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Post by oldgeezer on Jul 9, 2019 22:23:14 GMT -5
Tube CB radios have the most clear sounding receive audio. It can sort out the most difficult signals. I know some solid-state may sound as good, but about every tube type CB sounds good and most have excellent sensitive receivers. The best of the best are Tram D201 & D201A plus the Browning Golden Eagle MK4 and MK4A. Tram 23 channel are about $400 and the 40 channel D201A about $750 in working condition. The Browning Golden Eagle MK4 are about $800 & the MK4A well over $1000 in working condition.
Fortunately other tube type 23 & 40 channel radios have about the same performing reception and cost $30 to $200 in good condition. 23 channel are $30 to $125 and the 40 channel versions can cost about $200 with a few around $100 to $120. The Kris 23+, Gemtronics GTX-2300 & GTX-5000, Teaberry model T, Lafayette Comstat 25, Colt Midnight Special and Robyn T-123 & T-240D are all the same tube chassis made in Japan.
The Courier 23 Plus, Knight Safari and Knight KN-2565B are US made chassis. Both are dual conversion and use a quiet front end (RF amp and/or mixer tube) using the very quiet Nuvistor tube. Another radio is the Sonar FS-23 & FS-40 (40 channel) and Regency Range Gain radios. The Sonar are sold at a premium with the 23 channel around $200 and the 40 channel around $450. These radios are very worth well to own and perform slightly better than the Japanese Chassis. The Cobra Cam 88 is slightly less of the Japanese receiver, but still good.
Most of these radios have modest modulation with dead key at four watts and modulate to 8 to 10 watts. The actual peak may be a little higher. The best modulation radios have a switch called Range Gain, Range Expander, etc and these radios achieve at least the 10 watt range. The Regency Range Gain radios were built to have more than 10 watts modulation as the FCC rules did not specify peak modulation. These radios usually dead keys at 3 watts and modulate to 15 watts. Does it really matter if a radio deads keys 2 watts and modulates to 22 watts? Running an amplifer makes up for any amount of modulation, but we do not use amps, right?
The tube type 40 channel tube radios cost a premium, but I hardly ever hear any skip above channel 23 anyways. Plus 23 channel are crystal radios and have no 40 channel synthesizer noise on the receiver. Although it is very low anyways. I will not pay the premium for a 40 channel tube radio. However, a crystal may go bad. Kens Electronics in MI has replacement crystals.
The tube radios need electrolytic and paper capacitor replacement. The newer Japanese chassis may run for a while longer with original capacitor. So, if you lack the skills to replace the capacitors, buy the Japanese chassis radios.
My CB radios are a Courier 23 Plus in the blue painted front panel and the Knight KN-2565B. I am also a ham radio operator, but I also like CB radio a lot. I highly recommend the 23 or 40 channel tube type radios.
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Post by 321 treeclimber on Jul 10, 2019 4:59:14 GMT -5
Hello geezer, well put,thank you. I have a few old tube rigs and found them to be a lot of fun. I also found them to be a lot of work...but worth it. The comstat 25a has been a work horse. After recapping and tube swapping she hums along paired with a raider nicely. I've stumbled on an elenco compressor amp but cant find any instruction on installation or operation, nor have i found a schematic. Hummerlund made a great little six chnnl. I own a working one now. Thanks for the insight. There are guys on this forum who have consistently helped me to learn about and enjoy cb radio more than ever. 321
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Post by oldgeezer on Jul 10, 2019 5:59:29 GMT -5
Yes, there are many more tube type CB radios that have the 5 thru 12 channel transmit with a variable frequency receiver. Due to cost of crystals and limited transmit coverage I kept my article to 23 or 40 channel tube radios.
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Post by 321 treeclimber on Jul 10, 2019 6:50:38 GMT -5
Yep'r, have relyed on kens for many a crystal!
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Post by oldgeezer on Jul 11, 2019 9:38:09 GMT -5
BTW- why is the Courier 23+, Ranger and Royale tube CBs great at reception? The front-end tubes used makes for superior receive. It uses a 6BS8 VHF TV tube. It is used in cascade for 10000 trans-conductance. 10000gm is very high. VHF is much higher in frequency than CB, thus performance is even better on CB frequencies vs TV use and is very quiet like a MOS-FET transistor used in modern solid-state radios. Next, the Courier uses a Nuvistor mixer tube called a 6CW4. This tube used as a mixer is very high gain and low noise. It does not get better. Other tube type CBs may Nuvistors and VHF RF tubes and others not. Only way to know is to look up the CB schematic at CB Tricks on the internet.
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Post by 321 treeclimber on Jul 11, 2019 21:40:12 GMT -5
Well I've completed the first part of the refurbishing work on the skipper300. The new relays are in and so is a burned resistor.shopping for tubes now. Hopefully i can get this amp working.ive cleaned it thoroughly and have gone over every thing. Why would it work intermittently. Heat i figure, something gets hot under key-up and shuts off.
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Post by 321 treeclimber on Jul 12, 2019 6:48:01 GMT -5
This morning i replaced the two barrel,450v caps and 4 diodes and then tested. Again i tune it and it works first couple of key downs then becomes erratic, even dropping out completely. Trying to retune it only puts it all over the place. Back to the drawing board.
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Post by aardvark on Jul 13, 2019 16:45:53 GMT -5
Treeclimber sounds like you have a bad solder joint or connection somewhere and it kind of sounds like its in the tank circuit. Look at your adjustable tune and load caps connections and the coil make sure all those connects look good. Be careful and unplug and let the caps drain down and short the coil to ground before touching it otherwise it will give you a hard shock may even kill you. all kinds of HV there!!
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Post by 321 treeclimber on Jul 13, 2019 21:25:11 GMT -5
10-4 aardvark. I will look at that tomorrow. I also found that when i key often like as i am tuning then testing, it gets really warm then the symptoms start. But if i wait 5 minutes or so, it stabilizes til it gets hot again. It has a continues run fan built in so it cools off quick. I also noticed one of the tubes silver top cap seems loose
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Post by aardvark on Jul 14, 2019 13:55:05 GMT -5
treeclimber cold or bad solder joints will act like that work while cold and open as it gets hot. Also make sure your tuning caps have good grounds and are not loose.
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Post by 321 treeclimber on Jul 14, 2019 15:41:47 GMT -5
10-4 i will continue to look
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