Difference between 41-295 and 41-300 - Printable Version
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Difference between 41-295 and 41-300 - hyounce - 11-28-2010
Apparently, the only difference between the Philco 41-295 and the 41-300 is an extra tube was added to the -300 AVC section. I'm wondering if that modification would actually be noticeable in any comparison of the two. Anyone been in the position of being able to compare the two, side by side? I'm considering punching the chassis of my -295 and adding a tube if it makes any real difference. Comments....
Henry
Re: Difference between 41-295 and 41-300 - Ron Ramirez - 11-28-2010
Don't bother, adding a 7A6 will not make any difference in the operation of your radio; other than a slightly higher drain on your set's power transformer from the extra filament current drawn by the 7A6.
The 2nd detector and AVC functions were handled by the 7A6 in the 41-300, while the 7C6 acted only as the first audio amplifier. But since the 7C6 has two diode plates already built into it, these were used in the 41-295 for the second detector and AVC.
The 7A6 was not needed, and was (in my opinion) an example of padding the tube count for no good reason.
Of course there were manufacturers who padded their tube counts far worse than this. But the bottom line is - leave your 41-295 as is.
Re: Difference between 41-295 and 41-300 - hyounce - 11-28-2010
Thanks, Ron
I appreciate your help with these kinds of things. While I'm at it, I have another question about the twin 370 pfd caps in the push button assembly. As you know, the cap itself is a rather strange affair, physically, but electronically appears to be pretty straight forward. I noticed, last night, that after an hour or so of listening the push buttons had all drifted and had to be re-adjusted for optimum operation. As a result, I decided to replace them with a couple silver mica units, hoping to stabilize the situation. The replacements didn't work at all, so I returned the set to it's original configuration. Strangely enough, the original cap configuration then failed to work.
I started taking some voltages measurements, and was surprised when the receiver snapped into normal operation the first time I touched the B+ line with my probe. A small spark when I made contact. The unit is working great, now, with the exception that I am hearing what sounds like very brief, instantaneous, bit of static, every now and then, that also interrupts the signal. Other radios in the house aren't affected this way, so You can assume that the problem is restricted this receiver. All electrolytics have been replaced with appropriate 500v units, and the B+ lines all appear to be firmly soldered. No changes when all tubes are tapped sharply and wiggled in their sockets. Any ideas?
Henry
Re: Difference between 41-295 and 41-300 - mgutierres - 11-30-2010
I was wondering the same thing, about the additional tube in the 300, so thanks, Ron for clearing that up. After properly aligning my 295, it really pulls in distant stations at night, loud and clear. It's an amazing radio.
Henry, is it possible that the trouble is in the bandswitch? Have you tried jiggling it a bit to see how it affects the radio? The linkage is usually as sloppy as a 3-on-the-tree gear shifter, and the detent cam gets loose over time, causing inconsistent contact between the bands.
Re: Difference between 41-295 and 41-300 - hyounce - 12-02-2010
Thanks, Ron for tolerating my ignorance, and for all of your good advice. I love tinkering with these old radios, but sometimes I think I should go back to flying jets, and other activities where I'm better qualified.
As to the matter at hand, I'm happy to report that my 295 appears to be functioning as it should. The annoying random crackling ended up being a single strand of a multi-strand B+ lead arcing over to a ground lug. Naturally, the arcing was occurring in an area that was pretty much hidden from view. Ended up finding it by turning the chassis upside down, in a dark room, where I was able to finally catch a glimpse of the sparking. No real electronics theory, here, but then I warned you that I'm a little short in that area.
Tried to align the set, yesterday, and am quite pleased with the results. I am using a Lodestar Signal Generator/Counter that doesn't have a provision to vary the output, so it tended to overdrive the system. Ended up adjusting the "Compensators" using a very weak station. The procedure that required using a loop on the generator, worked fine.
I live in the mountains, east of San Diego, where the AM reception isn't the best, so I'm looking for a better antenna system. Most of the stations I'm interested in are West or North of my location. The loop antenna originally supplied by Philco works pretty well, but needs to be rotated 90 degrees when I want to improve the reception from the North, and that, of course, isn't very convenient with present antenna location. Considering building a longwire antenna that will fit into my attic. The attic is "L" shaped, and will accommodate two 50' legs, oriented at right angles. Not sure if that particular configuration will be at all directional. May have to resort to one of the commercial amplified loop devices to solve my problem. Of course,there is a constant problem with stations on the Mexican side of the border over-riding some of the stations I'm interested in receiving. Are there systems available that are capable of effectively filtering or separation out some of those stations?
Re: Difference between 41-295 and 41-300 - mgutierres - 12-18-2010
Probably one of the best AM loop antennas out there is the Kiwa Pocket Loop (http://www.kiwa.com/pktloop.html). It's kinda spendy, but it's based on its big (and long since discontinued) brother air loop which I've owned for 15 years, and performs miracles both in receiving as well as nulling unwanted adjacent signals. With the proper impedance matching, I'm sure it would work wonders on your 41-295.
You also might try finding the loop from a 1940 model Philco console, which looks something like a cardboard-covered muffler. It works extremely well, and because it's much more narrow than the 295 loop, allows a nearly 170 degree turning angle from the back of the cabinet.
Good luck!
Mike