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President Jackson Tuning tips?

S

skirtchaser

Active Member
Sep 18, 2005
122
4
28
N.Western Arizona
Hi then and hello again,
What is the deal with these things? The squelch is like an unforgiving mother in law (abrasive cut off and cut in) decent receive though. Perhaps Im' just used to the smoothe roll in and out of my Grant XL. Also the noise blank......is this thing even functional in these rigs? Any ideas on how to correct these issues?
I'm really digging the thing though, CB Bible mod to the TX section has this thing keying 2 (AM) watts swinging up to 17 looking almost perfectly symmetrical on the scope (seems to keep the old disco final happy, its nice and cool) I'm running it through a four X 1446 amp its doing a 75(AM) watt key swinging up to 320 on the hi setting.
Great sideband performance as well, I can see why these things were (are?) quite popular
 

freecell said:
"10 watts in gets you 100 watts out........"

maybe at 50 MHz., not at 27........

footnote: the Cobra XL500 produces 475WPEP Output with 22WPEP Input using 4XSD1446/MMQ.
Click to expand...
beter yet, its 110 at 30 MHz not 50 MHz
so over 100 at 27 Mhz depends on how the amp is wired and your vswr

1446

and voltage don't change the gain...lol ya right...I guess equipment is wrong :p
but your write about it taking 2 to make it right though :p


anyways skirtchaser theres your info take it as you wish!
enjoy!
 
let me explain it to you again YFM, 10W in does not get you 100W out at 27Mhz. furthermore, 10W into a single SD1446 @ 27 Mhz. constitutes excessive drive as the collector current has long since quit tracking the base current at that point. at 90W out the 1446 is already 1 - 1.5db. into the compression curve (an important parameter in am and ssb transmitters utilizing asymmetrical (human voice) audio waveforms (linear amplifiers) ) and the gain of the transistor is steadily reduced from there on....due solely to excessive drive. while 10W in might be acceptable (7W is spec.) in cw/fm operation @ 50 Mhz. since no asymmetrical waveforms are present in those modes and the typical device gain is approximately 10db. the gain of the 1446 increases by slightly better than 3db. when operated at 27 Mhz.. at the reduced frequency the 1446 becomes more drive sensitive requiring less drive to produce the same power output.

50 Mhz.
dbgain = 10log(POut/PIn)
dbgain = 10log(70/7)
dbgain = 10log(10)
dbgain = 10(1)
dbgain = 10

27 Mhz.
dbgain = 10log(POut/PIn)
dbgain = 10log(90/4.5)
dbgain = 10log(20)
dbgain = 10(1.301)
dbgain = 13.01

coupled with the fact that the 1446 is available in six different Hfe/Beta flavors from J to O Beta Codes provides a range of devices offering increasingly better gain figures depending on the ability of the amplifier circuitry to remain stable under the conditions demanded by the particular application in use.

Generally speaking, RF power gain (Pg) and Maximum Saturated Power Output (Po) will be higher with "High Beta" parts, however, amplifiers will tend to be less "rugged" and may require additional stabilization.

ST Micro Electronics
Beta Cross Reference

Letter Code
J.....70-80
K....80-90
L....90-100
M...100-110
N...110-120
O...120-150

http://rfparts.com/tranmatch.html

only extremely well built and designed amplifiers can function dependably with devices in the higher end of the beta code range. as a matter of fact the genuine palomar 225 uses the O beta code devices in matched pairs, just one example. the Cobra XL500 uses the M beta code devices to maintain stability across the entire operating frequency range of the amplifier.

there's some information worth having.
 
(beavis face) uuuhhhh.... Yea....Huh Huh......
I'm ok with my TX output, even though my old para dynamics meter is not particularly accurate anymore (if it ever was! LOL)
More is not really better, at the expense of reliability, in my experience. And unless I'm wrong, that about where the Palomar 400 I'm using should be operating at.(I know it sounds really good at those levels)
My issiue is with the squelch being so harsh, it's almost like the 2510, and the noise blanker seems to have zero affect in this unit.
I like to set my rig up by turning the RF gain all the way up then I roll up the squelch until the signal gets cut off. Then I roll it back just a touch to get the signal back, then I roll down the RF gain until the signal cuts back out again and I leave it that way to go down the road. That works quite well on my Grant but on the Jackson doing the same thing requires rolling the RF gain down a long way to cut the signal back out then the cut in is stuttery (a technical term stuttery is....) on recieve. in out in out following only the peaks in a received signal . Irritating at best. And I'm used to turning off the noise blanker to cut out bleed over from other channels on my grant, but I leave it on to control noise otherwise. This unit's blanker seems to have no affect at all, on or off in either usage.
 
"keying 2 (AM) watts swinging up to 17........"
"I'm running it through a four X 1446 amp its doing a 75(AM) watt key swinging up to 320 on the hi setting."

PIn = 17W, POut = 320W.

dbgain = 10log(POut/PIn)
dbgain = 10log(320/17)
dbgain = 10log(18.823)
dbgain = 10(1.274)
dbgain = (12.747)

your measurements indicate that the transistors are still being driven properly and providing sufficient gain while still maintaining a high amount of linearity.

as for your "stuttering" squelch anomaly, the grant xl uses hysteresis based circuitry and the jackson doesn't. i'm sure you've already thought of the obvious "dirty control".

documentation for the jackson dx is sparse so it's difficult to point you anywhere for the noise blanker info. i'll dig around and see if i can find anything. if it's in the portal i can email it to you. cbtricks has nothing on the jackson dx.

if it was in front of me i could handle it. i'll see what i can find.
 
OK, so i looked up "hysteresis" and relative to the circuit, I understand what that entails, explaining why the Grant has the ability to break open the squelch on a peak and stay open throughout the transmission (within reasonable levels) then close again.
What other type(s) of circuitry is/are used to provide the functions, and why is the 148 / Grant Xl so unique in this aspect.?
 
So why was the concept not continued throughout another platform? Is it expensive, labor intensive related to construction? What?
PS: why aren't you accepting new members to the forum?
 
the jacko is in lou franklins uniden export manual,

some of the circuit is very similar to the lincoln,

do the ssb agc timing mod,

check that nobody has changed the filters in it, if they change the wrong one the blanker wont work nearly as effectively as it should.
 

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