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Post by oldgeezer on Apr 19, 2024 14:25:02 GMT -5
That's a shame, but not unexpected these days... Local CB net shutdown. I am back to chasing skip and bought a 1000 watt output D&A Phantom.
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Post by cbrown on Apr 17, 2024 11:57:05 GMT -5
That's a shame, but not unexpected these days...
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Post by oldgeezer on Apr 14, 2024 19:43:28 GMT -5
Local CB group broke up, back chasing skip on 11 meters.
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Post by cadillaccharlie on Apr 13, 2024 12:44:45 GMT -5
Thanks for the info! I did a double diode test on both the driver & final. The driver checks okay Conductivity one way no conductivity the other way on both diodes. The final checks fried. Conductivity both ways on each diode.
Dave
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Post by 2600 on Apr 13, 2024 0:06:09 GMT -5
Pretty sure this one has the metal-can "TO-5" final transistor with a metal mount flange held by two screws. Those don't tolerate a high SWR very well, and may very well be blown.
Or might not.
Sounds like you have more going into the final transistor than you have coming out of it. A transistor tester would tell you if the final is blown. You only need to unsolder two of the transistor's three leads to clip onto a transistor and test it.
Making sure that DC power is reaching the final transistor's collector (outer case) is the one other thing that would cause what you're seeing.
A modern metal-tab plastic final transistor can be adapter to fit this radio, but it's a bit of a kluge, and you'll need an insulating shoulder washer for the mount screw and a mica washer between the metal face of the transistor's tab and the heat sink.
73
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Post by 2600 on Apr 12, 2024 23:58:37 GMT -5
The display is made by SanJian. Their model number is PLJ-6LED. It's sold in four colors that I know of, red, blue, green and yellow.
Yeah, you'll have to set it for an offset of 10.695 MHz if you buy one new. Seems to me there's a YT video showing how. The VFO's output frequency is mixed with two other crystals in the transmitter. If each of those has drifted off frequency by a half kHz, the display would be wrong by 1 kHz. If you have an external counter showing the AM carrier frequency you can tweak the offset stored in the counter to compensate and get an accurate frequency display that way. A quartz crystal is literally a moving part, and the two 5 Mhz AM-mode crystals will exhibit some frequency drift after 10,000 hours or so. Those two crystals are running all the time, not just while you're keyed up. Every transmitter is different on this count.
Hardware hookup is plug and play.
73
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Post by cadillaccharlie on Apr 12, 2024 21:42:34 GMT -5
Thanks so much for your help!! I checked all the Sams voltage points and they check okay! I have a small RF sniffer and I can get a RF reading on the input to the driver and also on the final by touching the input leads on each transistor when I key & whistle into the mic. I get a RF output on the driver but very very little RF output on the Final. I'm thinking my culprit is the final. What are your thoughts?
Dave
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Post by hellcat on Apr 10, 2024 21:16:01 GMT -5
I have a Digital Siltronix 90 by Nomad radio for a Browning Mark 3. I’d like to change the color of the display. If I got a new frequency display is it simply plug and play? or would the new one have to be reprogrammed to match the Browning? If so does anybody have the steps on how to do this?
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Post by 2600 on Apr 6, 2024 22:59:14 GMT -5
Possibly. Seems to me they used a metal-can TO-5 style final transistor with a metal "saddle" bolted to the heat sink. They were kinda fragile if the SWR got too high. That, and the radio has no provision to adjust the sideband bias current. If it runs too high, the final overheats. An oscilloscope is your best friend pinning down what to blame when this happens. 73
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Post by cadillaccharlie on Apr 6, 2024 18:56:49 GMT -5
Thanks much for your troubleshooting advice! I do have good audio but no rf whatsoever testing it as you suggested. Appears it is definitely a rf issue. Possibly blown final?
73s!
