Wierd one this.
Bloke gave me a 148 to play with, basic line up and add a UK when done.
He reckoned he could hear nobody.
Well he wouldn't a 25 Mhz!
There is problem around 145106, adders are getting correct codes from band switch, and frequency spacing is correct through each band, so channel switch appears ok.
Here's the strange bit.
VCO voltage is correct as per manual, but radio is 680khz low on low and Hi, but 730khz low frequency on mid
Adders seem to be doing what they should, PLL is doing correct spacing and locked.
I must be honest, although I have done dozens over the years, I am a bit rusty, so any ideas accepted.
Also, has anybody tried those chinese 145106 ICs,
148 Mk2
- cb4ever104
- Legend
- Posts: 6561
- Joined: 28 Jul 2011, 21:26
- Location: España
Re: 148 Mk2
Time to get the service manual out and go through the pll and oscillator section. Have a look at TP3 with the counter and see what's going on. Adders might be ok , but what about the channel selector ? There's a few things that could be wrong , but I'd start with the mk2 manual.
Sammy
Sammy
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
-
- Super Member
- Posts: 273
- Joined: 04 Jun 2012, 18:11
Re: 148 Mk2
Wrong reference crystal, and wrong core in VCO.
Quite why the hell somebody would change a 15.000 for a 14.31818 is beyond me, unless they couldn't be bothered to find the correct one of course.
Now to try and align it, but being very wary, as I do not know what may have been done previously
Quite why the hell somebody would change a 15.000 for a 14.31818 is beyond me, unless they couldn't be bothered to find the correct one of course.
Now to try and align it, but being very wary, as I do not know what may have been done previously
- 13EL121
- Radio Addict
- Posts: 618
- Joined: 16 Sep 2008, 20:55
- Call Sign: 13DA121
- Location: Germany
- Contact:
Re: 148 Mk2
Best way is to swap the xtal to an original UNI 15.000.
I had some tests with other xtals. They dont work well. The coarse Clarifier only slides 2-3kc with non original ones. They are “harder“ to pull on frequency. But they are more stable, so less drift.
I had some tests with other xtals. They dont work well. The coarse Clarifier only slides 2-3kc with non original ones. They are “harder“ to pull on frequency. But they are more stable, so less drift.