Dewtron Wave Trap. - UK Vintage Radio Repair and Restoration Discussion Forum

G6Tanuki · 24th Feb 2018, 12:12 pm

Thinking about another recent thread on using loop antennas to improve reception of Caroline etc brought back memories of a 'thing' often advertised in the likes of Practical Wireless called the "Dewtron Wave Trap" which supposedly boosted signal strength on portable transistor radios.

It was in two parts - a plastic box with a tuning-knob, and a strange flattened-cylindrical plastic-covered device - the two being connected by a cable. I believe the plastic-box bit had a battery in it.

Did these things work? And if so what was the circuit? I'm guessing that it was probably a single-transistor amplifier, with ferrite rod antennas in the two parts, the cable between them providing physical separation so avoiding magnetically-coupled feedback.

Anybody still got one in captivity? Or a circuit?

stevedee · 24th Feb 2018, 1:26 pm

I don't know, but I wonder if this helps: http://makearadio.com/misc-stuff/contra-wavetrap.php

Also look at the "contra coils" link on the same page. Could that be the strange flattened cylinder you mentioned?

G6Tanuki · 24th Feb 2018, 4:32 pm

That's not really anything like the Dewtron version: there's pictures of one here:

https://www.worthpoint.com/worthoped...gnal-426873165

and from the shot of it with the cover off it definitely has a transistor in there and a PP3 battery-connector.

I found a description from a mid-1960s Practical Wireless article.

"Dewtron" it seems were also involved in making guitar effects-pedals and an early analog synthesizer. Some company history here: https://en.wikipedia.org/wiki/Dewtron

stevedee · 24th Feb 2018, 5:33 pm

Quote:

Originally Posted by G6Tanuki

That's not really anything like the Dewtron version...

Yes you are right, from the description (and photos) the Dewtron appears to be just an rf amplifier. It looks like you have to tune it to suit the MW frequency of interest.

The white round thing is a window sucker cup, presumably for use in the car.

Herald1360 · 24th Feb 2018, 7:07 pm

Sounds like the oil from that particular snake might actually have lubricated the radio to some purpose!

Calling it a wave trap is a bit of a misnomer, though, that name is usually reserved for a circuit to block an interfering signal such as the Athlone blocker in the R1155.

24th Feb 2018, 12:12 pm	#1
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Dewtron Wave Trap. Thinking about another recent thread on using loop antennas to improve reception of Caroline etc brought back memories of a 'thing' often advertised in the likes of Practical Wireless called the "Dewtron Wave Trap" which supposedly boosted signal strength on portable transistor radios. It was in two parts - a plastic box with a tuning-knob, and a strange flattened-cylindrical plastic-covered device - the two being connected by a cable. I believe the plastic-box bit had a battery in it. Did these things work? And if so what was the circuit? I'm guessing that it was probably a single-transistor amplifier, with ferrite rod antennas in the two parts, the cable between them providing physical separation so avoiding magnetically-coupled feedback. Anybody still got one in captivity? Or a circuit?

24th Feb 2018, 1:26 pm	#2
stevedee Retired Dormant Member Join Date: Feb 2018 Location: Horsham, West Sussex, UK. Posts: 19	Re: Dewtron Wave Trap. I don't know, but I wonder if this helps: http://makearadio.com/misc-stuff/contra-wavetrap.php Also look at the "contra coils" link on the same page. Could that be the strange flattened cylinder you mentioned?

24th Feb 2018, 4:32 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Dewtron Wave Trap. That's not really anything like the Dewtron version: there's pictures of one here: https://www.worthpoint.com/worthoped...gnal-426873165 and from the shot of it with the cover off it definitely has a transistor in there and a PP3 battery-connector. I found a description from a mid-1960s Practical Wireless article. "Dewtron" it seems were also involved in making guitar effects-pedals and an early analog synthesizer. Some company history here: https://en.wikipedia.org/wiki/Dewtron Attached Thumbnails

24th Feb 2018, 7:07 pm	#5
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Dewtron Wave Trap. Sounds like the oil from that particular snake might actually have lubricated the radio to some purpose! Calling it a wave trap is a bit of a misnomer, though, that name is usually reserved for a circuit to block an interfering signal such as the Athlone blocker in the R1155. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O