{"id":2042,"date":"2016-10-29T13:29:00","date_gmt":"2016-10-29T02:29:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2016\/10\/29\/done-jans-amazing-mate-for-the-mighty-midget-receiver\/"},"modified":"2025-07-21T12:38:44","modified_gmt":"2025-07-21T02:38:44","slug":"done-jans-amazing-mate-for-the-mighty-midget-receiver","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2016\/10\/29\/done-jans-amazing-mate-for-the-mighty-midget-receiver\/","title":{"rendered":"DONE! Jan’s AMAZING Mate for the Mighty Midget Receiver"},"content":{"rendered":"

<\/span><\/div>\n
<\/a><\/div>\n
Hi Bill,<\/b><\/span><\/div>\n
<\/b><\/span> <\/b><\/span><\/div>\n
Finally the Mate for the Mighty Midget is finished, just in time for the G-QRP Valve Day 12-13<\/b>th<\/b><\/sup> of November.<\/b><\/span><\/div>\n
Got the LO fixed for 40m by lowering the parallel capacitor from 150 pF to 100 pF.<\/b><\/span><\/div>\n
Also the 68 pF series capacitor was lowered to 33 pF for some more band spread on 40m.<\/b><\/span><\/div>\n
It now receives from about 7.0 to 7.4 MHz and from 3.45 to 4.0 MHz<\/b><\/span><\/div>\n
Had to exchange C1 in the end, the one used initially quit every now and then.<\/b><\/span><\/div>\n
I only had a large 3 section variable in the junk box covering 10-550 pF, which works fine now.
For the lower end of 80m I had to add additional 47 pF next to the 47 pF trimmer caps, so there it is about 600-650 pF max!<\/b><\/span><\/div>\n
At the high end of 40, it is also just not too much.<\/b><\/span><\/div>\n
The meter was used as a position indicator for C1.<\/b><\/span><\/div>\n
Tried several ideas, but with no separate tube for AGC, I couldn\u2019t get it to work as a S- meter<\/b><\/span><\/div>\n
Read something about audio derived AGC, maybe this is worth a try.<\/b><\/span><\/div>\n
<\/b><\/span><\/div>\n
The BFO can be switched off for AM reception.<\/b><\/span><\/div>\n
Simultaneously the input on the mixer side of the crystals is disconnected but still coupled by some capacitance of the switch wires.<\/b><\/span><\/div>\n
AM reception is possible, but not very good.<\/b><\/span><\/div>\n
Need to find a better solution which doesn\u2019t degrade the crystal filter properties to much.<\/b><\/span><\/div>\n
(By the way, the detector regen. control ads about 4 dB to the AM sensitivity)<\/b><\/span><\/div>\n
The receiver will mainly be used for CW\/SSB reception, so maybe it stays this way for a while <\/b><\/span>J<\/b><\/span><\/span><\/div>\n
<\/b><\/span><\/div>\n
I hooked it up to the W1TS transmitter, which was very loud.<\/b><\/span><\/div>\n
Didn\u2019t foresee a T\/R relay (learned a lot from this project \ud83d\ude09 ), so added this one between the front plates next to the RF and audio gain control.<\/b><\/span><\/div>\n
The quit down everything a little, the RF gain pot is lifted of ground as suggested by James, N2EY at QRZ.com.<\/b><\/span><\/div>\n
It helped a lot, but was still too loud if tuned exactly in the bandpass of the crystals.<\/b><\/span><\/div>\n
The T\/R relay now also switches an adjustable potentiometer at the input of the audio pre-amplifier.<\/b><\/span><\/div>\n
<\/b><\/span><\/div>\n
The dial cord has no lag, and works very well for fine tuning.<\/b><\/span><\/div>\n
Unfortunately the reduction drive went from 1:19 to 1:9\u2026, the tuning capacitor only has a 180 deg. span.<\/b><\/span><\/div>\n
Something to remember for the next receiver.<\/b><\/span><\/div>\n
<\/b><\/span><\/div>\n
It\u2019s a nice little receiver and quite stable after warm-up.<\/b><\/span><\/div>\n
The only extra luxury a next receiver will have, is AGC.<\/b><\/span><\/div>\n
But with no AGC it\u2019s easier to tune the antenna tuner by ear <\/b><\/span>J<\/b><\/span><\/span><\/div>\n
There\u2019s now a complete homebrew station here, antenna, feeder, tuner, receiver, transmitter, power supply, al home made <\/b><\/span>J<\/b><\/span><\/span><\/div>\n
<\/b><\/span><\/div>\n
About the Mystery Hole\u2026.<\/b><\/span><\/div>\n
If you haven\u2019t guessed it by now, or Pete hasn\u2019t told you, it is revealed in one of the pictures below.<\/b><\/span><\/div>\n
<\/b><\/span><\/div>\n
I also made a little video:<\/b><\/span><\/div>\n
<\/b><\/span><\/div>\n
https:\/\/www.youtube.com\/watch?v=4-STxQI36_s<\/b><\/a><\/span><\/div>\n

<\/span><\/div>\n
<\/div>\n
<\/div>\n
<\/a><\/div>\n

<\/p>\n

<\/div>\n

<\/p>\n

<\/a><\/div>\n

<\/p>\n

<\/a><\/div>\n

<\/p>\n

<\/a><\/div>\n

<\/p>\n

<\/a><\/div>\n
<\/span><\/b><\/i><\/u><\/sub><\/sup>
<\/strike><\/div>\n
<\/div>\n