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Shadow meter question - Printable Version

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Shadow meter question - Diverted - 02-04-2015

Hi,

I have a Philco 37-670 with an inoperative shadow meter (the newer style). Not familiar with this meter; it's the first time I've dealt with one. Pretty cool! Anyway, here is what I know and have done so far. Any suggestions?

1. The meter coil is good. It measures out to about 1,450 ohms.
2. I removed the magnet from the coil assembly. I've read that they lose their magnetism. I tried to remagnetize it with a neodymium magnet and think I succeeded; it's now magnetized enough to pick up a small paper clip.
3. I reinstalled the magnet, etc. The shutter that swings back and forth is in good condition, moves freely.
4. With the radio on, I am getting about 215 volts on either side of the shadow meter coil. The voltage doesn't change much (a few volts) when I tune in and out of a strong station. The vane moves a touch, but barely enough to make much difference in the width of the shadow.

Any suggestions on what to try? Should I be seeing a greater variance in voltage in/out of stations? 

Thanks! Here's the schematic:

http://imgur.com/NozIIBg

RE: Shadow meter question - klondike98 - 02-04-2015

Sorry no experience with them. I suspect you have seen this but just in case you haven't, there is some shadow meter info on Philco Repair Bench.

RE: Shadow meter question - Steve Davis - 02-04-2015

Your shadowmeter may be just fine. It sounds like there isn't much change in the AVC voltage, you may just need to use a longer antenna or the radio may need an alignment.

Steve

RE: Shadow meter question - Diverted - 02-04-2015

(02-04-2015, 12:22 PM)Steve Davis Wrote:  Your shadowmeter may be just fine. It sounds like there isn't much change in the AVC voltage, you may just need to use a longer antenna or the radio may need an alignment.

Steve

I'm thinking that may be the case. Antenna is plenty long enough, but have not yet aligned the set. 
Hopefully the magnet has enough magnetism in it. 

RE: Shadow meter question - Diverted - 02-04-2015

(02-04-2015, 12:46 PM)Diverted Wrote:  
(02-04-2015, 12:22 PM)Steve Davis Wrote:  Your shadowmeter may be just fine. It sounds like there isn't much change in the AVC voltage, you may just need to use a longer antenna or the radio may need an alignment.

Steve

I'm thinking that may be the case. Antenna is plenty long enough, but have not yet aligned the set. 
Hopefully the magnet has enough magnetism in it. 
Looked at the alignment info, and it calls for the use of a variable condenser of about 350 mmfd in several of the steps. What is this? The alignment instructions seem amazingly complex in this set, and call for parts and procedures I've not seen before. Anyone here recently align this set? Thanks!

RE: Shadow meter question - codefox1 - 02-04-2015

Almost all old tube sets have variable capacitors (aka condensers.) An awful lot of 5 or 6 tube superhets use a two stage tuning capacitor, the larger (more plates) is as often as not 365 or so mmfd. So if you can srounge up one, you're probably good to go. I'd loosen up the padder (screw adjustment capacitor) of the scrounged part.

RE: Shadow meter question - klondike98 - 02-04-2015

If you don't have a junk set they aren't too expensive.