Garey Barrell
Thu, 24 Apr 2008 16:00:08 -0700
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- David - I just had this conversation the other day...! :-)I don't think anyone knows for sure, but I believe the AF board change was made around s/n 6000 or so. Early 1980. According to Bill Frost, the 1496 was originally designed into the R-7, and was then adopted as a cost saving measure in the "second generation" TR-7. The IC replaced a hand wound toroid and a couple of alignment problems. It's pretty easy to spot in a TR-7, as it's right at the top "right" corner of the 2nd IF/AF board at the rear of the card cage. Version 1 has the toroid up there and a little U-shaped shield (yet another "costly" item not needed with the IC) while the Version 2 board has the IC and a few resistors. Personally, I doubt if you would notice the difference by ear. I have a couple of each, and can't say that "I" can hear the difference. Yeah, the 1496 has a wider dynamic range than the two diode PD, but the AGC kinda eliminates the advantage of wide dynamic range! I think it was purely cost saving, and a fancier set of specs couldn't hurt! :-) A dutch ham did a conversion by removing all the parts associated with the Version 1 and putting the 1496 on a small piece of perfboard mounted just above the original board.
<http://home.wanadoo.nl/cmulder/drake.htm#bookmark3> I'm sure we'll hear other opinions!! :-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs <www.k4oah.com> David & Chris Drake wrote:
Hi all,Couple questions: Is there a significant performance difference between the first and second version 2nd IF/Audio boards?. I believe Drake changed to the newer version along the time the R7 came out, but not sure exactly. And: If the answer to the first question is affirmative, then is there anyone out there who has performed the upgrade on and early board? Good results?Thanks, David Wd9cmd
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