Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- Al -
I was just going from memory, but I believe there were some changes around the AGC application to the Noise Blanker. There were probably others but would take a stage by stage comparison of the schematics to say for sure. Honestly, I never was able to tell any difference in any of the B receivers, even as far back as a "late" A. They were so similar. I'm beginning to stir on either the B Line or TR-4(C) for another CD, which would certainly reveal the differences. I doubt you would be able to tell the difference between the 8000 and 10501 models. Overall condition would be much more important to me between the two.
73, Garey - K4OAH Atlanta
Drake C-Line Service Manual <http://hr99.home.mindspring.com/R-4C_Servicez/>
n7ioh wrote:
Hi Garey, the minor AGC changes on the s/n 10501+ I would assume could be made to the 2nd group s/n 8000+ without much problem if desired? Do you know what affect the AGC change had on this receiver?
Thanks, Al, N7IOH
Garey Barrell wrote:
Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang
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Al -
There were at least three documented "versions" of the R-4B. I haven't fully documented the differences but....
1. s/n 7000+ - Bipolar PTO, 0B2 VR tube, 6HS6 Premixer and 1st Mixer, SS HFO, BFO. PD, AM Det, AGC and AF preamp. RF Amp through last IF Amp + Noise Blanker all tube.
2. s/n 8000+ - FET PTO. 0B2 removed.
3. s.n 10501+ - Minor AGC changes.
Aside from a slightly improved temperature stability with the FET PTO, little or no discernible difference among all three. All used the "color-coded" BFO crystal for improved stability of the "transceive alignment" adjustment with the T-4XB.
73, Garey - K4OAH Atlanta
Drake C-Line Service Manual <http://hr99.home.mindspring.com/R-4C_Servicez/>
n7ioh wrote:
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n7ioh <[EMAIL PROTECTED]> made an utterence to the drakelist gang
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I know that there are some differences in the R-4C's noted by serial numbers. Are there any differences in the R-4B's and if so what are they by serial groups? I have decided to add one to my station and thought it better to ask first before I buy one.
Thanks, Al, N7IOH
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