Realistic TRC-40 Navaho Pro 23 Ch

[midnight]

Hi All,

Anyone got the tuneup info on this circa 1973-or-so base radio? Nothing posted on CB Tricks, but it's in SAMS #42 per their site. I have a pretty decent cosmetic example with the stock mic and a mechanical-digital clock that still works (with alarm clock function that still works). Got the cigarette smoke off it and it's not too bad-looking.

It does 2 watts on a meter that's calibrated to a Model 43 Bird (stingy) and I don't have a modulation meter but it is a mud duck of the first order; it appears to be stock and un-messed with.

Thanks!

[Sandbagger]

Oct 3, 2010 0:22:49 GMT -5 midnight said:

Hi All,

Anyone got the tuneup info on this circa 1973-or-so base radio? Nothing posted on CB Tricks, but it's in SAMS #42 per their site. I have a pretty decent cosmetic example with the stock mic and a mechanical-digital clock that still works (with alarm clock function that still works). Got the cigarette smoke off it and it's not too bad-looking.

It does 2 watts on a meter that's calibrated to a Model 43 Bird (stingy) and I don't have a modulation meter but it is a mud duck of the first order; it appears to be stock and un-messed with.

Thanks!

Wanna sell it? The TRC-40 was probably the very first 5watt CB I ever talked on back in 1973.

I just missed one on Ebay and it went for just over $15....... Rats!


The thing you have to remember with radios that are approaching 40 years old is that certain parts (like electrolytic caps and crystals) will age and eventually fail. So performance will decrease as this process continues. It's probably not something a simple alignment will cure, especially if it looks like it's never been messed with. Also, remember that radios were rated for input power back then and a 5 watt input rated radio put out closer to 3 watts, so anywhere close to 3 watts out is not far off.

[midnight]

Oh, I hear you on the electrolytics and crystals --story of my life over here, Sandbagger. The newest radio I own is a Cobra 142 but most of my radios are AM-only Brownings, a Tram Titan II, miscellaneous 1970s-era mobiles and so on. Toss in a couple of Matsush- ita-chassis radios (Lafayette and GemTronics) and that about covers it.

For the moment, I think I'll hang onto it but that could easily change. It's not like I NEED it, with all of the antiques that need a technician's touch over here (a real technician, not me, LOL). Just wanted to try it out a bit and see how it goes. Thought the mod could use a little help; the 2-watt output being calibrated to the Bird is right in line with my Cobra, and other radios that are in good working order.

Just wondered if anyone could I.D. the mod pot and mention if the mod limiter diode is particularly restrictive. What do you think Sandbagger?

[Sandbagger]

Oct 3, 2010 22:00:54 GMT -5 midnight said:

Oh, I hear you on the electrolytics and crystals --story of my life over here, Sandbagger. The newest radio I own is a Cobra 142 but most of my radios are AM-only Brownings, a Tram Titan II, miscellaneous 1970s-era mobiles and so on. Toss in a couple of Matsush- ita-chassis radios (Lafayette and GemTronics) and that about covers it.

For the moment, I think I'll hang onto it but that could easily change. It's not like I NEED it, with all of the antiques that need a technician's touch over here (a real technician, not me, LOL). Just wanted to try it out a bit and see how it goes. Thought the mod could use a little help; the 2-watt output being calibrated to the Bird is right in line with my Cobra, and other radios that are in good working order.

Just wondered if anyone could I.D. the mod pot and mention if the mod limiter diode is particularly restrictive. What do you think Sandbagger?

Ok, so you're a fellow collector of vintage radios, so you know what to expect. I'm in the same place, with a fair collection of my own. Most of which need some sort of TLC at the minimum to keep them going.

I'll have to check my information to see if I have any data on the Navaho Pro. Most radio of that vintage had either no modulation limiting, or simple diode clippers. If you have a very low modulation situation, most likely you have a nearly open electrolytic coupling cap somewhere in the audio chain, or maybe a bad mic element.

[wd8nia]

Oct 4, 2010 6:26:19 GMT -5 Sandbagger said:

Oct 3, 2010 22:00:54 GMT -5 midnight said:

Oh, I hear you on the electrolytics and crystals --story of my life over here, Sandbagger. The newest radio I own is a Cobra 142 but most of my radios are AM-only Brownings, a Tram Titan II, miscellaneous 1970s-era mobiles and so on. Toss in a couple of Matsush- ita-chassis radios (Lafayette and GemTronics) and that about covers it.

