An IC-729 mod : From original two FET mixer to a FET ring doubl balanced mixer

Ages ago I had a chance to service an FT-1000 which belonged to an American ham. I was impressed with the radio and in the course of the service I got to read the schematic and focused on the first mixer. 




I noticed the difference between it and my old IC-729 was it had parralled FETs in the mixer so instead of just two (see IC-729 mixer circuit in the photo), The FT-1000 had a total of four which accounts for its signal handling capability. On a lark, I set out and bought some FETS and thought I would try out the mod. Just before I started construction, I consulted my CQ ferrite core handbook (in Japanese) and saw a circuit for a FET double balanced mixer which promised good strong signal performance as well as gain over the standard diode ring double balanced mixers I have used before in my projects. The only additional part I had to "make" was another transformer for one port. Please see big photo. The four FETs I bought were metal cased. The mod is not too pretty to look at but it works quite well. and of course I give thanks that my rig survived the mod. HIHI

Mga Komento

Mag-post ng isang Komento

Mga sikat na post sa blog na ito

Kenwood HF-50Mhz TRansceiver TS-680V Review Digest

Imahe
Kenwood shortwave 50Mhz base equipment, TS-680V This is the rig that you have purchased a used will want after purchasing a new article, but also I have rung the local after a while. The unit was purchased used. Rather than a full-fledged HF machine, it is an entry-level radio if anything, but it is rig for convenient simple operation. 　In addition, we inherited the traditional TRIO Kenwood sound, even if I have listen for a long time, it is not tiresome to the ear. Device-specific problems are not inherited in the traditional colors of the TRIO walkie-talkie. Model number is also ◎ They discuss pulling the tradition of TS-600. 　It has come in handy and check the band condition, local ragchew, and mobile operation. Condition is excellent for local bands like communication, mobile .... And features To proceed normalKenwood shortwave 50Mhz base equipment, TS-680VKenwood shortwave 50Mhz base equipment, TS-680V, even with the machine of HF, the knob has been placed tig
Magbasa nang higit pa

First "Fun with Morse Code" Inter highschool Contest photos

Imahe
The First "Fun with Morse Code" Inter highschool Contest - Mandaluyong Girl Scout Council with 480 Homebrewers DX1HB. Ten high schools participated. Mandaluyong Science High School won first place.  Congratulations ! True to the contest title, all girl scouts had a Fun day, from fist warm-up to awards ceremony! Icom IC-735 sidetone used as oscillator, VOX off) with German Junker straight key. Photos by Maria Teresa Rdy
Magbasa nang higit pa

Hot-Rod Your ICOM IC-725-Series Transceiver by Jukka Vermasvuori

Imahe
Hot-Rod Your ICOM IC-725-Series Transceiver Part 1  by  Jukka Vermasvuori   OH2GF Receiver Issues The receiver in my IC-725 exhibited these drawbacks: Its audio frequency response was too narrow, dropping 6 dB from its maximum by about 2 kHz. High-end rolloff that is this profound filters out speech energy necessary for good SSB intelligibility and severely muffles AM broadcast signals, which carry audio up to at least 4.5 kHz. 4 The AM-mode audio had a “mega bass” quality. The level of in-band intermodulation products seemed to be quite high. 5 On CW, I could hear weak phantom beat notes from out-of-passband signals. The pitch change of these spurs was the opposite of that of desired signals during tuning. In effect, a strong signal would come back into the receiver passband if I tuned in the right direction. Although these spurious signals were weak, they sometimes disrupted communication as I worked weak DX stations in crowded bands. During CW reception with th
Magbasa nang higit pa