Tuesday, June 1, 2021

Regarding the tuner problem

It ts very possible htat in this list non known that I m 50 years DXer. Indeed I started with a radio in my hands 59 years ago playing with my fathers  morse keyer

Let me go direct to the case . I know much of the thory since the 80s and had two volumes of the ARRL book and later bought the ARRL antenna handbook. On 80s and litle lter i have made a few hand made things with a Antenna preselector using just a LC circuit  that was by two capacitors and one coila mde from a ....toilet paper with around 25 wounds of wire . It worked very well untill on mid 2000it shown problems if tuning 

I then gave that to a radio amateur who totaly redesigned adding a lot of swtches and connectors that tuend into a totally ... useless ATU 

 

 

This guy  kept the original plastic case.This is the original part drilled by me .The toilet paper was thinner in my design The C is the original cap and the L has been changed to multi switch The above is a twin cable coil. 


I Used  the inside  of the toiler paper to tune my radios by just putting their antennas. 

In the above picture he added two RCA type plugs that connect with a typical RCA-stereo plug jumper 

Now please open and study the above  photo . The switch has more than 15 positions . For me this design goes to a mess to nowhere 

M original design was much simpler and more operative : Both knobs were operative with two var capacitors , the one as shwon in the photo (around 450pf? ) and another in the switch position of around 160 pf air type . An original Π or PI type

The coil was  near the same size and kept in the opposite side of the knobs . it was wound with one only cable to around 25 turns and trapped in irregular points with small wire. The wire was connected ionto a wire with alligator clips from the one end of the two capacitors 

Now it the time that I am unwilling to restore this design to its original format not only due to finger inability but also to the poor mood .. 

I also already know that the Chinese have aleady redesigned  the MFJ 1026 into a 1/4 of the price

Why not redesign any antenna tuner or preselector that is much cheaper to design ? 

The only posible way for the moment is double tinkering an older preselector the old 1050 B . its main FET was burned from lightning more than 20 years ago tested then by another radio amateur who enhanced its operation but the 'burnout' still  exists with strong carriers nearby the Q's centre ! 

The only idea for that is just isolate all the active parts of this preselector (MFJ 1040B ) and use it as passive  inside its box with minimal experiments. Good idea bu not for me even if i  can understand onhow it can be done. Fingers are quite fat for that but: I stopped very long to do hardware work.

Now the problem is even bigger . The local technician prefers to do the easy way of  just replacing ready circuits boards instead of lab testing the problem  and using stickers and soldering how more top start opening holes etc

As for a few examples of the past , 

1.he was totally unable to find a stylus and the rubber for a turntable I inisted 3 times but finally he didn't do anything That happened more than 10 years ago.

2.by [verbal] force he restored the cable of sennsheiser heedphone HD497 aftet it was cut by indeliberate shock , After the service  an echo was produced hich irritates my head

3. an older mini radio was not restored because he could not find a mini screw 

4. rejected to service 2 degen 1102 radios. Battery compartment problem.These radios now  work only with their external adaptors! 

5. he asked me to litter  a K44 AKG headphone because the connectivity was unusual as he said. hat happened on pre10

The same happened with a computer technician who only preferred to help  with just opening and cleaning some gear . He also stopped soldering but only testing and repairing PC gear in both software and hardware parts !

These two "electrician engineers" cant for sure be called as engineers by the terms of older times!


No comments:

Post a Comment

Top posts