For the moment, I think I'll hang onto it but that could easily change. It's not like I NEED it, with all of the antiques that need a technician's touch over here (a real technician, not me, LOL). Just wanted to try it out a bit and see how it goes. Thought the mod could use a little help; the 2-watt output being calibrated to the Bird is right in line with my Cobra, and other radios that are in good working order.

Just wondered if anyone could I.D. the mod pot and mention if the mod limiter diode is particularly restrictive. What do you think Sandbagger?

Ok, so you're a fellow collector of vintage radios, so you know what to expect. I'm in the same place, with a fair collection of my own. Most of which need some sort of TLC at the minimum to keep them going.

I'll have to check my information to see if I have any data on the Navaho Pro. Most radio of that vintage had either no modulation limiting, or simple diode clippers. If you have a very low modulation situation, most likely you have a nearly open electrolytic coupling cap somewhere in the audio chain, or maybe a bad mic element.

Bad xtals....bah, humbug. I have some oldies and want to pick up a select few more back in the day rigs; but, I promised myself I won't buy anything else until the Johnson 223 is up and running again. To date, I've picked up 5 of them, each with one problem or another and bad extals has been predominant among them.

Finally scored one with good selector pack, took all the good parts from the 5, which left me with a B and an H model, and they're boxed waiting for Alan's attention. It's a be careful what you wish for situation....



Strangely, the B model has the good xtal pack and the H model (last in the line) had one bad xtal.

[Sandbagger]

Oct 4, 2010 6:26:19 GMT -5 Sandbagger said:

Oct 3, 2010 22:00:54 GMT -5 midnight said:

Oh, I hear you on the electrolytics and crystals --story of my life over here, Sandbagger. The newest radio I own is a Cobra 142 but most of my radios are AM-only Brownings, a Tram Titan II, miscellaneous 1970s-era mobiles and so on. Toss in a couple of Matsush- ita-chassis radios (Lafayette and GemTronics) and that about covers it.

For the moment, I think I'll hang onto it but that could easily change. It's not like I NEED it, with all of the antiques that need a technician's touch over here (a real technician, not me, LOL). Just wanted to try it out a bit and see how it goes. Thought the mod could use a little help; the 2-watt output being calibrated to the Bird is right in line with my Cobra, and other radios that are in good working order.

Just wondered if anyone could I.D. the mod pot and mention if the mod limiter diode is particularly restrictive. What do you think Sandbagger?

Ok, so you're a fellow collector of vintage radios, so you know what to expect. I'm in the same place, with a fair collection of my own. Most of which need some sort of TLC at the minimum to keep them going.

I'll have to check my information to see if I have any data on the Navaho Pro. Most radio of that vintage had either no modulation limiting, or simple diode clippers. If you have a very low modulation situation, most likely you have a nearly open electrolytic coupling cap somewhere in the audio chain, or maybe a bad mic element.

Well, I found some information on the TRC-40. There is no adjustable mod gain or limiter. The limiter feedback rectifier diodes are D8 & D9.

That's an interesting design. A heavy dose of early IC's used for the noise blanker, the squelch and the audio preamp. The IF has nice filters and multiple tuned stages so it should be fairly selective. A FET front end is also somewhat unusual. The biggest negative is that the built-in power supply has no regulation.

[midnight]

Thanks so much for digging up that info, Sandbagger. You mentioned that limiter feedback rectifier diodes are D8 & D9, and I wondered if you can comment for the layman on their principles of operation in the absence of any modulation gain function or limiter.

Based on your research input, this radio sounds like they turned their designer loose on a then-new-componentry jag with the ICs and FET front end; witness their inclusion proudly proclaimed on the radio's face. I have less than an hour on it, as a neighbor less than two miles away told me to get a real radio to talk on, lol. Your comment on the mic element is a great place to start, especially for a novice like me. The neighbor didn't complain about signal or off-frequency transmission, just very low mod, so there we go to get started, perhaps?

WD8NIA, looks like you've got a fun project going there; hope Alan can put you out front with those rigs.

