30-10-2012, 06:57 PM
Thanks for spotting the typo Lawrence - yes, it's the DRR2 coil as I showed in the datasheet in my first post - not DDR2.
That looks a dinky little one-valve TRF radio Alan. Looking at the circuit, I guess the valve was a 1T4 or something similar, which in 1959 was 6 shillings - less than the cost of one red spot surplus transistor, and I'm sure it would have performed much better than this 'Focus' transistor jobby. Three fixed caps, two variable caps, two resistors, plus the coil and valve. What's not to like about that? Maybe I should build it to test my coil!
If you can lay your hands in the DRR2 coil Alan, it would be a great help if you could measure the inductance of the various windings for me. (I just know that you'll have half a dozen or more inductance bridges!). In particular whether I'm right in my assumption that the tap on the MW coil is about 10% from the bottom, and what the inductance of the coupling coil is.
This is a typical diversion to which I'm all too susceptible - I've got a heap of half-finished projects, we'll be away for much of November and my wife's sound advice is ringing in my ears: 'Don't you think you've got enough on your plate - wouldn't it make more sense to finish one thing before you start yet another?' Well of course it would, but where did sense ever come into the equation - what's that all about?
That looks a dinky little one-valve TRF radio Alan. Looking at the circuit, I guess the valve was a 1T4 or something similar, which in 1959 was 6 shillings - less than the cost of one red spot surplus transistor, and I'm sure it would have performed much better than this 'Focus' transistor jobby. Three fixed caps, two variable caps, two resistors, plus the coil and valve. What's not to like about that? Maybe I should build it to test my coil!
If you can lay your hands in the DRR2 coil Alan, it would be a great help if you could measure the inductance of the various windings for me. (I just know that you'll have half a dozen or more inductance bridges!). In particular whether I'm right in my assumption that the tap on the MW coil is about 10% from the bottom, and what the inductance of the coupling coil is.
This is a typical diversion to which I'm all too susceptible - I've got a heap of half-finished projects, we'll be away for much of November and my wife's sound advice is ringing in my ears: 'Don't you think you've got enough on your plate - wouldn't it make more sense to finish one thing before you start yet another?' Well of course it would, but where did sense ever come into the equation - what's that all about?
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
