| Author |
Message |
    
Onespeed
New member
Username: Onespeed
Post Number: 2
Registered: 9-2004
| | Posted on Friday, September 10, 2004 - 12:53 am: | 
|
What are some good mods for this radio? |
Northernherb
New member
Username: Northernherb
Post Number: 1
Registered: 10-2004
| | Posted on Friday, October 08, 2004 - 5:53 pm: |
|
I also own this awesome radio, heard it has great potential for tweaking.... |
Tech548
Moderator
Username: Tech548
Post Number: 314
Registered: 5-2004
| | Posted on Wednesday, October 13, 2004 - 11:56 pm: |
|
Onespeed
This modification will make you PC-68 scream.
PC-68 Swing Modification
--------------------
These modification will allow you to easily drive a linear without "over-driving" it. This will also work for the Cobra-25/29. Be sure the radio has been peaked before doing this modification.
-------------------------
Parts needed:
1- 220uF (16 to 25 volt) electrolytic capacitor.
1- 200 ohm resistor (which will give you a 1/2 watt deadkey) or a 400 ohm resistor (which will give you a 1 watt dead-key).
If you will notice, the higher the resistance, the higher the dead-key will be. Personally, I recomend a very minimum of at least a 400 ohm resistor because that will key just about any linear without a problem. You can experiment with different values until you get the desired dead-key.
Note: 1 to 1.5 watts works best for keying linears. Anything over 1.5 pretty much defeats the purpose of this modification when used with a linear.
---------------
Here's how to do the modification.
1- Unsolder JP-6 found near the final.
2- Solder the 220uF capacitor in the now empty holes where the jumper was removed. Take note that the negative side of the capacitor faces the final.
3- On the printed side of the board, solder a 200 to 400 ohm resistor across the solder joints of the newly installed 220uF capacitor.
Remember now, the higher the resistor value, the higher the dead-key will be. Don't be afraid to experiment with different values until you get your desired dead-key.
In order to make your power "VARIABLE", mount a 5-10K ohm variable control knob in a convenient location in place of the "fixed" resistor.
Jeff
Tech548 |
Beeker7104
New member
Username: Beeker7104
Post Number: 1
Registered: 12-2004
| | Posted on Saturday, December 25, 2004 - 7:58 pm: |
|
Where is the limiter located on the board of the radio? on the pc 68 xl/elite |
Doublemm
Junior Member
Username: Doublemm
Post Number: 26
Registered: 5-2002
| | Posted on Tuesday, March 29, 2005 - 11:45 am: |
|
for this pc 68 does anyone have the varible adjustment info for this radio. main vr number i need is for the squelch adjustment. thanks. |
Vanillagorilla
Junior Member
Username: Vanillagorilla
Post Number: 20
Registered: 4-2005
| | Posted on Tuesday, April 26, 2005 - 9:12 am: |
|
I imagine I'm too late to help here but here goes:
VR-1 = S meter cal/adj
VR-2 = Squelch Range
VR-5 = AM Mod
L-19 = Noise blanker (if equipped)
As a side note I did the same swing kit 548 listed above for my mobile PC68LTW. That thing IS a screamer now! D/K about 1w and swings to 27w!
DO NOT clip the mod limiter for this mod. Turn up VR-5 and do the cap resister mod as per Jeff and you'll be very happy!
Thinking back I do recall having to back L-10 amost all the way out to break the 10w swing into the magic zone.
Good luck!
Hank "905"
LI New York |
Doublet246
Junior Member
Username: Doublet246
Post Number: 11
Registered: 12-2002
| | Posted on Sunday, July 02, 2006 - 9:11 pm: |
|
what is the limiter # on the 68XL? |
Moonraker
Intermediate Member
Username: Moonraker
Post Number: 229
Registered: 3-2005
| | Posted on Monday, July 03, 2006 - 7:12 pm: |
|
I beleive it is D9. The radio is the same as a cobra 25 so all the adjustments are the same.