Sandbagger, I'm just hoping to find that elusive modulation monster like the SBE Console II mentioned on this board elsewhere. I picked up a Hy-Gain V with a Siltronix Model 90 setup in the same box lot and it works great on AM but tried the patience of SSB acquaintances because it required constant touch-ups on SSB. That Hy-Gain radio's been tweaked and peaked and is loud but everyone hates its audio even on AM crystal operation. I put a NOS Hy-Gain power mic on there with a new battery and operators still said they hated the audio but liked the signal and said it was loud, just not in a good way. Sounds like a radio in search of a mic.

Anyhow, shall I let you know when it's time to thin the herd a bit?

Thanks again.

[midnight]

A little update:

I plugged the stock mic from my Hy-Gain V into the Navaho and got much better reports from about 10 miles away from a friend in a stationary mobile. A local tech about four miles away said it sounded fine, but "stock-ey," so I broke out the NOS Hy-Gain hand-held power mic and stabbed a new 7.5-volt battery into it (the custom-made battery I bought from Batteries Plus took a crap with less than a half-hour of key time on it, $8!) and he said it sounded all right to him but no raves. Anyway, a better mic surely helped. Hope this Duracell 7.5-er lasts longer than that other one.

[Sandbagger]

Oct 6, 2010 0:06:38 GMT -5 midnight said:

A little update:

I plugged the stock mic from my Hy-Gain V into the Navaho and got much better reports from about 10 miles away from a friend in a stationary mobile. A local tech about four miles away said it sounded fine, but "stock-ey," so I broke out the NOS Hy-Gain hand-held power mic and stabbed a new 7.5-volt battery into it (the custom-made battery I bought from Batteries Plus took a crap with less than a half-hour of key time on it, $8!) and he said it sounded all right to him but no raves. Anyway, a better mic surely helped. Hope this Duracell 7.5-er lasts longer than that other one.

I'm not surprised. Most of the older solid state 23 channel radios did not have a lot of internal microphone gain, and to really get them to sound good, pretty much meant that you had to put an amplified mic on it.

[Sandbagger]

Oct 5, 2010 22:02:47 GMT -5 midnight said:

Thanks so much for digging up that info, Sandbagger. You mentioned that limiter feedback rectifier diodes are D8 & D9, and I wondered if you can comment for the layman on their principles of operation in the absence of any modulation gain function or limiter.

Based on your research input, this radio sounds like they turned their designer loose on a then-new-componentry jag with the ICs and FET front end; witness their inclusion proudly proclaimed on the radio's face. I have less than an hour on it, as a neighbor less than two miles away told me to get a real radio to talk on, lol. Your comment on the mic element is a great place to start, especially for a novice like me. The neighbor didn't complain about signal or off-frequency transmission, just very low mod, so there we go to get started, perhaps?

WD8NIA, looks like you've got a fun project going there; hope Alan can put you out front with those rigs.

Sandbagger, I'm just hoping to find that elusive modulation monster like the SBE Console II mentioned on this board elsewhere. I picked up a Hy-Gain V with a Siltronix Model 90 setup in the same box lot and it works great on AM but tried the patience of SSB acquaintances because it required constant touch-ups on SSB. That Hy-Gain radio's been tweaked and peaked and is loud but everyone hates its audio even on AM crystal operation. I put a NOS Hy-Gain power mic on there with a new battery and operators still said they hated the audio but liked the signal and said it was loud, just not in a good way. Sounds like a radio in search of a mic.

Anyhow, shall I let you know when it's time to thin the herd a bit?

Thanks again.

Modulation limiting in those older radios was very simple. A sample of the modulation audio was rectified by diodes and that resultant D.C. voltage was fed back to the microphone amp transistor, at the emitter, which reduces it's gain proportionally to the amount of excess modulation. It wasn't as effective as the hard clamps they employ on more modern rigs (which most people tend to clip), but it was better than nothing.

Modulation is a very complex process to understand. "Loudness", or the perception of "loudness" is only one element of it. The other (and IMHO more important) is tonal quality or frequency response. Having a radio that sounds "loud" will not be pleasant to listen to if the tone quality sounds like you're holding your noise, or have a pillow stuck over the mic. Some radios are "tinny" and have almost no low end. Other radios sound muffled. The mic you choose to run on these radios can compensate for some of those traits. A D104 mic tends to boost higher frequencies and makes a good match for radios that tend to sound muffled and flat on a stock mic. Conversely, a Turner Super Sidekick, is a very bassy mic, which mates up well to those "tinny" sounding radios.

