MB8719 with 11.1125 xtal mod

[Techno1]

Has anyone tried these 2 channel mods using the mb8719 and the 11.1125 xtal to get high and low channels.
I know about changing the xtal to the 11.3258 and get the channels.
See the 2 pictures I tried the rotary sw one and would not work with the 11.1125 xtal.
I tried it on a 148gtl NW radio.
They say this mod will work on a Washington/142gtl and radios with the 8719/11.1125 combo.

There is a channel list of the channels u r suppose to get. I again could not get the rotary sw to work.

please let me know what one worked for you.

 

[nomadradio]

The pin 17 mod above is twitchy. The setting of L18 is sensitive to temperature. Not such a big deal for a base radio, but too sensitive to be reliable in a mobile. Quirky and interesting, but potentially unreliable.

73

 

[brandon7861]

The pin 17 mod above is twitchy. The setting of L18 is sensitive to temperature. Not such a big deal for a base radio, but too sensitive to be reliable in a mobile. Quirky and interesting, but potentially unreliable.

73

Yea, twitchy is right. Pin 17 is Fin, not Vcc.

 

[brandon7861]

I remember a mod where pin 10 is brought to some mid rail voltage that allows P6 to be read as high before the internal inverter turns P7 (internal) low (which makes P6 and P7 both high). If this mod uses the Fin bias to achieve that, I would put that directly into the sketchy category.

 

[brandon7861]

I remember a mod where pin 10 is brought to some mid rail voltage that allows P6 to be read as high before the internal inverter turns P7 (internal) low (which makes P6 and P7 both high). If this mod uses the Fin bias to achieve that, I would put that directly into the sketchy category.

Since my washington is already butchered, I decided to try what I said in the above post. Its something I've read about but I cannot remember where. The story goes that floating this pin in the middle somewhere goes high enough to bring P6 high before the internal inverter brings P7 low. I also have a memory of this only being applicable to some of the 8719's, not all of them.

So what happened? On ch1, the radio is on 26.965 until about 3.35v at pin 10. At about 3.5v, the radio changed to 26.325MHz (as expected).

But what about between 3.35v and 3.5v? I expected it to be working at 27.605MHz, but it was out of lock (edit, see next post)

 

[brandon7861]

HOLY CRAP, IT ACTUALLY WORKS!

I couldn't let it go and thought, what if it fell out of lock because the VCO slug was set too far one way. Sure enough, i give that slug a little nudge and BOOM, 27.605 on ch1!!!!! This trick DOES WORK lol