Dynatron Nomad

[opus242]

Hi all
Does any have or know of a good loudspeaker replacement for a dynatron nomad Tp11
Many thanks

[crackle]

Loudspeakers were very often not specific to a single radio. Why not give the spec. of the loudspeaker you want, to save everyone having to look it up before they can potentially help you, Overall dimensions, fixing centres, impedance, depth front to back may also be important.

Mike

[opus242]

Morning
Yes .. good point.
Have included a picture . The unit is 7 inches by 4 1/8 .
The circuit diagram states 50 ohms.
Many Thanks

[crackle]

That one is pretty unusual, what exactly is wrong with it, is it open circuit, have you checked the solder connections the the flexible braid that goes to the speech coil.

Mike

[opus242]

The coil is rusted up and there is no movement in it.
It's showing as open too.
Its got left in a very damp garage for a few years most of the unit was damp inside but have been able to get it working .
Just the speaker to go.

[Malcolm G6ANZ]

I got one for my Dynatron from here:
https://www.ebay.co.uk/itm/Replaceme...m1c7a10bd34:m:
The speaker on mine was open circuit.
I know eBay is sometimes frowned upon here but this just a link to a part nor a sale

Malcolm

[Herald1360]

Finding a 50R 7*4 loudspeaker may be difficult.....

Maybe fit some beefier output transistors- AC128 or similar and use a 15R one? You might need to tweak the bias. Silicon PNP TO220 would be bombproof but would certainly need to be rebiassed.

Alternatively, you could simply (reversibly?) fit a cheap audio amp module to do the same job again with 8 or 15 ohm speaker. A secondhand Hacker one would be nicely insulting to the set

Edit: just seen the Ebay link but it seems to refer to 8R speakers rather than high impedance ones.

[opus242]

Thanks for the feedback.

Just a thought.. would having a 15 or 8 driver with suitable resistor in either parallel or series work?
The driver would need to quite sensitive I would imagine.

[Herald1360]

Yes...... but even a15R driver, padded up to 50R would get less than 10% of the audio power.

A 2:1 stepdown audio transformer would turn 15R into 60R- not a bad match. You would need to be careful with dc though- a 1000uF cap between the output of the amp and the TX primary would be a wise precaution.

I'd go with siliconising it myself_ BTDT with a Hacker which was much trickier to rebias being a directly coupled amplifier. You can keep the old bits safe in case the real deal speaker does turn up.

[opus242]

Hi all
This may be a project too far for me. I have not worked with transistors before and it end well.
Cheers

[simpsons]

I have one of these radios which is of no interest to me. I will check out the loudspeaker and if it is what you need, it's yours for p&p.

'Will get back to this thread with further details soon.

Chris

[Techman]

'Will get back to this thread with further details soon.

From the 'edit' at the bottom of the previous post I would be guessing that the OP has put the set up for sale somewhere as he no longer wants to bother with it, so I wouldn't go to a lot of trouble just for the moment unless you hear otherwise.

[opus242]

Simpson's . Pm sent. Many Thanks

[Herald1360]

Looks like an incontinent rocking horse has pitched up! Hopefully it can be sorted fairly easily now.

[simpsons]

Hi Rob

Please find attached photos of the loudspeaker as promised. Is Techman a Friend?

The speaker is funtioning well and as it has been removed from a Nomad, I am confident that it is what you need but just in case have a look and confirm.

Best wishes

Chris

[opus242]

Morning
looks perfect.
many thanks

[opus242]

Many thanks to Simpsons radio is up and running.
Many thanks