29-01-2018, 11:53 AM
Post #23 has really got me confused, Mike!
No - if B-F is the MW coil, I-E must be the MW coupling coil.
I-E is not bypassed by switch II. Switch II connects LW coupling coil D-A in parallel with the MW coupling coil.
As for the DC resistance, it obviously cannot be as low as 0 ohms but nearly three times the value of the LW coupling coil does seem somewhat excessive!
This doesn't make sense either because, from my comment above, Sw. II would have to be closed on LW and open for MW.
Also, try as I might, I can find no trace of Switch V. Should I get my eyes tested? Please tell me where it is! (I have no problem with the other switches in the I to VII range, but not switch V!)
If the LW coil is o/c as your measurements suggest, I can't see how a 198kHz signal would pass through the IF strip which must, of course. be working otherwise the set wouldn't work on MW.
198kHz + 120kHz = 318kHz = 943 metres. Does the radio you are using really tune above 300kHz/below 1,000 metres on LW?
Obviously, if you tune the set to the 2,000 metre end of the band, the LO, if working, will definitely fall withing the LW frequency range.
Quote:the aerial coil between tags I & E it is listed as 0 ohms but the reading is 8.4 ohms.
Question. Would you expect to see a resistance of 0 ohms on that part of the coil, is it not the LW section of the primary
as it appears to be bypassed when switched for MW reception
No - if B-F is the MW coil, I-E must be the MW coupling coil.
I-E is not bypassed by switch II. Switch II connects LW coupling coil D-A in parallel with the MW coupling coil.
As for the DC resistance, it obviously cannot be as low as 0 ohms but nearly three times the value of the LW coupling coil does seem somewhat excessive!
Quote:(switches 1 to 6 are all closed for MW, and only 4 & 5 are closed for LW)
This doesn't make sense either because, from my comment above, Sw. II would have to be closed on LW and open for MW.
Also, try as I might, I can find no trace of Switch V. Should I get my eyes tested? Please tell me where it is! (I have no problem with the other switches in the I to VII range, but not switch V!)
If the LW coil is o/c as your measurements suggest, I can't see how a 198kHz signal would pass through the IF strip which must, of course. be working otherwise the set wouldn't work on MW.
198kHz + 120kHz = 318kHz = 943 metres. Does the radio you are using really tune above 300kHz/below 1,000 metres on LW?
Obviously, if you tune the set to the 2,000 metre end of the band, the LO, if working, will definitely fall withing the LW frequency range.
