Here we go with a Brand Z 9-S-262
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
(01-18-2015, 01:07 AM)Arran Wrote: Whilst it seems like tube stuffing a chassis on brand Zs part having separate oscillator and mixer tubes is actually a meaningful improvement to a radio. Having separate tubes for the mixer/detector and local oscillator reduces noise and allows more stable operation at higher frequencies then a pentagrid converter like a 6A8 or a 6A7.
Acked, and agreed. Philco did their own cost-cutting, though, and from 1932 on it usually involved combining mixer and oscillator functions in one tube, poorly at first (the infamous autodyne circuit first used in the late versions of the 70 and 90, then the 51, 52, 15, 71, 91 and most infamously, the 19 and 89). The 6A7 was a big improvement over using a 36 tetrode. But, yes, separate mixer and oscillator is always better. So Brand Z gets points for that.
But I take away points for connecting a 6H6 as a single diode (both plates and both cathodes are connected together, making it a single diode). Again, a 6Q7G could have done the same job as separate 6H6G and 6F5G tubes did.
Oh well, a 9 tube radio sounds more impressive than an 8 toober, right?
--
Ron Ramirez
Ferdinand IN
Posts: 15,444
Threads: 539
Joined: Oct 2011
City: Jackson, NJ
Ron
What's wrong with single diode?
Oh....do you want separate AVC and Signal paths? Philco in 38-15 separated them at some point, before they had them together.
Does this really improve sound?
Posts: 4,639
Threads: 51
Joined: Sep 2008
City: Sandwick, BC, CA
(01-18-2015, 08:34 AM)Ron Ramirez Wrote: (01-18-2015, 01:07 AM)Arran Wrote: Whilst it seems like tube stuffing a chassis on brand Zs part having separate oscillator and mixer tubes is actually a meaningful improvement to a radio. Having separate tubes for the mixer/detector and local oscillator reduces noise and allows more stable operation at higher frequencies then a pentagrid converter like a 6A8 or a 6A7.
Acked, and agreed. Philco did their own cost-cutting, though, and from 1932 on it usually involved combining mixer and oscillator functions in one tube, poorly at first (the infamous autodyne circuit first used in the late versions of the 70 and 90, then the 51, 52, 15, 71, 91 and most infamously, the 19 and 89). The 6A7 was a big improvement over using a 36 tetrode. But, yes, separate mixer and oscillator is always better. So Brand Z gets points for that.
But I take away points for connecting a 6H6 as a single diode (both plates and both cathodes are connected together, making it a single diode). Again, a 6Q7G could have done the same job as separate 6H6G and 6F5G tubes did.
Oh well, a 9 tube radio sounds more impressive than an 8 toober, right? ![Icon_wink Icon_wink](https://philcoradio.com/phorum/images/smilies/icon_wink.gif)
Ron;
I always figured that Philco's use of autodyne circuitry was the company's attempt to circumvent RCA's patents, at least on their higher production models. The arrangement with an RCA licensee was that they would have to pay RCA so much in royalties per set they built, so less money going to RCA meant more money going to Philco. I've read about the non stop patent wars that went on in U.S courts for decades, and the rivalries and conflicts they created, and public enemy #1 was RCA since they held so many patents exclusively, so many manufacturers went out of their way to circumvent or work around them. Some are borderline idiotic, like the tube shield bases Philco use in their 1938 model sets, purposely designed to prevent the use of anything but G style octals being used, it seems like a childish and vindictive attempt to control what style tubes a Philco owner used as replacements.
In Canada, on the other hand, all the manufacturers were involved in a patent pool called "Canadian Radio Patents Ltd", no doubt that you have seen this posted in the back of some of your Canadian built Philcos. In exchange for the control of the patents from various companies they were issued shares in Canadian Radio Patents and could use whatever patents they wanted, they paid royalties to the patent pool, and the pool would pay them back in dividends. This is why you see things like Canadian Philcos with factory fitted RCA phono jacks, and Canadian RCA sets with 5Y4s, they could pretty much use whatever they thought best, it all worked out the same in the long run.
Regards
Arran
(This post was last modified: 01-18-2015, 11:30 PM by Arran.)
Users browsing this thread: 1 Guest(s)
|
Recent Posts
|
Cannot Adjust an IF Transformer’s cores
|
It works! I received the PCBs this morning in the mail, and put everything together. I reused the base from the original...jrblasde — 04:32 PM |
PT-6 antenna connections
|
I seem to have lost my way on this PT-6.
I see the antenna aerial transformer schematic - I’m reading pins 1 through ...bridkarl — 12:30 PM |
40-150 General questions
|
Good thing you're a good electrician ... the pictures show a lot of rewiring in your future! Take care and BE HEALTHY!...GarySP — 11:52 AM |
40-150 General questions
|
I think RobB has it right. It is a part number and looks like its stamped on the chassis and that wasn't something you ...klondike98 — 11:41 AM |
40-150 General questions
|
It's most likely a part number. Most of Philco part numbers are in that format. I looked at the parts list for this mode...RodB — 08:10 AM |
40-150 General questions
|
Hi Kevin,
No, I don't but I like your Quote about being a good electrician. The way I look at it is "The fact ...MrFixr55 — 08:06 AM |
Philco 38-7 Speaker
|
7K should be fine. While not a perfect match (This transformer is meant for 6V6 tubes), Antique Electronic Supply (AES)...MrFixr55 — 08:03 AM |
40-150 General questions
|
I discovered a stamp on the underside of the breadboard on my Philco 40-150. It is"56-1417' in black ink with numbe...Kevin_D — 07:14 AM |
Philco 38-7 Speaker
|
FYI the Impedance of the HR20 (the one I have) secondary of the audio transformer is 5 ohms. The 38-7XX speaker is suppo...tludka — 04:22 PM |
Philco 38-7 Speaker
|
Yeah, don't use the transformer currently on the H-20 (Dopf, I thought "H20, is that new technology, a speaker usin...MrFixr55 — 03:51 PM |
Who's Online
|
There are currently 2165 online users. [Complete List] » 1 Member(s) | 2164 Guest(s)
|
|
|
![>](https://philcoradio.com/phorum/images/bootbb/asb/right_arrow.png)
|