Deleted
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Post by Deleted on Jan 9, 2009 21:31:34 GMT -5
It is amazing how I end up with some of this junk. So dude game me a whole bunch of junk mobile. Funny this is, I did not want them. But the guy insisted, so I too them. I threw out some and scrapped others. I kept this one. It appears to DK 4 watts, and swing upwards of 12 watts. A couple problems.
1. I need the wattage adjustment pot for the S meter, as it does not move in transmit.
2. The trasmit frequency is off. Being is not PLL, is there an adjustment for this? I am measuring 27.182 on channel 19 (should be 27.185).
I figured if this works, I can dump it for money for my parts fund. I do not want to spend much time on this as I didn't want it in the first place.
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Post by mrgumby OT21 on Jan 9, 2009 22:04:07 GMT -5
thats pretty close at 182 some of my old crystal radios are off a little bit more
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Post by Deleted on Jan 9, 2009 22:09:20 GMT -5
3K Hz off is pretty close? Ouch. No wonder crystal radios went into the crapper.
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Sandbagger
Administrator/The Boss 
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Post by Sandbagger on Jan 9, 2009 23:26:44 GMT -5
It is amazing how I end up with some of this junk. So dude game me a whole bunch of junk mobile. Funny this is, I did not want them. But the guy insisted, so I too them. I threw out some and scrapped others. I kept this one. It appears to DK 4 watts, and swing upwards of 12 watts. A couple problems. 1. I need the wattage adjustment pot for the S meter, as it does not move in transmit. 2. The trasmit frequency is off. Being is not PLL, is there an adjustment for this? I am measuring 27.182 on channel 19 (should be 27.185). I figured if this works, I can dump it for money for my parts fund. I do not want to spend much time on this as I didn't want it in the first place. Well, the Tram Diamond 40 is an AM-only mobile rig, so there usually isn't a means to adjust individual crystals. Usually only SSB rigs (which need more uniform an closer frequency tolerance for SSB use) have trimmers on the crystals. You'll have to either do one of two things. Either replace the crystal, or try to "pad" the crystal by adding your own trimmer in series with the crystal. And as a BTW, if channel 19 is off, chances are that either 17, 18 and 20 are also off or 3,7,11,15,(22A) will be off instead. And depending on which set of frequencies is off, will determine which crystal is bad. CBtricks doesn't have the schematic for the D40, and I don't have it in my dog-eared files either, so you'll have to check the pots one by one to find out which is the RF meter adjustment.... |
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Post by Deleted on Jan 11, 2009 9:46:11 GMT -5
Dave,
I think the frequency is off by that much on all channels. I have some scrap radios with 23 channels.
Funny, but this guy is the guy that keeps giving me his junk. I simply went their to borrow a Galaxy Saturn service manual so I can align the PLL on one of those for a friend. He kept me there 1 hour, handing me this crap and that crap (all junk). I know it's junk, because he has Cobra 2000 and 142 there, and won't give them up, even though there are in pieces.
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Sandbagger
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Post by Sandbagger on Jan 11, 2009 11:41:38 GMT -5
Dave, I think the frequency is off by that much on all channels. I have some scrap radios with 23 channels. Funny, but this guy is the guy that keeps giving me his junk. I simply went their to borrow a Galaxy Saturn service manual so I can align the PLL on one of those for a friend. He kept me there 1 hour, handing me this crap and that crap (all junk). I know it's junk, because he has Cobra 2000 and 142 there, and won't give them up, even though there are in pieces. Well if ALL the channels are off the same amount then there is probably a bad cap or something pulling the oscillator off, or someone had their fingers in it trying to make it "slide". The receive mixer oscillator has an adjustment (L1) but there is nothing for the transmit. I couldn't find the schematic of the D40 but I'm pretty sure the Browning SST was its twin brother and that schematic can be found on CBtricks here: www.cbtricks.com/radios/browning/sst/graphics/browning_sst_sm.pdf |
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Post by Deleted on Jan 11, 2009 12:19:05 GMT -5
There is a channel mod with a switch and 2 crystals. However, the transmit freq does not change with the switch in either position. This one my be headed for the scrap heap.
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Post by Tombstone (R.I.P.) on Jan 11, 2009 14:37:17 GMT -5
Hmmm. There's a start. You could remove the channel mod and put the radio back to stock and see if you get any closer to frequency. No doubt that when the mod was done "adjustments" were made. Like Sandbagger says, there could be something effecting the oscillator. I think that there's a main mixer crystal in there too and that might be off a little. Just all guesses, good luck.
Tombstone
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Post by 2600 on Jan 11, 2009 23:41:56 GMT -5
Too lazy to look it up, but I remember a 12 MHz crystal, more or less, that would move all 23 channels if you changed it.
Long wires to a switch will usually cause the frequency of a crystal to run too low.
Could be that moving the crystal for normal channels back to the 2 holes in the pc board will fix this.
If the receiver is ALSO off frequency, the channel mod is most likely the source of the trouble. Especially if the wires to the "mod" switch are very long.
73
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