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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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18th Sep 2021, 5:17 pm | #1 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Valve MF pantry transmitter.
I got bored... And built a MF pantry transmitter using an ECL80.
The triode is an xtal oscillator which feeds the output stage which is screen modulated using a backwards connected transistor radio 'LT44' driver transformer to connect to the high impedance headphones output of the ancient Nokia phone I use for streaming. Feeding audio to my Roberts R707 it sounds rather good. Currently listening to a bunch of Dusty Springfield tracks through ithough.... The R707 has some serious punch and really handles Dusty's wide open vocal style well. Play loud and forget about the neighbours!! |
18th Sep 2021, 5:47 pm | #2 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,300
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Re: Valve MF pantry transmitter.
Sounds good, any chance of posting the schematic?
Peter |
18th Sep 2021, 7:28 pm | #3 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Valve MF pantry transmitter.
Sure - Ii'll post a schematic and suggested component-values [hand-drawn, I no longer have an Autocad license] in a couple of days.
It really does seem to work well, it's great to be hearing Dusty's wonderfullyfully full-on vocals resonating round the summerhouse. [Historic sidenote: I'm using a 1.333MHz carrier crystal that first did duty as the clock-oscillator in a 1970s |D|I|G|I|T|A|L| PDP8E.] |
18th Sep 2021, 7:49 pm | #4 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,970
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Re: Valve MF pantry transmitter.
The usual caution applies: you should watch the range, depending on your domestic circumstances. Even a weedy ECL80 can chuck out quite a bit of power with a half decent aerial.
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18th Sep 2021, 7:59 pm | #5 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,300
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Re: Valve MF pantry transmitter.
Thanks Paul, noted. I certainly do not want to go outside the boundary of the house.
Peter |
18th Sep 2021, 8:16 pm | #6 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Valve MF pantry transmitter.
For reference, the 'output' part if my ECL80 panty-transmiter consumes 10mA at 220V.
It's not in in any way coupled to any of my 1.8/3.5/5.5MHz "cloudwarmer "NVIS ham-radio antennas. Though part of me wonders just if there's anys sort of "DXCC" certrificate for MW pantry-transmitters or their Band-II FM equivalents. |
18th Sep 2021, 8:54 pm | #7 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,400
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Re: Valve MF pantry transmitter.
Reception report from OFCOM?
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