Dave
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Post by oldgeezer on Apr 5, 2024 2:26:05 GMT -5
I bought a mint condition used Uniden PC68XL 40 Channel CB Radio at $27 for backup to my main CB being a Realistic TRC-483. The Uniden is a fine CB and receives as well as the TRC-483. I turned up pot VR5 on the Uniden and now get 16 watts peak output that is 100% modulation. On transmit the Uniden is not quite as clear or loud as the TRC-483 and the Uniden has mic gain control- go figure. The TRC-483 does not need an amplified microphone either- it is that loud on transmit. The TRC-483 has a resistor cut for 16 watts peak output. I just bought a new in box TRC-483 for $35 and this will be my backup CB. The Uniden is going on the auction block, however it is a good radio. The TRC-483 is the best CB I ever used and I owned about 30 CB radios.
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Post by 2600 on Apr 4, 2024 23:55:57 GMT -5
A SSB-only radio presents a dilemma if it won't transmit. Is the fault in a RF circuit? Or is mike audio? Either one will kill the transmit power.
If you have another radio handy, tune it to the same channel as the SBE, put a foot long wire into the receiving radio's antenna socket and key the SBE. If it's an audio problem, you will hear a little bit of carrier, and probably some noise when it's keyed, and nothing else. This would suggest audio trouble. On the other hand, if you can hear a weak transmit signal and mike audio, this suggests that the tracks are being blocked in a RF circuit.
That line of radios was prone to receive and transmit audio trouble caused by 1uf and 10uf electrolytic capacitors. A 'scope would reveal how far the mike audio is getting, following it from the mike jack to the sideband modulator circuit. And if that's what you find, you should consider replacing all the electrolytic capacitors. They were not engineered to last this long to begin with.
73
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Post by Trapper_267 on Apr 3, 2024 20:06:36 GMT -5
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Post by brownbomber72 on Apr 3, 2024 17:49:25 GMT -5
If some one could show me where all those adjustments are at I would greatly apreciate it
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Post by cadillaccharlie on Apr 3, 2024 14:11:15 GMT -5
Hi all! I recently got a hold of a SBE Sidebander III which is in really nice condition. I also have a Pal VCO A-4 that I will use with this radio. The radio receives very well on all channels and works well with the VCO on receive. This is a sideband only radio so it cannot be tested with a dead key for output. The radio does not transmit. I tried 3 different SBE mics with same results, no output at all on watt meter. I am waiting+ for a Sams Photofacts book to come in but I do have the owner's manual and schematic for it. I am testing it with a 13.8 VDC 10 AMP power supply which has an analog voltage & amp meter on it. When I key the mic without even speaking into it the amp meter kicks to around 1 1/2 amps. Where would be the best section to start looking? Could the final be shorted or a related Cap? Any help will be appreciated! I'm more an old school tube rig guy but I do like some solid-state crystal rigs. Thanks for looking! Dave
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Post by Trapper_267 on Apr 1, 2024 11:35:43 GMT -5
Here's what i ran into as far as the carrier on SSB with the mic gain at zero. And Thank you Nomad for your encurging word's on the Neutralization and the by gosh, By golly method to adjust it. I did manage to get USB to stop sending a carrier, But no luck on LSB. I could get LSB down to about 1/2 watt, But hardley any AM carrier, I had gotten a BM board from Fixr and installed his BM board and the LSB carrier disapeared, Both BM board's had all the electrolithic cap's replaced and i never looked in to what was causing the BM board to have LSB carrier
I also installed Nomad's AA board noise kit and it is also fixed ((( Thank's Mr. Nomad))
Good luck Brownbomber72
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Post by brownbomber72 on Apr 1, 2024 5:59:55 GMT -5
Thanks for the info. Where would I find C706?
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Post by 2600 on Mar 31, 2024 22:33:45 GMT -5
Alignment is the starting point for performance issues. The carrier you see on SSB transmit is likely not anywhere near the selected channel frequency. Good chance that it's from the final stage oscillating. An inline frequency counter that shows what's coming out of the transmitter will most likely reveal that your SSB carrier is not anywhere near the selected channel frequency.
