Both the Healing and the Radiolette work exceedingly well. What model Healing do you have and are the valves actually right against the speaker magnet ?

In the 503B there is a gap of 10mm between the valves and the speaker magnet.

Any chance a photo of your set would be possible ?

I am just wondering if the magnet itself may be weak and the presence of the valve may be upsetting the performance of the speaker. Just remember these old sets had Field Coils because the magnets of that day were not as strong. Tell me if I am wrong . but a simple shield should fix the problem.

A magnetic field can certainly alter an electron beam, a magnetic deflection CRT is a classic example.
There is no magnetic field in the valve, only electrostatic and I cannot see any way this can affect the speaker magnet.
Harold

Photo uploaded to Post 12.

Most of my data books date into the heyday of valve radio, Its a case of which one in 24' of shelving containing only the radio books, was it.

I doubt it matters what the material is in the plate, if there is enough magnetic flux it will win. Even a magnet placed close to a fluorescent tube will have an effect.

Most of my data books date into the heyday of valve radio

Same here.

Much of the info in these is either no longer seems to be understood, that starts at Radio wave propagation, especially with Mobile & NBN towers, the construction of discrete parts, and radio technology in general.

We see a classic example of this in the Vintage Radio section of a particular Magazine, where a certain person of high educational position does not understand the principals restoration to as close to original as is practical without introducing modifications unless essential in the interest of safety, or valve technology in general.

One worries as to what students are being taught by him and I doubt that he is a one off and its across many fields.

Simplex, it IS a 503B. See picture in my recent post General Discission / Battery Valve Power Supply reprise.

In my set, the undistorted output power and the IM distortion BOTH improve noticeably when the chassis is released from the speaker and pulled back.

No field coils in battery radios, not in the 1950s at any rate!

Harold, I assume you are joking! That's what we are talking about, a magnetic field from the speaker that shouldn't be there.....

I doubt very much that a conventional tinplate shield around the valve would have any effect, not at less than 10mm, anyway.

Have you ever moved a magnet near one of those green VFD displays (like you see on cash registers and VCRs) and seen how much the magnet degrades it? Almost exactly the same technology, same voltages.

VFDs are interesting. Japanese started making these in 1960s using plant that used to make battery valves. They are about the only bit of thermionic technology that's still around!

Oh, on the subject of the Healing 503B (and indeed other Healing portables):

Anyone care to hazard a guess as to the IF frequency of these radios? No fair peeking at the schematic!

Now you know the reason for those huge old-fashioned-looking IF cans.....

Harold, I assume you are joking! That's what we are talking about, a magnetic field from the speaker that shouldn't be there.....

My reply was to answer Carls post about the valve affecting the speaker magnet, rather than the other way around.

Apologies to all if I didn't make this clear. I completely agree that the magnet can affect the valve operation, I cannot see how any field from the valve can affect the speaker magnet.

Harold

a certain person of high educational position does not understand the principals restoration to as close to original as is practical without introducing modifications unless essential

Yet, in his latest article on a battery powered set he has left the electros and wax Ducons in place.

I like the articles but I do question his methods.

180kHz IF.

The 503B is one of the best performing battery portables I have and over the years has been taken on a number of camping trips to some pretty poor signal locations.

Speaker magnets near valves not withstanding.

Yeah I wasn't actually saying there could be a field coming from the Valve. I was just suggesting that maybe the magnet in the speaker was weak and the presence of the valve may be upsetting it . I am probably wrong but you don't know until you ask. As for people not regarding modern safety standards I shake my head when I see old radios restored but still with the figure eight cords. I have bought a few and the first thing I do is change them.

I wasn't arguing about the RF performance of the 503B. 180kHz IF and an RF stage pretty much settles that, it's just about ideal for a broadcast-band-only receiver.

Just that the sound quality isn't quite as good as other radios in my collection with similar speakers and electronics. It's not much better than my AWA 405P, and it should be. So I was wondering why, and I guess by pulling the chassis back from the speaker I've found the reason.

In Ch 35 of Radiotron Designer's Handbook 4th Ed there is a section on problems with the local oscillator, and in that a section for battery radios. This warns that in "laying out any receiver that the characteristics of valves can be seriously affected by the presence of a magnetic field. All valves are likely to fall off in performance if placed too close to a loud speaker, and oscillator grid current can be reduced in this way".

Radio and Television Engineers Reference Book in Ch 23 on valves, heading Operating Conditions, Mounting says that "The characteristics of valves placed in a strong magnetic field may be affected : miniature 1.4V valves, in particular, should not be mounted in close proximity to loudspeaker magnets."

Nickel and nickel plated components are common in valves, and both metals are ferromagnetic so maybe these are affected by the magnetic field by being pulled out of shape, or affected by the magnetic field of the field magnet as the speaker vibrates in operation. Then there no doubt could be a direct affect on the electrons.

The type of permanent magnet speaker with a flat back and annular permanent magnet shown in the above photo is said to have the lowest efficiency (magnetic flux from the magnet actually getting into the voice coil gap), and have the most field leakage. (The lowest leakage, most efficient are said to be those with a rounded back.)