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zenith: from network mode to battery mode

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Forum » Apparate: Physik - Radios - bis TV » MODELLE IM RADIOMUSEUM » zenith: from network mode to battery mode
           
Sandor Selyem-Tóth
 
 
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29.May.21 11:02

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Gentlemen, how do I switch the radio from network mode to battery mode?

Br,

 

STS

Michael Watterson
 
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30.May.21 13:57

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Usually the mains-battery switch is on a dock socket for the mains plug.
Some Hallicrafters and Grundig sets also are like this.
Some models have a spring loaded drum for the mains cable and it only reconnects the batteries when the cable is fully retracted.

Sandor Selyem-Tóth
 
 
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30.May.21 18:08
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Dear Michael! Yes, Thanks!

Sandor Selyem-Tóth
 
 
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30.May.21 18:19
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Yes you have the docking space! Thanks to Michael, too.
I'll show you in the photo.
The other comment based on my rehearsals, I followed the sketch of a colleague Heigl, unfortunately contains the error. The 100 Ohm resistor on the battery connector started to burn, I turned off the power in time. An interesting result of this problem was that the original volume of the hitherto quiet radio had returned.
I show the corrected drawing as well as the connector I made (Plastic bottle cap and 4 RCA connectors).
I hope I can help the new G500 owners.

It is interesting that instead of 90 V, 75 V is enough, and then I convert it to 90 V with such an extra block. There are 3 in it now.

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Dieser Beitrag wurde am 09.Jun.21 18:30 von Sandor Selyem-Tóth editiert.

Michael Watterson
 
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30.May.21 19:04
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Only the very fresh batteries are 90V (actually a little more) and 9V. 70V to 85V is fine for HT and 7.5V to 8.2V for LT. The original "end point" would have been about 55V to 60V for HT and about 6V for LT depending on the tube condition. The gain and max volume tails off gradually with HT dropping, but the Local Oscillator tube (valve) stops quite suddenly between 1.15V and 0.9V depending on the tube condition and the band. The higher  frequencies fail first as tube or battery ages.

I made a replica pack with 6 x Alkaline D cells, 60 x Alkaline AA cells and important are fuses! Especially on the HT as the AA alkaline cells are rather lower resistance than the layer cells or even the older Zinc B cells used in non-layer HT supplies.

Michael Watterson
 
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30.May.21 19:12
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Also I use a European Shaver outlet transformer mounted on a surface box. These have about 4kV isolation, current limiting core at about 20W and sometimes a thermistor.

I add 2 x 1nF 2KV XY rated capacitors from the outputs to Earth otherwise there can be a buzz.

They work well for live chassis European/UK mains/battery radios and most USA sets, as they have 110V and 220V. I drill a 3rd hole at the 220V outlet and modify it so the USA plug doesn't fit. Most of the UK battery/mains models thus have the old UK 5 Amp three round pin plugs.

The Hallicrafters S72 has too many tubes so it doesn't work so well on the adaptor. It orginally had an option 220V -> 110V transformer.

Sandor Selyem-Tóth
 
 
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30.May.21 20:07
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Yes, the Braun razor adapter is a good solution for more modern transistor Zeniths, I use it too.
110-240 V / 12 V / 400 mA. Very good solution.

Michael Watterson
 
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30.May.21 20:21
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The kind I mean is usually mounted flush in the wall near the mirror and sink in the bathroom. It's just isolated 110 & 220V from the 220V wiring so people don't get electrocuted. No low voltage and two mains outlets. It's actually a centre tapped output 220V to 200V transformer.

I need to get a 50W version, but almost all the 220V to 100V solutions are either 1000W to 2000W for building sites or autotransformers that are actually dangerous for modern USA appliances as the live of the European mains can easily be on the USA socket. I'd only run old USA gear of an isolated 220V to 110V transformer, but the shaver outlets are limited to 15W to 20W, by design.

Sandor Selyem-Tóth
 
 
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10.Jun.21 04:41
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ebay.com/itm/201745684390?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Michael!

Lehet ez jó? 3-4 db Li-on akkumulátorral? 

 

BR,

 

STS

 

 

Michael Watterson
 
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10.Jun.21 10:06
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Most SMPSUs have too much RF noise. I built some Cûk architecture switchers with extra input and output filters for 1.5V and 7.5V nominal inputs. I used a home made coil on a reed switch with the LT current on it to turn it on/off.

Li-on are particularly tricky to use. The newer NiMH are safer and easier and not much larger per AH per volt. The advantage of Li-Ion is low weight and for the pouch type, the slimless. NiMH may be left discharged. Li-Ion may not, also the capacity per full discharge drops faster.

All the battery valve-tube sets are so infrequently used that I decided replicating the battery packs with alkaline cells is best. Also unlike li-Ion or NiMH, the quality ones have very low self discharge, they may still run even after five years storage. They were designed for battery use. Actually some models have dubious quality of built in mains adaptors. I always check that the filaments are 1.25V to 1.4V on mains power. Philips recommended 1.35 V +/- 10%, but aiming for 1.3V is better.

 It's important to store the sets without batteries and store the replica packs empty.

Sandor Selyem-Tóth
 
 
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02.Jul.21 12:11
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Now I solved the anode with 22 Li-Ions and 2 with the heating (3500 mAh per piece).
wondering what the capacity of the contemporary sites could be in mAh.

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