|
|
Post by Night Ranger on Jul 25, 2015 11:11:06 GMT -5
I pulled out my 1976 Realistic TRC-30a last night to talk to the locals on our own CRR on channel 12. All was ok until the skip started coming out of Florida this morning. The selectivity on that radio is not very good. It looks like a 11.275 MHz crystal in the 1st IF chain would help. I don't see a 455 kHz ceramic filter in the 2nd IF, but there is one 455 kHz coil that looks a little fatter than normal. The schematic shows what looks like a combination of a 455 kHz coil and possibly some type of filter in the same can. It don't see any coupling capacitors between the 455 kHz coils, but a 455 kHz crystal or ceramic filter could be inserted in place of the emitter bypass capacitor in IF amp Q303. As there appears to be an IF amp gain adjust in the same location the gain could be upped to compensate for the 455 kHz filter insertion loss. www.cbtricks.com/radios/realistic/trc_30/graphics/realistic_trc_30a_sm_pg10_11_sch.jpgIn any case, if I'm going to use that radio for any regular listening the selectivity will definitely have to be increased to be tolerable. Night Ranger |
|
|
|
Post by BBB on Jul 26, 2015 8:28:15 GMT -5
Yep, pretty basic radio. I tried one "on air" and the fidelity was thin sounding. Got the box and all. It does have a nice clean look though.
|
|
|
|
Post by cbrown on Jul 27, 2015 8:27:58 GMT -5
A very popular radio in this area, I know at least a few dozen that were on the air.
|
|
|
|
Post by Night Ranger on Jul 27, 2015 11:46:07 GMT -5
I pulled out my 1976 Realistic TRC-30a last night to talk to the locals on our own CRR on channel 12. All was ok until the skip started coming out of Florida this morning. The selectivity on that radio is not very good. It looks like a 11.275 MHz crystal in the 1st IF chain would help. I don't see a 455 kHz ceramic filter in the 2nd IF, but there is one 455 kHz coil that looks a little fatter than normal. The schematic shows what looks like a combination of a 455 kHz coil and possibly some type of filter in the same can. It don't see any coupling capacitors between the 455 kHz coils, but a 455 kHz crystal or ceramic filter could be inserted in place of the emitter bypass capacitor in IF amp Q303. As there appears to be an IF amp gain adjust in the same location the gain could be upped to compensate for the 455 kHz filter insertion loss. www.cbtricks.com/radios/realistic/trc_30/graphics/realistic_trc_30a_sm_pg10_11_sch.jpgIn any case, if I'm going to use that radio for any regular listening the selectivity will definitely have to be increased to be tolerable. Night Ranger Apparently part of the bleedover was due to a dirty transmitter on channel 6 from someone in Florida. Even after switching to a more selective receiver I could still hear that bonehead in Florida splattering from channel 6 all the way up to channel 14 and possibly beyond. Night Ranger |
|
|
|
Post by doctor on Jul 27, 2015 13:11:36 GMT -5
NOW , now our brothers on chnl 6 are authorized to run 1 to 2 kw and splatter, the FCC never touches them..JUST JOKING> they do the same here splatter 6 to 11 usually, but 11 is becoming the same way.
DOCTOR/795
|
|
Sandbagger
Administrator/The Boss 
Posts: 6,250 
|
Post by Sandbagger on Jul 28, 2015 20:34:03 GMT -5
NOW , now our brothers on chnl 6 are authorized to run 1 to 2 kw and splatter, the FCC never touches them..JUST JOKING> they do the same here splatter 6 to 11 usually, but 11 is becoming the same way. DOCTOR/795 The thing with splatter is that it's a dirty signal, spilling up and down many channels from their operating channel. And no radio receiver can reject spurious signals that actually falls on-channel. |
|
Sandbagger
Administrator/The Boss
Posts: 6,250
|
Post by Sandbagger on Jul 28, 2015 20:45:11 GMT -5
I pulled out my 1976 Realistic TRC-30a last night to talk to the locals on our own CRR on channel 12. All was ok until the skip started coming out of Florida this morning. The selectivity on that radio is not very good. It looks like a 11.275 MHz crystal in the 1st IF chain would help. I don't see a 455 kHz ceramic filter in the 2nd IF, but there is one 455 kHz coil that looks a little fatter than normal. The schematic shows what looks like a combination of a 455 kHz coil and possibly some type of filter in the same can. It don't see any coupling capacitors between the 455 kHz coils, but a 455 kHz crystal or ceramic filter could be inserted in place of the emitter bypass capacitor in IF amp Q303. As there appears to be an IF amp gain adjust in the same location the gain could be upped to compensate for the 455 kHz filter insertion loss. www.cbtricks.com/radios/realistic/trc_30/graphics/realistic_trc_30a_sm_pg10_11_sch.jpgIn any case, if I'm going to use that radio for any regular listening the selectivity will definitely have to be increased to be tolerable. Night Ranger Don't be too hard on that TRC-30a. It's not a bad radio for what it is. My biggest complaint about that radio was the unregulated power supply. It would almost always backswing along with the lights dimming. Many people who ran them back in the day, did so with external regulated supplies, to get better performance, and a little more peak power out. Radio Shack sold a ton of those radios in the mid 70's. A lot of newbies got their start with one of those. The receiver suffered from RF overload (desense), from really strong local signals, but was otherwise about average compared to other contemporary radios of the time. |
