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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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25th Aug 2018, 12:44 pm | #1 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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WS19 set audio pick up...
Can I connect a speaker / phones to the pins of a 19 set and listen to the audio without going through the control box? I ask because a friends 19 set is with me and I was trying to see whether I could listen to it. It has no control box and I am not sure of the pins for audio. I did find one with a rather unstable 12v Dc on it. Clearly that's not the one, but I was just intrigued...
D |
26th Aug 2018, 7:54 am | #2 |
Pentode
Join Date: May 2013
Location: Deal, Kent, UK.
Posts: 139
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Re: WS19 set audio pick up...
The "A" set audio output is pin 4 of PL2A. You can connect a speaker between it and ground. The output impedance is 100R as it's designed to feed multiple headsets.
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26th Aug 2018, 12:31 pm | #3 |
Pentode
Join Date: Nov 2015
Location: Maidstone, Kent, UK.
Posts: 131
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Re: WS19 set audio pick up...
I agree with M0sOe Bruce, pin 4 is shown on the circuit diagram connected to a tap on T2A secondary.
Orakle42 |
26th Aug 2018, 3:35 pm | #4 |
Heptode
Join Date: Jan 2003
Location: Tewkesbury, Gloucestershire, UK.
Posts: 690
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Re: WS19 set audio pick up...
For maximum output, you need to match the output impedance to that of the speaker. The required voltage ratio is SQRT 100/8 which is approx. 3.5. I have successfully used a small mains transformer for this connecting the speaker to the 6.3V winding and the output of the set between the 250V and 230V terminals.
__________________
Keith Yates - G3XGW VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm |
26th Aug 2018, 9:30 pm | #5 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: WS19 set audio pick up...
Thanks guys
D |
27th Aug 2018, 1:35 pm | #6 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: WS19 set audio pick up...
If you're looking at doing this, you could do a lot worse than get hold of a "100V line" audio transformer: these have a range of tappings on both the primary and the secondary so can be frobbed to provide a whole range of impedance-matches.
Whatever, don't expect the result to be very loud! |
7th Dec 2018, 9:22 am | #7 | |
Octode
Join Date: Oct 2008
Location: Littlehampton, West Sussex, UK.
Posts: 1,465
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Re: WS19 set audio pick up...
Quote:
I probably have what you need but most of my transformers are in several large wooden boxes which I can't get into just yet but is a heater transformer really what you need. A 240/6.3 heater transformer has a 40:1 ratio which is much the same as the average valve radio audio output transformer and would probably replace the 19 set transformer without the need for an additional one. If you want to tack an extra transformer to the headphone output it needs to be a much lower ratio, about 2 or 3:1. A little transformer which I think would get near this and is readily available and cheap is the Eagle LT700. It's a small transformer intended as the push pull output transformer for little transistor receivers and is less than an inch cube in size. The primary which you'd connect to the 19 set headphone output is centre tapped and would give you a couple of ratios to choose from by using half or all of it. The other thing you could do is use a redundant computer speaker with internal amplifier. Best of luck. Jim |
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7th Dec 2018, 9:58 am | #8 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: WS19 set audio pick up...
Jim
Two good ideas. I have an amp here in fact, but we were trying to make it self contained... Thanks again D |