Lissen/Ever Ready 5214

[Amie]

Mike.

The picture of the underside of your sets chassis shows four of those capacitors. C23 used tags 1 and 2 of the p8 holder of V2 as grounding point . I would have thought that the troublesome capacitor would have been tied to the frame of the VC.

What I've actually done this afternoon on the octal holder is to connect pin 1 (metalizing) to pin 7 (filament negative) together, and tied the capacitor C 23 to that point, I've found a flat LCR 22pF capacitor for the final replacement.

I have to give Peter the credit for pushing me in the right direction on this one as he pointed out that sets with the alternative tuning capacitor were fitted with this component.

Hand wiring a radio chassis was obviously a more skilled job than stuffing components into a circuit board, and misplaced components must have been common occurrence if there was a change in design.

This radio will now be treated to its new MW loop frame and I'll get some photos posted when we get our internet connection back, its a PITA doing forums on a phone!

Thanks.
Amie.

[Mike Watterson]

Good.

[Kalee20]

The K is much better than the Lissen version of the 5214 I have. But I think it has it's original 1939 valves.

Also running on battery reduces the mains interference.

The loops are a better size, more signal and Q, than the flat coils in the lids of attache models, they outperform a decent ferrite rod...

Now that last bit is interesting!

First, my impression is that the Vidor CN420a (flat coil in attaché case lid) is more sensitive than the Model K (frame aerial), at least for receiving more stations. Though, the K sounds better.

Second, the K has a single coil for its frame, with a (non-receiving) series inductor to bring up total inductance to what's needed for LW. Whereas, the CN420a has extra (receiving) coils in its lid for LW, and the 5214 has a dedicated LW frame aerial, so one would expect a greater signal to the first valve, and better performance overall, on LW for the CH420a and the 5214 if all else is equal.

Last, I have been carrying out experiments with replacing the frame aerial in my K with a 160mm ferrite rod, and my findings are that the rod is better! See here.

[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.

[Kalee20]

I'm thinking, there's a man who knows his portable radios 

Thanks Mike for passing on some of your knowledge. Much appreciated.

I'm not sure why you'd replace the frame aerial in a K with a ferrite Rod.

Not obvious, and I hadn't said - but the K is running from a 6V SLA battery, driving a switching power converter providing LT and HT. It has copious filtering, and it's heavily screened (sits in a cavity machined in a solid block of aluminium, walls 10mm thick), but in the K the frame aerial is wrapped round everything. And there are slight whistles audible with weak stations.

Hence, rather than have the RFI generator sitting right in the middle of the frame aerial, I wanted to try ferrite rod aerials where this wouldn't be the case. I wasn't expecting quite such an improvement in performance as I'm seeing.

Incidentally, the CN420a is powered by the same converter, but as the aerial is in the lid it's hinged up out of the way, and it runs as quiet as batteries (despite, in the CN420a, being housed in a, off-the-shelf diecast box).

(And, the irony of using a lead-acid battery to run a radio using valves expressly designed for all-dry operation is not lost on me)

[Murphyv310]

Hi.
Kalee, I'm interested in the switching PSU you use. Is it home built or a commercially made item?

[Kalee20]

It's home built. Actually has three outputs, LT, HT, and GB (so I don't waste any of those hard-earned HT volts in a back-bias resistor). LT is precision regulated; HT and GB are ratioed to LT so themselves are highly stable.

However, it's rather heavy in its use of transformers and inductors, as you can see!

   

I don't want to sidetrack the thread from Amie's 5214, but I'm happy to start another thread if interested 

[Mike Watterson]

Likely that amount of metal degrades a frame aerial, so hardly a fair test. The Zinc of the B cells and F cells in an AD3 would have been differently distributed.

I've designed and built some SMPSUs ( a Cuk based one was best) with a reed and custom coil in series with the LT to turn it on, so only LT batteries needed. Easier to do for 250mA than 125mA, wrong wire and number of turns and the voltage drop on LT can be too much or it may not turn on reliably.
I decided in the end there was no point to mains adaptors on battery only valve sets. Decent alkaline batteries can have a 5 to 10 year shelf life. So I concentrated on recreation of battery packs with as close to original performance in run time and in original size pack, style of label and type of connector.

