In m y experience, after considerable testing, the optimum voltage for our receivers is around 170 VDC.
I also move the screen lead from the center-tap of R22 and R23 to the "hot" end, which makes a big improvement. Doing tjis is, IMHO, especially important at much lower B+ levels.
Ken W7EKB
Sent via the Samsung Galaxy S21 5G, an AT&T 5G smartphone
-------- Original message --------
Date: 4/5/23 09:23 (GMT-08:00)
To:
Subject: Re: [ARC5] BC-453-B Power Supply
I have recapped my "Q5ers" and I power them on 90 volts B+ and 24 volts DC on heaters. All from batteries. The heaters eat up a pair of 7 AH slabs but a stack oh 9 volt batteries just keep going and going and going and no need for that rabbit. I tried them at 45 volts and they make the effort but performance dropped noticeably. Those screen dropping resistors would need to be changed. Another ham has operated from about 27 volts B+ with those dropping resistors removed. I have not been willing to make that modification. At 90 volts the current draw is about 15 mA - from memory. Too lazy to dig out my notes.
73,
Bill KU8H
Bark less - wag more
> On Apr 4, 2023, at 10:38 PM, Dennis Monticelli <[email protected]> wrote:
>
>
> If you elect to not restuff the cap pots, it is easy to re-cap the set. Install a solder lug using the threaded stud that mounts the pot. That's your ground. Then it's typically three small caps (most are 0.05) from the lug directly to the stiff wires you cut from the cap pot terminals.
>
> Yes, lower voltage than 250V works fairly well. My experience is to keep it at least 60V for decent gain and sure starting of the BFO. The lower in voltage you go the more you're going to want to short out one of the R's in the screen voltage divider to keep the gain from decreasing too much.
>
> FYI. My 453B pulls only10mA at 60V with new caps. I've run it off a stack of 9V batteries and they last a long time.
>
> Dennis AE6C
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