|
Sandbagger
Administrator/The Boss
Posts: 6,250
|
Post by Sandbagger on Jul 28, 2015 20:47:40 GMT -5
Yep, pretty basic radio. I tried one "on air" and the fidelity was thin sounding. Got the box and all. It does have a nice clean look though. The TRC-30 actually sounded pretty good on a D-104. It's predecessor, the TRC-23C on the other hand, was very tinny sounding. |
|
|
|
Post by Night Ranger on Jul 29, 2015 13:36:10 GMT -5
I pulled out my 1976 Realistic TRC-30a last night to talk to the locals on our own CRR on channel 12. All was ok until the skip started coming out of Florida this morning. The selectivity on that radio is not very good. It looks like a 11.275 MHz crystal in the 1st IF chain would help. I don't see a 455 kHz ceramic filter in the 2nd IF, but there is one 455 kHz coil that looks a little fatter than normal. The schematic shows what looks like a combination of a 455 kHz coil and possibly some type of filter in the same can. It don't see any coupling capacitors between the 455 kHz coils, but a 455 kHz crystal or ceramic filter could be inserted in place of the emitter bypass capacitor in IF amp Q303. As there appears to be an IF amp gain adjust in the same location the gain could be upped to compensate for the 455 kHz filter insertion loss. www.cbtricks.com/radios/realistic/trc_30/graphics/realistic_trc_30a_sm_pg10_11_sch.jpgIn any case, if I'm going to use that radio for any regular listening the selectivity will definitely have to be increased to be tolerable. Night Ranger Don't be too hard on that TRC-30a. It's not a bad radio for what it is. My biggest complaint about that radio was the unregulated power supply. It would almost always backswing along with the lights dimming. Many people who ran them back in the day, did so with external regulated supplies, to get better performance, and a little more peak power out. Radio Shack sold a ton of those radios in the mid 70's. A lot of newbies got their start with one of those. The receiver suffered from RF overload (desense), from really strong local signals, but was otherwise about average compared to other contemporary radios of the time. I like the tone of the receiver, and it is fairly quiet. The transmit audio is stock and sounds pleasant with the Radio Shack amplified desk mic from the same period. I found a Chinese seller on Ebay selling LT455EW 455 kHz ceramic filters cheap, so I ordered about 20 of them. I think I'll put one or more of them in the TRC-30a. I may have an 11.275 MHz crystal lying around from a junked radio as well. I like the radio, but the selectivity has to come up. My Mom's Morse CB-2000 CB radio drove me nuts with bleedover back in 1977 while my Midland 13-853 was in the shop. Night Ranger |
|
|
|
Post by ab5ni on Nov 30, 2015 3:41:56 GMT -5
Don't be too hard on that TRC-30a. It's not a bad radio for what it is. My biggest complaint about that radio was the unregulated power supply. It would almost always backswing along with the lights dimming. Many people who ran them back in the day, did so with external regulated supplies, to get better performance, and a little more peak power out. Radio Shack sold a ton of those radios in the mid 70's. A lot of newbies got their start with one of those. The receiver suffered from RF overload (desense), from really strong local signals, but was otherwise about average compared to other contemporary radios of the time. I like the tone of the receiver, and it is fairly quiet. The transmit audio is stock and sounds pleasant with the Radio Shack amplified desk mic from the same period. I found a Chinese seller on Ebay selling LT455EW 455 kHz ceramic filters cheap, so I ordered about 20 of them. I think I'll put one or more of them in the TRC-30a. I may have an 11.275 MHz crystal lying around from a junked radio as well. I like the radio, but the selectivity has to come up. My Mom's Morse CB-2000 CB radio drove me nuts with bleedover back in 1977 while my Midland 13-853 was in the shop. Night Ranger First CB rig I ever owned. I still have a fondness for the rig. My Dad and I made an inverted-V antenna for the thing. His handle was "Chicken Picker" -- how he came up with that one, I'll never know  -- and a lot of folks would ask him what kind of antenna he was using. When he explained it was made out of coaxial cable and wire, they told him he was nuts, didn't know what he was doing, and that he was going to burn up a perfectly good CB radio .Years later, I stripped the thing for parts, and I wish I'd never have done that. When I can afford it, I guess I'll be in the market for one. Hope I can find a decent one on e-bay. 73, Randy |
|