For those who like to experiment, you can often change the frequency response of your radio by changing coupling and/or bypass caps in the audio stage. Some guys get very serious and hook their rigs up to audio processors and graphic equalizers. While these really do sound good, it's usually too much for the average guy.

[cbrown]

Oct 6, 2010 0:06:38 GMT -5 midnight said:

stabbed a new 7.5-volt battery into it (the custom-made battery I bought from Batteries Plus took a crap with less than a half-hour of key time on it, $8!) Hope this Duracell 7.5-er lasts longer than that other one.

I've had good luck with the Duracell MN175, lasts a long time. If you search online you can find them cheap enough. I paid about $3 a piece for them.

[midnight]

Thanks for the explanation on the mod limiting for the older radios. I only knew about the clamping technique. I don't love the sound of clipped radios and agree with you on the key being tonality.

CB Brown, thanks for the battery tip; I will keep that in mind.

I have a Behringer V-Amp 2 electric guitar processor/amp modeler that I am convinced would be a killer way to not only boost audio gain on a radio mic but also to go the usual EQ board approach one better by introducing a zillion combinations of amplification approaches from the clean tube preamp that would make a good starting point and onward through Vox- or Marshall-style, etc. guitar amp tonality (running a voice through it, not a guitar of course) and so on. It provides a wide range of cabinet selection combos that change the tone of every amp brand/style selected and there are individual low, midrange and high frequency settings on potentiometers along with a presence control for brightness and a "drive" gain control that switches on and off.

I just can't figure out how one would run it between a mic and the radio, and how to switch the radio carrier on, etc. But I have been in love with this idea for awhile and would like to hear how or why this won't work, or if it might. Check out this product here:

www.behringer.com/EN/Products/V-AMP2.aspx

I see tube pre-amp processors for vocals in the Musician's Friend catalogue all the time and think that this might be a big next thing.

[Sandbagger]

Oct 7, 2010 2:39:08 GMT -5 midnight said:

Thanks for the explanation on the mod limiting for the older radios. I only knew about the clamping technique. I don't love the sound of clipped radios and agree with you on the key being tonality.

CB Brown, thanks for the battery tip; I will keep that in mind.

I have a Behringer V-Amp 2 electric guitar processor/amp modeler that I am convinced would be a killer way to not only boost audio gain on a radio mic but also to go the usual EQ board approach one better by introducing a zillion combinations of amplification approaches from the clean tube preamp that would make a good starting point and onward through Vox- or Marshall-style, etc. guitar amp tonality (running a voice through it, not a guitar of course) and so on. It provides a wide range of cabinet selection combos that change the tone of every amp brand/style selected and there are individual low, midrange and high frequency settings on potentiometers along with a presence control for brightness and a "drive" gain control that switches on and off.

I just can't figure out how one would run it between a mic and the radio, and how to switch the radio carrier on, etc. But I have been in love with this idea for awhile and would like to hear how or why this won't work, or if it might. Check out this product here:

www.behringer.com/EN/Products/V-AMP2.aspx

I see tube pre-amp processors for vocals in the Musician's Friend catalogue all the time and think that this might be a big next thing.

That probabaly wouldn't be my first choice for a microphone audio preamp/EQ/compressor. But it should not be hard to interface it to a radio. The thing you have to keep in mind is that most studio quality audio devices use 600 ohm balanced lines using XLR style connectors. You would have to get a matching "balun" to convert to the unbalanced audio line you would need to drive a radio. You may also need some sort of padding as line level audio is too high for a mic circuit. If this device uses 1/4 unbalanced phone jacks, it'll be a little easier, you just have to watch the line level so as not to overdrive the radio. As for keying the radio, you'll just have to fabricate a TX/RX hand or foot switch, and run the wires independently of the audio wires which will go through the audio processor.

[midnight]

Thanks for the observations on the Behringer idea; it uses 1/4-inch jacks in and out between the guitar and amp, which helps and also has a MIDI in/out multi-pin jacks as well as an AUX input 1/4-inch jack.