted it, so be kind if I misunderstood anything about. I remember that Emanuele complained about a complete loss of sensitivity in the lower

Oops! In my note number 2 I should have said "... except for C62." Thanks for catching that, Don. 73, Maynard W6PAP

Tom, as you are able to measure it, what is the ripple across C48 and across C44 when the bass switch is “IN” ? What is not normal is to have more “hum” when the bass switch is “OUT”

I rebuilt my SX-28a about 10 years ago including pulling the RF deck out etc. I have never experienced a hum with the bass switch in either position. [email protected]> wrote:

It seems that the way to look at this switch is that in one position the plate load is provided by the choke while in the other the load is switched to R37, and as an aside the choke gets shorted ?

I feel that the guy that had the original post many moons ago was correct. Get rid of it. The job of any good bench technician is to be able to recognize a dog and move on, not beat a $40 radio to

Maynard , I’m gonna mess-up your fine writing! .. Sorry. If there is stray coupling transferring signals at the top end of each band, we might expect that it would see lower loss at the higher

Richard, When the bass switch is “in” it boosts the bass. Going by the schematic it shows that it shorts the choke / cap. Audibly it definitely boosts the bass, I need to confirm the wiring of the

I unscrewed CH2 from the chassis and let it float, no change. Sent: Saturday, February 15, 2025 8:07 PM To: [email protected] Subject: Re: [HallicraftersRadios] SX-28A Hum Ok, tried two

Richard, yes it is hard to describe what is actually a drawing on paper. Perhaps you don’t have anything to copy what you see. Here, I am using

Hi, Don, If there is stray coupling transferring signals at the top end of each band, we might expect that it would see lower loss at the higher frequencies, and that is what is happening, it seems.

Ok, tried two different 6V6’s, no change. On the plates of the 6V6’s there is 6.8Vrms of 120hz ripple. If I remove the 6v6’s it drops to 4.7Vrms and the hum is no longer audible (as expected).

I have not read all the posts on this thread so may be repeating something. Tom, I do not have an SX-28, In normal operation what does the bass switch do? Does the bass increase or decrease when the

We were writing at the same time and obviously (good word) have the same questions. -- Richard Knoppow Los Angeles WB6KBL SKCC 19998

This is getting difficult to talk about. The antenna stage, i.e. the circuit between the antenna and the RF grid, is virtually the same in both receivers. The plate circuit is not the same. In the

Maynard re “ So, in the S-85 schematic there is no coupling at all from the plate of V1 to the grid of V2.” Well??? Maybe So, in the S-85 schematic there is no obvious coupling at all from the

Greetings to the Group: I tried to take some photos using my digital microscope, but unless you want a close-up of a rivet in the band switch, the magnification is too high and the field of view is

Hi Jacques, I just received 1.5 cents from you. Your proposal may well be, but how do you explain the difference the switch setting makes? Sent: Saturday, February 15, 2025 5:57 PM To:

Tom I’m glad I have company on that. Because the switch makes the difference and is before the 6V6s, I tend to think it is up there. Perhaps put a sizable cap on each grid to see if the switch