EP 075 - HAM International Jumbo MK1 - FM Audio mod and and more essential work- Part 3

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EP 075 - HAM International Jumbo MK1 - FM Audio mod and and more essential work- Part 3
FM audio mod , some alignment and essential work.
NOTE in the video i mention C3 to remove , actually its C30 ;)

[@keesbaaij8003]

You mentioned to remove C3 for FM-audio mod. Should be C30. ;-)
Great videos for this Jumbo allignement and mods. Tnx.

[@MicroChipz]

you are correct , my mistake in the voiceover. thanks for noticing .

[@andyward7272]

The FM audio is more noticeable when your tuned down from the centre frequency because at that point the crystal is over worked once modded it sounds perfect
Peaking The RX I find is best done with the meter or Sinad meter and use the scope for correct adjustment of the Quadrature coil
Remember to change C11 560P as a preventative measure it’s known to go short and kills the 10.240 oscillator shutting down the set when warm

[@MicroChipz]

I'm sure that's one of the first things i did, maybe didn't film it .I was just messing with the " service manual " way of alignment ,

[@paullucas4791]

For the squelch pop the way i've done it has been on Q33, a 16V 10uF electrolytic from the centre leg to the pcb earth, mounted top side. And obviously use the corresponding transistor on the other cybernet pcb variants that goto pin 7 on the audio chip.

[@MicroChipz]

Thanks for the info

[@markherbert6737]

Hi there, It would be super helpful if you shared the circuit diagram showing the mod so we could see how this mod is applied to other similar chassis sets. I have a couple of these vintage family radios.
Your other vids are really interesting too, but I'd love to see where the work is on the schematic to give it some context.
All the best

[@MicroChipz]

Check out cubwolf fm audio mod for ham , there is'nt really a diagram for the mod .cubwolf.wordpress.com/2015/02/25/ham-international-jumbo-multimode-2-modifications/

[@MicroChipz]

Basically on this board the fm audio comes from modulating the crystal, this mod isolates this and uses another varicap diode to produce the fm audio and feeds it into the mixer.

[@martin.rus.]

Hello MicroChips, I have a question regarding the signal generator you are using for this video. I know you can buy it at Ali, but the question is, is it good enough for these type of measurements? Martin

[@MicroChipz]

if you need a quick signal source that is adjustable , and it has a 1k tone so can be scoped, yeh its worth it , obviously its comparable to a professional test set , but it works.

[@bazparker51]

I alway thought the FM mod
was for the transmitted audio?

[@MicroChipz]

It is I was monitoring on another radio

[@bazparker51]

@@MicroChipz oh I see great vid BTW

[@MicroChipz]

Thanks

[@mikeyf103]

Can you think of a beneficial mod for this stalker

[@MicroChipz]

Not really .

[@mikeyf103]

Always sounded wolly on these Ham International radios the fm modulation

[@MicroChipz]

Not with my VCO in , they sound sweet now.