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Mixer IC I think
- Thread starter Smokinone
- Start date
Preferably. There is a good quarter watt going through it, so be sure to get something rated at 1w for better heat dissipation. Half watt will suffice if its all you have (but it will live its life on the warmer side).
No problem, just find 2 (equally well rated) diodes with forward drops close to .5v and add them in series.
Edit: My4148's 4007's (sorry) from mouser are just under .6v and that might be close enough. Dont want to be too far from 9.6 otherwise bias points that use that regulated voltage elsewhere in the radio will be wrong and who knows what will happen. If we are lucky, that will be the reason it don't work.
Edit: My
Back to that VR1 in the SC you turned... Had time to think about it.
If that PLL is anything like the PLL from the 621 (which it has already shown similarities to), I would guess that the VR is in series with the emitter bypass cap on the VCO buffer as a means to control its gain. That gain adjustment will affect the behavior of the mixer in the PLL loop. The mixer needs a specific drive level, but give it too much and IMD products are produced. It would probably take a SA on the input of the BPF before the divider to set properly.
Although I do admit, before I knew what that did, I had got a royce working decently setting it about mid range.
The notes on my PLL schematic show what little I knew when I traced that bugger out lol, and that wasn't all that long ago!
If that PLL is anything like the PLL from the 621 (which it has already shown similarities to), I would guess that the VR is in series with the emitter bypass cap on the VCO buffer as a means to control its gain. That gain adjustment will affect the behavior of the mixer in the PLL loop. The mixer needs a specific drive level, but give it too much and IMD products are produced. It would probably take a SA on the input of the BPF before the divider to set properly.
Although I do admit, before I knew what that did, I had got a royce working decently setting it about mid range.
The notes on my PLL schematic show what little I knew when I traced that bugger out lol, and that wasn't all that long ago!
I think it would work, but if you don't mind sticking leads on a surface mount part, there is one with a closer voltage (9.65) rated at 1w
www.digikey.com
maybe a little scrap of board cut from a spot with parallel traces that can accommodate both the part and leads.
KDZVTFTR9.1B | Digi-Key Electronics
Order today, ships today. KDZVTFTR9.1B – Zener Diode 9.65 V 1 W ±6.04% Surface Mount PMDU from Rohm Semiconductor. Pricing and Availability on millions of electronic components from Digi-Key Electronics.
maybe a little scrap of board cut from a spot with parallel traces that can accommodate both the part and leads.
I think it would work, but if you don't mind sticking leads on a surface mount part, there is one with a closer voltage (9.65) rated at 1w
KDZVTFTR9.1B | Digi-Key Electronics
Order today, ships today. KDZVTFTR9.1B – Zener Diode 9.65 V 1 W ±6.04% Surface Mount PMDU from Rohm Semiconductor. Pricing and Availability on millions of electronic components from Digi-Key Electronics.
maybe a little scrap of board cut from a spot with parallel traces that can accommodate both the part and leads.
I can barely work with 1/8 watt resistors my friend...I'm using this now:
And with my fat and old shaky hands...
I think I need to go with something a little bigger although it's a good idea.
That's what I need at my desk!!! I have a plastic cheap version that is falling apart and wont stay where I put it.
yeah, I had a lesser quality one, the kind from overseas, and it had issues as well. Found the one I have on the bay, industrial quality, and it looks cool. Not quite as old as me, but close
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