I put a DBM together last night and did some testing. The core is as the previous test indicated. 10 turns = 100 uh. My test indicated a 10 to one VFO to signal ratio to produce the best results. example 500 mv LO and 50 mv RF produces 10 mv IF. I plan to do another with more inductance and see how it effects the operation. I'm posting the construction.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHBNXHbOxGHasBveF9nLGUFnLQl2IUCbCrY7GgmAPGkafhDW91f9qXUgWnqnnOQnra6qtv2QA6WYEAt48btFSXK6S7V7pZk-gy099Kb_sSgOk4wDodBEvLVGM6NU-y4pOk7PcIBKNtvXmo/s640/IMG_20181111_234013.jpg) |
I cut 3 wires to the same length and wrap them together. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjV4J8-_2vNklx4LGsXkR3LtO48gauwcGmsz4XqM7p6oQOzXhRmG8wPJre2DYJHR_HS3LoXDBDJQpAZIfYZcHW7Ml_O5lHM_qboFKFdpB0sFcGpXT2ys9LVYwkQJ9KrpT26qmKe-l2XbylY/s640/IMG_20181111_234542.jpg) |
The wrapped cores with 3 coils . |
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![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYEUKNuWxmmm89nF3s0b14z5myJhybz_2FnVmM0aAbQ0zRdvuddWDCZ6C_uEQnYnAlhkZ1bl3gY9ka7PuVPsoFZ2xBk_YCsjFtNzhoP41cJO89zvCfTPI6ZAJyUXjivws9JZDNLfKqhYRV/s640/IMG_20181111_234741.jpg) |
Separate the wires and prepare to clean the varnish from them. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKk2SRVe0W7Z2FywzL-2CBoAmWJMDqE-lEeH-iibVfM4earo5qPVLMIZIEjq5ygq8cdIqopQPd3dsBcueczYbYO3Z91eYjr5n2KgaRke_OFxCnPw2zsL29eqvD3bsQuZelukK8nLr8_N3l/s640/IMG_20181111_235541.jpg) |
The wire can be soldered without stripping the varnish. The varnish will burn off IF you get the wire hot. I put a drop of solder on the bare end and work down it. You can also use a small flame to burn the varnish off. An alcohol lamp is ideal for this but a torch work too. After heating removing the soot and ash with an alcohol wipe works well. I heard of a guy using a small cup of alcohol to dip the wire in. After setting it on fire he turned it over then things went bad. The wipes are safer. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiW9bfScapC_BvPCTmWElhYK0G7OHRCliPcKZ-ayFWB-05eJWG6sVVdSkmh6g6tbyoF8TL5rKoNjvLEQVIRW-1nLX7_SJ60jswuZ47KybDWAHiMOqN5dAAeIVqy6IDBof1ZHN4lIoeKAdnu/s640/IMG_20181112_000214.jpg) |
Use the ohmmeter to find a coil, this will be the primary twist it to ID it. Find another coil. Connect one end of it to the other end of the remaining coil. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSc3oPuxYkvYuF-ltwzg84-GcXtChOIAKPINe7YHxA1ZNHOamz494egVjrYtpoxWnf_8ciw2znQ8yrtutd-BIaCrvsUbHUKw3jgkXr7av6zByXv7XXSThxA9Ook02431b9FIRtr_ReYQ6i/s640/IMG_20181112_001944.jpg) |
Make a pin board with the layout for a diode diamond and the I/O. A piece of perf board might be better if you have some.Run a ground lead from LO and RF inputs. Connect the primaries and center taps of the secondary. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSAbKJ5d4b_fgCrCmpXs6oBWt6nPcYkfQurq9l4ZYI5FvunqrTdT-_rMjQ_WP2oUdNGWMyB9aXLLxfCEAx49iNLpdoUg4unib8slEGs3EneQNooeRqoE9Lzzq6Tm_g9pQVCZAiAHlguA0y/s640/IMG_20181112_003007.jpg) |
The remaining wires go to opposite sides of the diamond. Now all that's left is mounting the diodes. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjH6HsoSXOvIz57LUcU4oxLp8wZ0IkTpkX7Y5fiYePj-NLs5jgCwxjOqd4x-FQVuQdIs9gYIWXkNlTgbIiA9_L_-URXpGou9Wd0Ts4eOTJh6769YOVIcbzjTYzKJYjiEZK2QUD76klj8_KF/s640/IMG_20181112_003325.jpg) |
I use clip leads as heat sinks. Pair the head and tail of a pair of diodes and connect them to a pin. Pair the other diodes head to tail and connect them to the opposite corner. |
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![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUzZw1iMMJ93nbxls4J0mlkHvo7dlacTDlK8QLyy3c4LPuYIsBGkl6V2iICdpwaVAAa1RVOk95xNAcakiRL-FwNty4vvsKCcc1KEV3gBIJVNBdLNyKzUG_oq-JgZDjow3aSd78hmH36TFR/s640/IMG_20181112_003546.jpg) |
Take a head and tail and attach them to a corner. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS7G7cuZgVGOcHyTEl5stygENwNWsuM4m588KtKSLmsWYPTFUFjWumfCavlQ7lh2cpubNrmfakokdYQQ5ddh8RIQENBvCpqVyynNfxVFZlHVWXkfcIk50UbyDbSP1naxtzNy9z95m7jruV/s640/IMG_20181112_003732.jpg) |
connect the remaining ends to the last pin. |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilvo5X679bjS266nC2maykddmcT5edeQq3tB94moq6E2MZK9WZCjrrKhlujLl782hzFyfq3xYCyFPIkXnSj_AGjN8F7GkoNBZ6vxc0UB_u53wsxPiqI2huNi4lMsR68yB3pobBOYkyCCBJ/s640/IMG_20181112_003848.jpg) |
The finished product. This works well for a test bed to try the cores. The final product will probably be put in a metal box. You can attach the cores to a ground plane by soldering the ground connections to it. Then use the 4 leads that connect to the diodes as stand offs to solder the diodes to. |
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I'm feeding it a 4001KHz @ 500mv and 4000KHz @ 54mv signal and getting a 1KHz @ 5mv output. (best I can remember. I should have wrote it down. I took pictures of the setup but can't read them.) Anyway it works it is not sensitive enough. I will try more turns on the coils.
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