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Post by 321 treeclimber on Dec 12, 2018 8:43:10 GMT -5
Since I've gotten into tube radio on 11meter i noticed that my comstat 25a or my robyn exec, Doesn't respond to power mics like any of my newer radios do. Any of my d104s or turner mics boom or scream on my galaxy's and connex,cobras and the like,all transistor solidstate....anyone notice this too or am i not wiring correctly? Seems like,power mics act just like a stock mic that you can "turn down". Not up
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Post by 2600 on Dec 12, 2018 12:32:46 GMT -5
The Lafayette Comstat and the Robyn use a modulator circuit called a "Heising" modulator. It saved the vendor money, but has a drawback. Trying to push the radio beyond 100 percent modulation doesn't get "loud", but instead just sounds flat.
Those radios just don't have the audio power to get large the way most solid-state radios can do.
They were designed to reach 100 percent modulation, and that's all. They'll sound pretty smooth until you push them too hard.
73
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Post by 321 treeclimber on Dec 12, 2018 13:47:25 GMT -5
Big 10-4 ! That saves me a lot of grief ! I thought i did something wrong.they sound great but i figured my turner 2 would make them blast....nope. at least i understand now. Thank's for the schoolin and relief. treeclimber
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Post by 321 treeclimber on Dec 12, 2018 13:48:21 GMT -5
Big 10-4 ! That saves me a lot of grief ! I thought i did something wrong.they sound great but i figured my turner 2 would make them blast....nope. at least i understand now. Thank's for the schoolin and relief. treeclimber
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Post by SIX-SHOOTER on Dec 12, 2018 21:44:18 GMT -5
The Lafayette Comstat and the Robyn use a modulator circuit called a "Heising" modulator. It saved the vendor money, but has a drawback. Trying to push the radio beyond 100 percent modulation doesn't get "loud", but instead just sounds flat. Those radios just don't have the audio power to get large the way most solid-state radios can do. They were designed to reach 100 percent modulation, and that's all. They'll sound pretty smooth until you push them too hard. 73 Strange,I get some great audio reports from my Robyn 240D,Teaberry Model T,Gemtronics GTX-5000,& ROBYN T-123B with the amplified D-104? They are all far louder with the D-104 than with the stock hand microphones & the 240D & GTX-5000 are downright BOOMING LOUD on transmit. SIX-SHOOTER |
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Post by 321 treeclimber on Dec 13, 2018 8:05:13 GMT -5
Hmmmmm...do they all use the same circuitry. I know the chassis are the same,gemtronix anyway.but my silver eagles,tug 8s and turner 2s and 3s all react the same.yes,louder than unamplified but now where near the audio power as when on solidstate radios!i even tried my shure"bad ass powerhouse"desk mic with the same results.
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Post by 321 treeclimber on Dec 13, 2018 8:10:43 GMT -5
Also these radio are both stock aside from being recapped. If there's something i can do to get more I'd like to try. Otherwise i concur with 2600 on the symptoms
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Sandbagger
Administrator/The Boss 
Posts: 6,247 
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Post by Sandbagger on Dec 14, 2018 17:06:43 GMT -5
Since I've gotten into tube radio on 11meter i noticed that my comstat 25a or my robyn exec, Doesn't respond to power mics like any of my newer radios do. Any of my d104s or turner mics boom or scream on my galaxy's and connex,cobras and the like,all transistor solidstate....anyone notice this too or am i not wiring correctly? Seems like,power mics act just like a stock mic that you can "turn down". Not up I'm not sure I agree that the Panasonic chassis radios don't "respond" to a power mic. No, they don't have that piercing loud splattery overmodulation, but they will get decently loud provided that you don't jump out the plate limiting resistor for increased carrier power. The modulator can take a 3 watt carrier and 100% modulate it, but anything above that 3 watt level and the modulator will fall short. I dropped the carrier power down to 2.5 watts and I can get a tad over 100% and that's good enough for me. The locals all tell me it sounds nearly as good as my "better" tube rigs (Browning, Tram, Sonar) using the same D104 mic. But our group doesn't subscribe to that "all knobs to the right" mentality, and none of my radios exceed 100% modulation by any great amount (unless they didn't come with modulation limiters), so they tend to all sound frighteningly similar..... |
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Dec 14, 2018 17:55:14 GMT -5
Hmmmmm...do they all use the same circuitry. I know the chassis are the same,gemtronix anyway.but my silver eagles,tug 8s and turner 2s and 3s all react the same.yes,louder than unamplified but now where near the audio power as when on solidstate radios!i even tried my shure"bad ass powerhouse"desk mic with the same results. The later model Comstats and other Panasonic chassis radios have a modulation limiter adjustment inside the radio (Lafayette calls it a "Range Boost" adjust). If that is set too tight, it will clamp your audio below 100%. You can crank that up and it should improve your "loudness". |
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Post by 321 treeclimber on Dec 14, 2018 18:23:42 GMT -5
Roger that sandbagger.i agree with your outlook on being more loud than necessary. Just my curious observation and fear that i may have wired them wrong.im very satisfied with reports on these fun radios.my kids are learning all kinds of radio history by being in the radio room with me too. Hey any thoughts about the Robyn's "instant on"
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Dec 15, 2018 11:37:11 GMT -5
Roger that sandbagger.i agree with your outlook on being more loud than necessary. Just my curious observation and fear that i may have wired them wrong.im very satisfied with reports on these fun radios.my kids are learning all kinds of radio history by being in the radio room with me too. Hey any thoughts about the Robyn's "instant on" Most of the Panasonic radios had some sort of "standby" or instant-on feature. Usually the volume control included the main power switch. But on the squelch control was the "standby" position. Turning the radio on with the main power switch, but leaving the standby switch off, would supply power only to the tube filaments, while the other power supply voltages were off. This allowed the operator to have the radio come to life instantly, similar to solid state radios, by using the standby as the on/off switch. I used to do that back in the 70's with my Comstat. Some versions of the Panasonic chassis rigs eliminated the on/off switch, and moved the standby switch to the volume control. As soon as you plugged the radio in, it was in "standby" and the tube filaments would light up. The main on/off switch would then act as the standby switch did in the other versions. I wasn't fond of that arrangement, as I didn't like to leave the tubes hot 24/7/365.I liked having the ability to turn the rig completely off if I wasn't going to be using it for several hours. Of course, you could always unplug the radio to achieve the same result, but that was more cumbersome than just turning a knob. |
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Post by 321 treeclimber on Dec 15, 2018 16:36:05 GMT -5
Yep feel the same way. My robyn was altered by previous owner with a wired in kill switch that basically mimicked the 25a style standby but it created a hum. So i deleted that and just plug it into a switchable(on off)power strip.
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Post by 321 treeclimber on Jan 2, 2019 7:43:28 GMT -5
Ive done everything prescribed and i got all these Panasonic chassis radio will give. Guess they are what they are, good sounding local talkers. Thats it. 321
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Post by grimace on Jan 2, 2019 11:22:44 GMT -5
a local uses hifi gear on a 240D and it is loud and the best sounding 240d I have ever heard
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Post by 321 treeclimber on Jan 2, 2019 14:05:19 GMT -5
Love my yellowbird and my 25a they have a home here for life . 321
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