We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissible in your locale.

Author Topic: what would make a box not like certain crystals?  (Read 3832 times)

Offline moof

  • Full Member
  • ***
  • Posts: 223
    • View Profile
    • Email
what would make a box not like certain crystals?
« on: May 21, 2016, 1817 UTC »
Let's say I have 2 grenade style boxes and x number of WWII crystals all the same frequency. All work perfectly in box #1 with close to 10 watts from the IRF510.  In box #2, half are associated with power close to 10 watts, half get anywhere from a couple needlewidths of power to about 1 watt.  Any suggestions of what components to mess with?  About all I can guess to start is mess with the nice mica caps right before the antenna output and see if jacking around the values +/- 50-100 pF fixes things for the bad crystals yet makes the good crystal output suffer a bit.  I already optimized those when I built the boxes.  Theoretically speaking.

Offline Stretchyman

  • Hero Member
  • *****
  • Posts: 655
    • View Profile
Re: what would make a box not like certain crystals?
« Reply #1 on: May 23, 2016, 1448 UTC »
The osc section of box 2 sounds dodgy.

Do you have a 'scope?

Having one would be most useful.

Str.
'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

Offline moof

  • Full Member
  • ***
  • Posts: 223
    • View Profile
    • Email
Re: what would make a box not like certain crystals?
« Reply #2 on: May 23, 2016, 2307 UTC »
No.  Don't have a couple hundred bucks laying around and don't have much of an electrical background.  Read some books and figured stuff out.
So check connections and component values with multimeter where possible I guess in the oscillator area.  Maybe try to replace a few bits I can't test.
Thanks for input.

Offline Stretchyman

  • Hero Member
  • *****
  • Posts: 655
    • View Profile
Re: what would make a box not like certain crystals?
« Reply #3 on: May 24, 2016, 0637 UTC »
Get a 'scope, you don't need an 'Electrical Background' but you will be able to 'See' what's going on.

What you're dealing with is invisible!

 ;)
'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

Offline redhat

  • DX Legend
  • ******
  • Posts: 1585
  • USA
  • Music is my drug.
    • View Profile
    • Email
Re: what would make a box not like certain crystals?
« Reply #4 on: May 28, 2016, 0257 UTC »
Sounds like box # 2 has a weak oscillator transistor, or something isn't right on the crystal loading side.

...Also something I wouldn't tackle without a scope.  I've been using one for so long, I can't imagine not having one.


Good luck grasshopper!

+-RH
Somewhere under the stars...
Airspy HF+, MLA-30/Mini-whip/Chi-Town Loop
Please send QSL's and reception reports to xfmshortwave [at] proton [d0t] me