21-06-2020, 08:00 PM
(This post was last modified: 21-06-2020, 08:04 PM by Mike Watterson.)
Ah, the CN420A is a bit of an outlier. It might have a larger than average coil, like the ER N & N3 have a bigger coil.
It's the coil enclosed area that counts. The Q isn't quite as important on the these size range of MW & LW loops.
A MW big coil with a series loading inductance will outperform a small LW coil. Also unless the coils are at right angles the unused one is reducing the signal. The 5214 LW aerial is small. I'd expect the later idea of the switched in inductance on a big MW coil to work better.
Not all Ferrite coils are equal. Certainly most 16cm ferrite rods will outperform the regular attache style flat coils, I did say that in the last post. I had a scraped Sky Queen case. It was a wreck, but chassis was good, and amazingly a local auction bundle included a Sky Queen cabinet with perspex bits, speaker and aerial coil, but no chassis. I've used that coil for testing and it's better than many ferrite stick aerials.
You can't compare the sets loop aerials directly unless they use the same valves swapped and the same IFTs and the same batteries, maybe even manually set AGC line volts. The Vidor sets are built down to a price and were sold to sell batteries as were the Ever Ready from the K onwards, they do perform very well and most are basically the same chassis or design.
Also the there is a variation of performance even with one model. I'm not sure why you'd replace the frame aerial in a K with a ferrite Rod. I use a specifically built receiver or my spectrum analyser to compare various ferrite rod aerials and loop aerials. There is an amazing variation of what works best for the valve radios and semiconductor tuners with no built in aerial, but just the A and E socket. An interesting solution is to wind SCREENED Cat5 on a frame (or picture frame). On some sets leaving the screen floating on MW and earthing one end on LW works best. Each pair is treated as one wire. So 5 turns of Cat 5 is 5, 10 or 20 turns by parallel or series of the cores. Some sets need extra series inductance switched in on LW and some don't with all 4 pairs in series. Some need two sets of pairs in series - parallel for MW and all in series for LW. Some sets need the loop to be tuned. The AM/FM semiconductor tuners work best with about 4 turns on a large frame. No design of loop (size/inductance, tuned/untuned) will work even for all valve sets that need an external aerial. They seem to have optimised for an open wire, not a loop, and some sets maybe on 3m, others much longer.
The Model H is Ever Ready two valve TRF, like 1920s, using the B7G valves. It's got various aerial connection options according to the wire length and needs an aerial. I've not found a loop recipe for it yet. It works better than I thought it would.
The loop (and ferrite rod) and batteries is of course superior to any radio on mains and worst is mains radio with end fed wire.
It's the coil enclosed area that counts. The Q isn't quite as important on the these size range of MW & LW loops.
A MW big coil with a series loading inductance will outperform a small LW coil. Also unless the coils are at right angles the unused one is reducing the signal. The 5214 LW aerial is small. I'd expect the later idea of the switched in inductance on a big MW coil to work better.
Not all Ferrite coils are equal. Certainly most 16cm ferrite rods will outperform the regular attache style flat coils, I did say that in the last post. I had a scraped Sky Queen case. It was a wreck, but chassis was good, and amazingly a local auction bundle included a Sky Queen cabinet with perspex bits, speaker and aerial coil, but no chassis. I've used that coil for testing and it's better than many ferrite stick aerials.
You can't compare the sets loop aerials directly unless they use the same valves swapped and the same IFTs and the same batteries, maybe even manually set AGC line volts. The Vidor sets are built down to a price and were sold to sell batteries as were the Ever Ready from the K onwards, they do perform very well and most are basically the same chassis or design.
Also the there is a variation of performance even with one model. I'm not sure why you'd replace the frame aerial in a K with a ferrite Rod. I use a specifically built receiver or my spectrum analyser to compare various ferrite rod aerials and loop aerials. There is an amazing variation of what works best for the valve radios and semiconductor tuners with no built in aerial, but just the A and E socket. An interesting solution is to wind SCREENED Cat5 on a frame (or picture frame). On some sets leaving the screen floating on MW and earthing one end on LW works best. Each pair is treated as one wire. So 5 turns of Cat 5 is 5, 10 or 20 turns by parallel or series of the cores. Some sets need extra series inductance switched in on LW and some don't with all 4 pairs in series. Some need two sets of pairs in series - parallel for MW and all in series for LW. Some sets need the loop to be tuned. The AM/FM semiconductor tuners work best with about 4 turns on a large frame. No design of loop (size/inductance, tuned/untuned) will work even for all valve sets that need an external aerial. They seem to have optimised for an open wire, not a loop, and some sets maybe on 3m, others much longer.
The Model H is Ever Ready two valve TRF, like 1920s, using the B7G valves. It's got various aerial connection options according to the wire length and needs an aerial. I've not found a loop recipe for it yet. It works better than I thought it would.
The loop (and ferrite rod) and batteries is of course superior to any radio on mains and worst is mains radio with end fed wire.
