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Skywave · 10th Dec 2017, 9:50 pm

G6T: thanks.

The only reason I included the d.c. resistance measurements is in the hope that someone might be able to use those in order to assist the production a cct. diag.
Unfortunately, your suggested link did not provide any info.

As for my signal tests, the only reason I used an audio / L.F. signal on one port was because of this device's name: 'modulator' - and, in retrospect, that tripped me up. To me, 'modulation' should refer to modulation such as A.M., F.M., P.W.M., P.C.M. etc. So on that basis, I feel that a 'D.B.M.' - which is what this is - should be known as a 'mixer' - a 'double-balanced mixer'. Anyway, that as maybe: a further discussion about that is not relevant to this thread.

This device - a D.B.M. - has four toroids: any idea why four? Usually two are sufficient.
The fact that this device has 3 BNC sockets, to me, says that this is an 'all R.F. device' - with a typical usage as you have suggested.
So, developing that line of thought, of the 3 ports, A, B and C, which one becomes the O/P port?

Al.

10th Dec 2017, 9:50 pm	#3
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Hatfield modulator: info.? G6T: thanks. The only reason I included the d.c. resistance measurements is in the hope that someone might be able to use those in order to assist the production a cct. diag. Unfortunately, your suggested link did not provide any info. As for my signal tests, the only reason I used an audio / L.F. signal on one port was because of this device's name: 'modulator' - and, in retrospect, that tripped me up. To me, 'modulation' should refer to modulation such as A.M., F.M., P.W.M., P.C.M. etc. So on that basis, I feel that a 'D.B.M.' - which is what this is - should be known as a 'mixer' - a 'double-balanced mixer'. Anyway, that as maybe: a further discussion about that is not relevant to this thread. This device - a D.B.M. - has four toroids: any idea why four? Usually two are sufficient. The fact that this device has 3 BNC sockets, to me, says that this is an 'all R.F. device' - with a typical usage as you have suggested. So, developing that line of thought, of the 3 ports, A, B and C, which one becomes the O/P port? Al.