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Old 29th Nov 2010, 11:58 am   #11
terrykc
Rest in Peace
 
Join Date: Nov 2010
Location: North Hykeham, Lincolnshire, UK.
Posts: 515
Default Re: Single valve receiver circuit required

Quote:
Originally Posted by OErjan_S View Post
... one of my favourites is the 1T4 (DF91) shortwave set,
http://makearadio.com/tube/sw1.php
That looks very much like the radio I built over 50 years ago!

Mine was MW/LW using a Repanco DRR2 coil. Anybody got one of those kicking around?

I used a 1N5GT in mine. Why? Because someone gave me a bare chassis punched for Octal valveholders and it was the cheapest 1.5V Octal Pentode I could find advertised in Practical Wireless!

Most designs at the time used two 500pF solid dielectric variable capacitors, one for tuning and one for reaction. I used a twin gang air spaced one for tuning (one section only), rescued from somewhere, which fitted the pre-drilled holes on my chassis.

Many solid dielectric ones didn't have the smoothest rotation characteristics, so the use of a (much cheaper) pot to vary the screen voltage ensured a nice smooth reaction control.

The headphone was a low resistance one - Government surplus from Duke's in Manor Park -with a salvaged output transformer to drive it. (Low resistance headphones were always much cheaper than high resistance types because of lower demand but my solution suited my limited pocket money supply and worked well.)
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