Do you tune one side for CH40 and one for CH1 or both on the middle of your band?
How do I balance it between 1 and 40?
How do I balance it between 1 and 40?
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How to properly tune L4 on Uniden 858
- Thread starter 357
- Start date
Ya it just says tune on 19 but I seen places the say tune one side high, one side low-same with TX L37 or in my case, L24
i have never seen any other info than what is in the service manual. for the 858 washington radios. I have 3 of them I recapped and aligned 2 years ago. I aligned them per the service manual and never went by some ones roomers. i have only been working on radios since 2000 so may be some older guy's that will have a different answer for you.
so any way the service manual worked for me.
so any way the service manual worked for me.
IMO it doesn't matter which one you tune for channel 1 and which one you tune for channel 40.
I have done quite a few, and never noticed a problem regardless of which was tuned to what.
now, that being said, there are guys on here who make me look like a newbie when it comes to the 858 chassis, and their advice should be heeded if offered.
As far as how to balance them, first peak the receive coils on 19 like the service manual says.
then use your sig gen on the lowest channel, and the highest channel using the exact same microvolt level of input.
note the differences in the S meter readings, and adjust the cans in L4 to balance the readings.
it shouldn't need much, probably a slight tweak on each coil will balance the receive gain.
you can do this with L37 on TX also.
LC
I have done quite a few, and never noticed a problem regardless of which was tuned to what.
now, that being said, there are guys on here who make me look like a newbie when it comes to the 858 chassis, and their advice should be heeded if offered.
As far as how to balance them, first peak the receive coils on 19 like the service manual says.
then use your sig gen on the lowest channel, and the highest channel using the exact same microvolt level of input.
note the differences in the S meter readings, and adjust the cans in L4 to balance the readings.
it shouldn't need much, probably a slight tweak on each coil will balance the receive gain.
you can do this with L37 on TX also.
LC
Thanks LC and Sonoma.
Honestly what I've been doing is tuning up on 25 the going to the highest I got, 605 I think and going to L4 or L24 aka L37 and finding which side responds more, the tune it for peak then drop to 1 and tune the other side.
That really worked good on tx for me.
Right now when I tune the recive for peak, I'm getting a very low signal to noise and get a "crackle" on the peaks.
Its like I have a noisy transistor in the rf chain.
When I got this radio, it had no recieve cause the af amp was toast.
I think a few people or at least one gave them all a tweak maybe.
Honestly what I've been doing is tuning up on 25 the going to the highest I got, 605 I think and going to L4 or L24 aka L37 and finding which side responds more, the tune it for peak then drop to 1 and tune the other side.
That really worked good on tx for me.
Right now when I tune the recive for peak, I'm getting a very low signal to noise and get a "crackle" on the peaks.
Its like I have a noisy transistor in the rf chain.
When I got this radio, it had no recieve cause the af amp was toast.
I think a few people or at least one gave them all a tweak maybe.
Found it. C63 (tantalum) is on the back of the board on the 40D.
For some reason I had a .1uf and the schematic and part list say 4.7uf.
I eliminated the "crackle".
I tuned on 30 the first this time on SSB but tuned FT1, L28,L29 on 19 cause no AM up top.
After that for L4, I tuned the yellow side on 27.605 and the black on 26.965.
Even across the band.
For some reason I had a .1uf and the schematic and part list say 4.7uf.
I eliminated the "crackle".
I tuned on 30 the first this time on SSB but tuned FT1, L28,L29 on 19 cause no AM up top.
After that for L4, I tuned the yellow side on 27.605 and the black on 26.965.
Even across the band.
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very cool.
It looks like C63 has to do with the AGC circuit, which would explain why it was causing the speaker crackle on big peaks.
the gain was not adjusting at the right time, and wasn't able to decrease in time for the big modulation peak to come through.
you made me want one of these to play with.
LC
It looks like C63 has to do with the AGC circuit, which would explain why it was causing the speaker crackle on big peaks.
the gain was not adjusting at the right time, and wasn't able to decrease in time for the big modulation peak to come through.
you made me want one of these to play with.
LC
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Yes I think so too.
There is something fishy maybe still.
SSB receive is so quiet now I'm thinking there was a 1uf there.
I still get the crackle on local stations and super heavy weights in skipland and turning the rf gain down helps but I think I still have an issue in the agc area.
lol the nail polish is pulling the needle below zero.
really dont feel like balancing that right now.
There is something fishy maybe still.
SSB receive is so quiet now I'm thinking there was a 1uf there.
I still get the crackle on local stations and super heavy weights in skipland and turning the rf gain down helps but I think I still have an issue in the agc area.
lol the nail polish is pulling the needle below zero.
really dont feel like balancing that right now.
Ok after further testing at 357 labs....It may be advisable to do the opposite on the tuning.
It's still under investigation.
Either way, something tells me there's more to these double cans than tuning both on the same frequency.
Thats why they used to put stickers on them.
It's still under investigation.
Either way, something tells me there's more to these double cans than tuning both on the same frequency.
Thats why they used to put stickers on them.
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OK after all said and done, I tuned it like in the last picture and used a 1uf for C63.
Sounds great even on the overmod locals.
Sounds great even on the overmod locals.
Reviving this thread since it is fairly on topic...
Hoping there is someone out there that can assist. I have a TRC-457 that is having what i believe to be an AGC issue. I see in this thread a fix was developed with C63. However, the CC 40D is a very different radio.
When i receive very strong SSB stations, where the AGC kicks in, I get a very loud pop from the speaker on the initial signal. The remaining peaks seem to be managed by the AGC OK, unless the signal is extremely strong (+35 db). For those +35 db the popping is on every peak.
The radio was recapped and realigned per the service manual. However, the AGC issue persists post those activities.
Turning down the RF gain does not help.
I have replaced TR10 (AGC), TR11(AGC) and TR21(AF AMP) with no improvement.
Any suggestions for improving the ACG/Eliminating the popping would be greatly appreciated.
Hoping there is someone out there that can assist. I have a TRC-457 that is having what i believe to be an AGC issue. I see in this thread a fix was developed with C63. However, the CC 40D is a very different radio.
When i receive very strong SSB stations, where the AGC kicks in, I get a very loud pop from the speaker on the initial signal. The remaining peaks seem to be managed by the AGC OK, unless the signal is extremely strong (+35 db). For those +35 db the popping is on every peak.
The radio was recapped and realigned per the service manual. However, the AGC issue persists post those activities.
Turning down the RF gain does not help.
I have replaced TR10 (AGC), TR11(AGC) and TR21(AF AMP) with no improvement.
Any suggestions for improving the ACG/Eliminating the popping would be greatly appreciated.
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Also, may be related...
NB circuit does not appear to be working. NB on/off switch verified to be operational and does bring the circuit online.
The Signal strength meter will not go below 1 s-unit on SSB mode (AM is S0) when the radio is connected to a dummy load.
I have not attempted to tune L2 "No Admit" inductors. L1 was tuned using a 23.5MHZ input tone of 1KC until a maximum reading was observed from the speaker output.
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