You can turn up vr5 to get the modulation. I wouldn't cut the limiter, but if you must... |
Doublet246
Junior Member
Username: Doublet246
Post Number: 12
Registered: 12-2002
| | Posted on Wednesday, July 05, 2006 - 2:36 pm: |
|
548 there is no jp6 in my 68XL theres a jv 17 near the final?
this radio is made in china and it is not the same as the cobra 25 or 29? |
Moonraker
Intermediate Member
Username: Moonraker
Post Number: 230
Registered: 3-2005
| | Posted on Wednesday, July 05, 2006 - 9:56 pm: |
|
look at the final, right in front of it you will see a jumper that is about 1/2 inch long. It doesn't say jp6, but its what your looking for.
Also the mod above says "Remember now, the higher the resistor value, the higher the dead-key will be."
That is not correct. The more resistance you have, the lower the key will be. When the jumper is in place you have no resistance and the full dead key. The purpose of the resistor is to lower the dead key.
I like to use a 35 volt 470uf cap, the higher voltage is not required and doesn't give you more power but overkill is a good thing...to an extent. |
Doublet246
Junior Member
Username: Doublet246
Post Number: 13
Registered: 12-2002
| | Posted on Thursday, July 06, 2006 - 12:50 pm: |
|
moonraker there is a choke and a res. in front of the final no jumper in front at all. i think this is a newer radio than the one that is talked about on this page? |
Moonraker
Intermediate Member
Username: Moonraker
Post Number: 232
Registered: 3-2005
| | Posted on Thursday, July 06, 2006 - 7:52 pm: |
|
The pc 68 XL I have is made in the philippines. Never had a china model... |
Doublet246
Junior Member
Username: Doublet246
Post Number: 14
Registered: 12-2002
| | Posted on Saturday, July 08, 2006 - 1:43 pm: |
|
the jumper is jv17 on the china made 68XL same mod as above. |
Kpoe_28
Junior Member
Username: Kpoe_28
Post Number: 24
Registered: 1-2005
| | Posted on Wednesday, May 09, 2007 - 7:14 pm: |
|
Will this mod work on the Cobra 25LTD?
Thanks,
kevin
Posted on Wednesday, October 13, 2004 - 11:56 pm:
--------------------------------------------------------------------------------
Onespeed
This modification will make you PC-68 scream.
PC-68 Swing Modification
--------------------
These modification will allow you to easily drive a linear without "over-driving" it. This will also work for the Cobra-25/29. Be sure the radio has been peaked before doing this modification.
-------------------------
Parts needed:
1- 220uF (16 to 25 volt) electrolytic capacitor.
1- 200 ohm resistor (which will give you a 1/2 watt deadkey) or a 400 ohm resistor (which will give you a 1 watt dead-key).
If you will notice, the higher the resistance, the higher the dead-key will be. Personally, I recomend a very minimum of at least a 400 ohm resistor because that will key just about any linear without a problem. You can experiment with different values until you get the desired dead-key.
Note: 1 to 1.5 watts works best for keying linears. Anything over 1.5 pretty much defeats the purpose of this modification when used with a linear.
---------------
Here's how to do the modification.
1- Unsolder JP-6 found near the final.
2- Solder the 220uF capacitor in the now empty holes where the jumper was removed. Take note that the negative side of the capacitor faces the final.
3- On the printed side of the board, solder a 200 to 400 ohm resistor across the solder joints of the newly installed 220uF capacitor.
Remember now, the higher the resistor value, the higher the dead-key will be. Don't be afraid to experiment with different values until you get your desired dead-key.
In order to make your power "VARIABLE", mount a 5-10K ohm variable control knob in a convenient location in place of the "fixed" resistor.
Jeff
Tech548 |
615_ri
Junior Member
Username: 615_ri
Post Number: 42
Registered: 5-2006
| | Posted on Thursday, May 10, 2007 - 8:39 am: |
|
do you know what resistor d11 was in my cobra 29? |
