hi guys and dolls, ive been given a hallicrafters model tw-500 today from my good friend joe guilfoyle.i powered it up on 110 v , all i got was crackling at speaker when the brimar 3v4 valve was waggled ,noticed the heaters in the valves were not working, the telescopic aerial is missing, as are the two double knobs .90v battery connector missing ,just three wires hanging red green and black, wondering does a 1.5 battery need to be fitted somewhere to heat the elements? needless to say i dont have a schematic to hand, btw should there be a ferris aerial in this model?any advise gratefully received or parts offers, welcome , some pics on the way, best regards maitiu.
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hallicrafters tw-500
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01-12-2013, 07:24 PM
The service manual is available to download for free here:
http://www.boxspringsonline.com/hallicra...structions Colin
01-12-2013, 07:58 PM
No Maitiu - you don't need a battery - the set is designed to work off 105-120V DC or AC 50/60 Hz, or from 90V & 9V batteries, so you're fine in that regard with 110V.
You'll see from the circuit that when used on batteries, it uses a 90V HT battery, and a 9V battery for the heaters. Hence as the heaters ('filaments') are all 1.4V, and the LT battery is 9V, they must be in series, (like Christmas tree lights, and trade union strikers - one out - all out!), which means that if any one or more are open circuit, none of the valves will light up - not that you'll see much glow from them except in a darkened room. As a first step, I'd suggest that you pull out the valves and check the heaters for open circuits. (They're all pin 1 & 7). You will incidentally need an antenna - just a few feet of wire will do temporarily, to get any signals. Hope that helps a bit. Best of luck with it - it looks an interesting set!
Regards, David.
BVWS Member. G-QRP Club Member 1339. 'I'm in my own little world, but I'm happy, and they know me here' 
01-12-2013, 08:49 PM
Hallicrafters have to be one of the most prolific set makers of the valve era, did some damn fine SW receivers.
Lawrence.
01-12-2013, 10:06 PM
thanks for that david, very useful info indeed, this poor thing has been through the mill , the speaker was jammed in at an angle , were someone tried to do a job of sorts removed the ferris and then realised it was beyond them, if they had of taken the chasis out of the case they might have suceeded, as you see colin has sent me a schematic which ive downloaded and i am very grateful for ,ive not got alot of experience of these battery/mains sets of this era, but ill get there now , especially with the christmas lights knowldge, best regards maitiu.
02-12-2013, 06:37 PM
thanks david, ive discovered two valves are o.c filiment wise, 1l6, and 1u4, so a hunting i shall go, prob to the uk as this stuff is as scarse as hens teeth over here , great to get the bit of advise , best regards maitiu.
03-12-2013, 03:48 PM
Make sure all the heater shunt resistors are ok, they can affect the performance of the valves if duff, they balance out the valves anode/screen current due to the valves being directly heated and the heaters being connected in series, the output valves heater is wired for 2.8v heaters as opposed to 1.4v.
Good luck. Battery valve schematics always confuse me, especially American ones, I don't know about you guys. Lawrence
03-12-2013, 04:04 PM
(03-12-2013, 03:48 PM)pwdrive Wrote: Make sure all the heater shunt resistors are ok, they can affect the performance of the valves if duff, they balance out the valves anode/screen current due to the valves being directly heated and the heaters being connected in series, the output valves heater is wired for 2.8v heaters as opposed to 1.4v.thanks for that lawrence, as far as confusion is concerned , the schematic that was sent too me has different valves fitted , they must be american or substitutes, mine are mixed , some mullard and some briamar regards maitiu.
03-12-2013, 04:22 PM
Maitiu, I don't know the equivalents, but your Hallicrafters is all 1.4v @ 50ma heaters according to the schematic, except the 3V4 which has a center tapped heater and in the schematic is wired up for 2.4v (@ 50 ma)
It's years since I delved into valve battery portables, someone on the forum might be able to advise on equivalents etc. Lawrence. |
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