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-   -   Valve MF pantry transmitter. (https://www.vintage-radio.net/forum/showthread.php?t=183948)

G6Tanuki 18th Sep 2021 5:17 pm

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!!

Electronpusher0 18th Sep 2021 5:47 pm

Re: Valve MF pantry transmitter.
 
Sounds good, any chance of posting the schematic?

Peter

G6Tanuki 18th Sep 2021 7:28 pm

Re: Valve MF pantry transmitter.
 
Quote:

Originally Posted by Electronpusher0 (Post 1407736)
Sounds good, any chance of posting the schematic?

Peter

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.]

paulsherwin 18th Sep 2021 7:49 pm

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.

Electronpusher0 18th Sep 2021 7:59 pm

Re: Valve MF pantry transmitter.
 
Thanks Paul, noted. I certainly do not want to go outside the boundary of the house.
Peter

G6Tanuki 18th Sep 2021 8:16 pm

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.

turretslug 18th Sep 2021 8:54 pm

Re: Valve MF pantry transmitter.
 
Reception report from OFCOM? ;D


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