• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

HELP hifi am audio in a cybernet pll02a clone like ge 3-5819a or rca 14t305

kc2koj

Member
Jun 14, 2012
17
1
11
can someone help me out and take a look at this schematic and tell what to change out or to bypass to get fuller hifi tx am audio... looking for loud natural with good range for bass and treble ....what caps should I change or would I be better off trying to inject mic input at a different point ....Thanks ^^ ab v c^^
 

Attachments

  • schematic.pdf
    4.6 MB · Views: 20
  • 14t260_70_14t303_4_5_pg2_pg18.pdf
    3 MB · Views: 12
  • 14t260_70_14t303_4_5_pg19_pg24.pdf
    6.7 MB · Views: 10
  • hygain_2_3_2702_2703_sm_pg01_pg29.pdf
    7.1 MB · Views: 11
  • Midland-77-882-schematic.png
    Midland-77-882-schematic.png
    1.1 MB · Views: 29
  • 14t260_70_14t303_4_5_pg29_30.pdf
    3.8 MB · Views: 7
Last edited:

C94 is what you want to bypass the audio amplifier, your only limiting factor will be the audio transformer.
 
can you please explain .....what should i do ?????? should i pull c94 and just bridge soder points... or inject mic input there... or would i be better off changing value of c94 thanks
 
Last edited:
after looking things over a little more i think you ment inject mic input on + side of c94 if i were to pull i would have no rx sound out speaker right .....anything eles i can change to give better tx audio ..........and on the rx side anything i could change there to make improvements .....anyone with any advice please chime in thanks
 
after looking things over a little more i think you ment inject mic input on + side of c94 if i were to pull i would have no rx sound out speaker right .....anything eles i can change to give better tx audio ..........and on the rx side anything i could change there to make improvements .....anyone with any advice please chime in thanks

You want to inject to the negative side of the cap.

Yes it looks like you lose RX, might need a relay.

Improving RX would be a chore, you also still limited on TX and RX by the audio transformer.
 
You're almost better off getting a Cobra 148 or Grant XL, You can make improvements on this radio but not much.
 
so, just a disclaimer, ive never done this to this chassis before, but it looks to me like these changes would help:

C80- .001uF (TX)
C81- 1uF (TX)
C83- 1uF (RX and TX)
C82- 100pF (RX and TX)
C75- .47uF (RX)
C94- 470uF (RX and TX)

joedirt is right about the audio transformer choking the bandwidth, but you should still notice some improvement.

the parts values i chose for the changes are just guesses.
the changes should be done one at a time, and the effects noted.

the general rule is to increase the series capacitance and decrease the parallel capacitance, which is what ive done in the changes i suggested.

for example, i chose 1uF for C83. you may find that this is way too bassy, and you might want to try a .47uF, or maybe even a .22uF capacitor.

one thing to note here is that electrolytics should not be your first choice.
ceramic and mylar caps are better for audio tailoring.

good luck, and please do post your results for the benefit of others who my run across this thread in the future.
LC
 
kc2koj said:
joedirt said:
You lift the - leg that connects to the audio amp and inject your outboard audio into the lifted leg of c94. You might need to remove the cap and install a larger one for better low end response.

Just changing the value of c94 alone will not be enough, there are many other limiting factors to your TX bandwidth than just that one cap but that cap is the last one inline before the modulation stage so you will just save yourself a bunch of time just feeding c94 with outboard audio
one might ask why do this to this radio and i would say they have good rx and a pll02a chip they can be bought for 10-20 dollars on ebay.... i have a great radio for ssb but that radio has bad am tx...
thanks guys im going to change out some caps and post results ....
 
  • Like
Reactions: Chris Wells

dxChat
Help Users
  • No one is chatting at the moment.
  • dxBot:
    Tucker442 has left the room.
  • @ BJ radionut:
    LIVE 10:00 AM EST :cool:
  • @ Charles Edwards:
    I'm looking for factory settings 1 through 59 for a AT 5555 n2 or AT500 M2 I only wrote down half the values feel like a idiot I need help will be appreciated