View Single Post
Old 10th Dec 2017, 7:23 pm   #1
Skywave
Rest in Peace
 
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
Question Hatfield modulator: info.?

As per photos. Can anyone here tell me more about it and typical uses, please?
It's called a 'modulator' and it does indeed look like some form of a 4-diode balanced modulator. I made some measurements and did some tests:

D.C. resistances:
Port A to gnd.: v.low.
Port B to gnd.: v. high.
Port C to gnd.: v.low.
Port A - port C: low.
Port A - port B: high.
Port B- port C: high.

Signal tests.
Port A: Input: 10 MHz C.W. @ 100 mV rms
Port B: Input: 10 kHz C.W. @ 100 mV rms
Port C: Output: 100% A.M. modulated waveform, distorted. Envelope freq. of 20 kHz.

The signal tests were simply inspired guesses as to what to feed in where and how much. The 'guesses' were simply because I don't know enough about this item to make what probably should have been sensible connections, etc. Which takes us back to where I came in: I would like to discover more about this item. A cct. diag. would be useful.

Any knowledgeable members here?

Al.
Attached Thumbnails
Click image for larger version

Name:	HATMOD1.jpg
Views:	136
Size:	40.2 KB
ID:	153752   Click image for larger version

Name:	HATMOD2.jpg
Views:	127
Size:	44.0 KB
ID:	153753  
Skywave is offline