Posts: 1,287
Threads: 44
Joined: Nov 2017
City: Menlo Park
State, Province, Country: CA
Meanwhile, 10 KOhm pots arrived over the weekend, so I can begin construction of the IBAM circuitry. I did note the alternative Bias-balance adjustment, said to be a little easier to tweak, and wondered about implementing it. It was claimed that at least one design eliminated the risk of failure of bias supply, should one of the pots lose wiper contact. A couple of things put me off. First, I could not find a schematic, second, it was noted that the bias voltage range was limited, and not necessarily sufficient for all replacement 7591 valves.
Pondering a little more, it seems that with the addition of one extra resistor, one might be able to configure a fail-safe IBAM, but I want to sketch something out and run the numbers to be sure. I'll write up here if it looks like there is any progress on that.
Cheers
Ed
I don't hold with furniture that talks.
Messages In This Thread
RE: Fisher 500C restoration - by EdHolland - 05-29-2019, 11:10 AM
Users browsing this thread: 19 Guest(s)
|
|
Recent Posts
|
|
Shadow Meter Bulb
|
| Not sure if anyone has tried this but there are 6.3 volt miniature lamps in bayonet and screw-in base options available ...GarySP — 11:31 AM |
|
Shadow Meter Bulb
|
| Any 6.3 volt pilot light will work. I would use the brightest one I could find in my workroom. Be sure the dial is clean...RodB — 10:45 AM |
|
HiFi (Chifi) tube amp build - but my own design.
|
| Tim,
nice write up and thanks for sharing !!
Sincerely Richardradiorich — 02:47 AM |
|
HiFi (Chifi) tube amp build - but my own design.
|
| Well, this was a real "Hum-Dinger" :lol: ! This will be kinda long, but hopefully it will help others having t...TV MAN — 01:55 AM |
|
Shadow Meter Bulb
|
| Phorum members, I am trying to find the bulb # for PHILCO Shadow Meter part number 45-2180 that is from a 37-640 chassis...georgetownjohn — 06:53 PM |
|
Philco 41-608 changer coupler
|
| 3D-printing...short of machining, of course.
Or molding.morzh — 05:20 PM |
|
Philco 41-608 changer coupler
|
| Thanks, Morzh.
That solves the issue of the rubber pieces. Now, I need to find a way to replicate the pot metal piec...alangard — 05:07 PM |
|
12' Philco
|
| If it is 12', either Kareem or Andre would have to jump pretty high to look at the front panel.
Kareem would have an e...morzh — 01:48 PM |
|
12' Philco
|
| And here's a story about the tires on the truck. Same "no-stoop" guy must have installed these! Take care a...GarySP — 01:17 PM |
|
Hickok AC51 tube tester
|
| I think they have only shown the secondaries of the transformer.
Two of them feed the rectifiers' filaments.morzh — 12:58 PM |
|
Who's Online
|
There are currently 8054 online users. [Complete List]
» 1 Member(s) | 8053 Guest(s)
|
|
|
|
 
|
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