Typically this is caused by someone tweaking C706 for the highest wattmeter reading. C706 is not a "peaking" adjustment. It serves to cancel out the final tube's tendency to leak some of its output energy back into the final tube's input circuit. This will make it oscillate, not so different from the feedback "howl" you get by pointing a stage mike at the PA speakers. Only it's RF energy, not audio.
Unfortunately, the one part of the factory's alignment procedure that stinks is the one for setting C706. I'll guess that the adjustment screw in C706 is quite loose. Simply tightening it until you feel some real friction might stop the SSB carrier.
Just one problem. Any time you turn C706 it will change the peak setting of C711, the Plate Tune control, and the slug position of T700, the driver tube's output coil. Each of those will have to be peaked again, any time the setting of C706 is altered.
As for the hum, I have seen too many D201 radios that were "recapped" with only a fraction of the long list of electrolytic caps, usually the big ones replaced. The short 4-section 'can' C624 will cause hum issues if it's original. Likewise, there are a handful of other 8 or 10 uf 450-Volt caps that cause trouble if they are original. There are three electrolytic caps on the plug-in "BA" circuit board next to the 6L6GC audio power tube V603. If they are original, that could cause hum trouble.
The D201 has enough routine faults to qualify as a "barrel of monkeys" radio. Until you proceed to align it, when the phrase "herding cats" may come to mind.
Oh, and the one-channel wrong issue could be as simple as the set screw on the crystal channel dial.
73
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Post by brownbomber72 on Mar 31, 2024 17:57:00 GMT -5
Picked up one recently that already has all caps and resistors replaced. All tubes test good. Here are the issues:
AM transmit: I can only get a 1 watt carrier at keyup with a swing to 10-15 watts. If I turn the transmitter tone control past halfway the key will jump up to 5 watts with no forward swing and a squealing sound will start coming from somewhere inside the radio.
SSB transmit: At keyup it shows almost a 15 watt carrier
Receive: It is off by one channel. Have to put it on channel 22 to be on 21 etc.
And for a recapped radio there is quite alot of hum coming from the speaker. What could be causing all these issues?
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Post by oldgeezer on Mar 27, 2024 21:35:07 GMT -5
I wrote an article about 2 years ago 'Best Deal on a Cheap CB AM Radio'. These were Radio Shack CBs. Two years later I see very few if any for sale unlike a lot for sale two years ago.
Now in 2024, what is a cheap CB radio. I say $35. Old vintage CBs are not reliable due to failing capacitors, thus year 2000 or newer CBs are good and I believe the PC68XL came out in 2005. I say the best deal is a Uniden PC68XL. A lot are for sale on eBay for $35 so buy a working CB as stated in the eBay description vs a parts radio that is not tested. Although newer the PC-68LTX is available, modulation mod is more involved with a jumper and capacitor added vs one pot VR-5 adjust on the PC-68XL. For some reason the PC78LTW cost about twice as much ($75) and has no benefit vs the PC68XL IMO. The PC68XL has RF gain and microphone gain. I would not buy any CB without an RF gain. Adjust VR-5 potentiometer on circuit board for higher modulation. I considered the Cobra 29 LTD Classic, but these radios are about $70 used. I read CBers think the Uniden PC68XL is the best mobile CB they ever owned.
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Post by bountyhunter on Mar 27, 2024 12:15:02 GMT -5
Thank you! I'll get one ordered.