There isn't a single one of my valve battery sets I'd consider for everyday listening, though some of the Pye and Philips are very very good, they have their own built in AC. The Hallicrafter's S72 is the only one with BFO and "RF Gain" (it's IF gain really) and though it has a regular speaker it takes 2K + 2K headphones, it has uses a massive battery or 115V mains. The only other one with a phone socket is the McMichael 1929 suitcase model. I've plenty battery valve sets with their own built in mains. Some are more sensible to use on battery and most of the Attache style ones are best used on my shaver transformer in a box with an extra hole drilled for the "earth" pin. Any deemed unsuitable to use on mains either have a USA two blade plug or UK 5A round 3 pin plug, they are sold new here for home lighting.


I have some that take lead Acid and I have one large glass lead acid (NOS never filled from 1970 for a plant room battery backup, so worked when acid added). I've also two simulated Lead Acid packs using parallel and series C cells. The combining diodes add enough voltage drop. The 2V is really almost 2.3V fresh charged (drops quickly to 2.1) about 1.7V when flat, best recharged at about 1.85V. The NiMH are a bit more than the NiCd, but have the same 1V recommended end point. The sets with Lead acid were ALWAYS supposed to have the cell(s) swapped, never charged in place. So the NiMH with even Schottky diodes to combine parallel series can be OK. The original gas vent/ acid inlet becomes a fuse. Separate diodes and resistors split and limit the charging voltage, which should never be in situ.

The continental 1.4V LT models with mains used an NiCd of DEAC brand from the 1940s to regulate the mains. US and UK mostly used serial (impossible with German Y8 metal can family), 7.5V to 12V nominal battery. Some later UK models with mains and 1.4V use a selenium rectifier as a shunt regulator and the LT rises alarmingly if one valve fails or is missing. Some of the 3rd party 1.4V & 9V eliminators would rise to 120V and flash over valves if LT wasn't connected and were either for 250mA or 125mA. Models that did both had a screw to connect a 125mA shunt resistor. They are dreadful, again if one valve is dead/out the LT rises too much.
Basically, on series or parallel sets operated on mains the simplest thing is to check volts on the DAF91 or DAF96 as it will be the end of the chain. Should be 1.35V +/- 5%. Most decent series sets have taps or a rheostat to set the LT current, usually stated. The 7.5V nominal battery sets typically at 6.8V. Any purely with either HT or LT via a dropper off the mains want to be run off a shaver transformer. 1930s to 1960s concepts of safety and 70 year old insulators between metal panels and live chassis are not good.

[Ed_Dinning]

Hi Folks, on the battery eliminator topic, I've just repaired an Ever Ready Sky Baronet from the 50's. It used a re-stuffed B141 battey pack, not of my design, but the LT cell's chemistry gave 1.55V on load.
Valves tested as extremely low emission on an HSVT, but worked OK in the set. They may well have short lives.

Ed

[Mike Watterson]

A fresh Zinc is 1.6V and a fresh Alkaline is 1.54. But they will drop quickly in minutes of use. The 1.35 V to 1.4V is close to the average of the flattest part of the discharge curve.
It's why you shouldn't fit fresh batteries every time you demo.
End point is taken as 0.9V per cell (fall off a cliff point), but for LT filaments it's about 1V to 1.1V, the Mixer/Osc will stop first.
My B141 pack uses 60 x Alkaline AAA for HT and several Alkaline cells in parallel for LT, I forget which size. So as to use up HT and LT at about the same time. The original used layer cells for HT, but higher capacity than PP3 per cell. The Alkaline AAA is close to original. It's all made of folded card and cut up coffee tin for the terminals. It's actually the BEREC badged version I have. I have the Sky Casket also, which I think takes same pack. I've not got a Sky Princess which is an earlier version of the Sky Baronet.