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Post by 2600 on Mar 26, 2024 23:50:28 GMT -5
The 0B2 is a shunt regulator. It holds the voltage more or less steady by drawing either more or less current needed to hold the voltage across the tube steady at (I think) around 105 Volts DC. Later models used a 10-Watt zener diode. If your 0B2 shows 265 Volts, it has failed and needs to be replaced. We use a 100-Volt 10-Watt zener in place of that tube. The later Browning receivers used this part: stores.goldeneagleradios.com/1n3005b-zener-diode-100-volts-10-watts/It's at least as rugged as the 0B2 tube, and tends to last longer. Until that 31.4 crystal is running, you won't hear a thing. V3 has to be good for it to run. If the crystal proves to be bad, Barkett has that, too: stores.goldeneagleradios.com/browning-receiver-crystal-31-400/73
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Post by Trapper_267 on Mar 26, 2024 17:55:10 GMT -5
Thank's for the quick call today Mr. Nomad.
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Mar 26, 2024 16:47:28 GMT -5
Thanks 2600. I had forgotten the double sided circuit bds from the 80's. Not a good time to be working in a TV shop. Repeated call backs, ANGRY, RUDE customers missing their TV time. I came up with a fix for those nasty little bubbling eyelets. Heat the eyelet until it starts bubbling and stick a small copper wire thru it until it comes out the other side. Add a little flux and it actually shines, no more bubbles. Never had another call back, for that problem. That's how I dealt with plated through holes as well.It seemed to work well.
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Post by bountyhunter on Mar 26, 2024 13:48:45 GMT -5
I just started on a Browning Eagle 68R. Replaced all caps,tested all the tubes except 0B2. Receive is dead, audio is working. The 31.4 mhz oscillator is not working. Voltage on the plate of 0B2 is high at 265v. Does this mean the 0B2 leaked all the magic gas out and needs replaced. I'm not familiar with the 0B2 and I don't have a spare. I don't have much hair left to pull out. Any help is greatly appreciated. Thank you
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Post by bountyhunter on Mar 26, 2024 0:37:02 GMT -5
Thanks 2600. I had forgotten the double sided circuit bds from the 80's. Not a good time to be working in a TV shop. Repeated call backs, ANGRY, RUDE customers missing their TV time. I came up with a fix for those nasty little bubbling eyelets. Heat the eyelet until it starts bubbling and stick a small copper wire thru it until it comes out the other side. Add a little flux and it actually shines, no more bubbles. Never had another call back, for that problem.
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Post by bountyhunter on Mar 26, 2024 0:23:27 GMT -5
Never had much trouble with my Dak 10. It's 42 years old. Recapped it 20 years ago. Trams, had my fill of them. Sound great but total junk. I think they used Elmer's glue to hold the traces on the board. the channel selector is truly a POS. Best bet would be to pay too much money for 2 D201A's and get both overhauled $$$. That way you have a spare when one breaks.
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Post by 2600 on Mar 25, 2024 23:33:56 GMT -5
It looks for all the world like something out of the Thomas and Betts catalog, but I've never found it there.
73
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Post by 2600 on Mar 25, 2024 23:32:43 GMT -5
As a rule, only the front-end adjustments in a receiver will affect signal-to-noise ratio. Once the signal passes into the first mixer stage, the noise content is pretty well established, and later stages of the receiver get peaked for max signal. Never have seen the downstream adjustments have a separate effect on noise and signal.
This is where a SINAD meter shines. It can distinguish signal from noise as well or better than your ears. Peaking front-end adjustments using only the S-meter will tend to exaggerate the receiver's internal noise level, but mostly only in solid-state radios. Tube radios don't seem to exhibit that trait.
Sure don't know why.
73
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Mar 25, 2024 19:59:01 GMT -5
Just wondered how others tune SSB RX. Do you peak T501 and T502 ? I find when peaked the white noise seems excessive to the signal, and I detune for the best signal to noise ration, so I can hear a lower levcel signal with minimum noise competing with it. I do the same with AM, finding the white noise there also excessive when T300, 301, 302 peaked etc. 389 I run across that issue frequently on newer RCI style radios. The front end coil, I typically detune from peak, as the signal/Noise ratio is better. However, I can't recall having similar concerns with the D201. Most of the better tube rigs have a fairly low noise floor, and I've never had to "detune" any of the slugs.
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