Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
----------------------------------------------------------------------
Dick -
Well, you're certainly welcome to disagree, but I "was there"! :-)
They were never mentioned in the manuals, but the program was initiated
when Drake tired of the complaints about the Transceive Align procedure
not "holding" over time. They determined that the primary cause of the
"drift" was variations in the tempco of the crystals, and initiated an
internal test setup to "select" crystals with similar temperature
characteristics from their regular stock. They were graded into three
different groups and a paint stripe was applied. I have seen at least
two units with "Y" serial suffixes and a Yellow stripe. They must have
been real "outliers"! As I said earlier, it only becomes a problem when
you transceive on SSB because 50 Hz variations or even less are audible,
whereas on CW it's barely noticeable. Also, CW ops are much more
tolerant of slight frequency differences, AND seldom operated transceive
anyway!
Back then, Drake would exchange the crystals at no charge to allow you
to get a "matched" set, and dealers were instructed to sell matched
pairs when they were purchased together. I was selling Drake (and
Collins, etc.) at the time as a "part time" job after my "day job" at
NASA. The program started with the third version of the R-4A, and
crystals were exchanged with T-4X owners. I don't think the serial
number suffix was added to any T-4X transmitters, at least I've never
run across one, but I've seen more than a few with color striped
crystals in them. When the B series came out in mid to late 1967, they
all had s/n suffix letters from the factory.
The only problem with mismatched crystals is variation in the Transceive
Alignment when the room temperature changes and/or as the pair warm up
from a cold start. A "worst case" mismatch, which I believe is the
Red/Blue combination, would actually change during a long transmission
from the additional heat dissipated in the transmitter. Again, it was
only noticeable on SSB transceive. Most one-on-one contacts in those
days wouldn't mention a problem, unless it was a "round-table" group
with several participants, and nowadays most everyone is using a
transceiver with RIT and they just follow. I'm surprised you haven't
been accosted by one of the "channelized" guys who don't dare operate
anywhere but on a frequency ending in 0.00! :-)
The problem was resolved completely when the C Line came out by adding
one more cable between units to enable a sort of phase-lock between the
two oscillators.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Donley wrote:
"Donley" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
----------------------------------------------------------------------
Garey and all other Drakelist members,
Below are two quotes from previous emails:
'The letters are a color code for the Carrier Oscillator and BFO
crystals in the Tx and Rx. Ideally, the letters (and color stripes on
the crystals themselves, CHECK!) are the same in Tx and Rx.'
'I want to transceive with this pair so the color code is important.
The R-4B has a red stripe on a crystal next to the crystal calibrator
under the chassis. None of the other crystals are color coded. And the
T-4XB has a red stripe on one of five crystals under the chassis.'
I want to mildly disagree with the concept of these two statements. I
say mildly disagree because I am not completely sure of myself, but
will list my objections (there are only two).
I don't see the importance of matching the color stripe of the Tx and
R. I would think that the Tx or R unit would be tested individually
for drift (+, - or 0) and the appropriate TC compensating crystal
would be inserted to minimize that drift (- TC for + drift,+ TC for
minus drift or 0 TC for 0 or minimal drift). This would insure minimum
drift in either unit. So shouldn't any Tx transceive with any R?
Secondly, I can find no reference in the Drake manuals to the
requirement of matching Tx and R colors. In fact, I can find no
reference to the color stripe at all in the manuals that I have.
This concept would have put a burden on the seller and buyer of Drake
4B series Tx and R to match the color designation at purchase. I don't
recall (remember it was 30 to 40 years ago) any mention then of this
concept. I have the 4B series Tx and R with two different color
striped crystals, B for the T-4XB and G for the R-4B and do not notice
any problems in transceive.
I do recall seeing written information recently about the color coded
crystals, but I can't remember where. (I just found that article and
it was written by you, Garey).
I will bow to those of more expertise than I have and stand by for any
comments.
Remember, I said mildly disagree.
73
Dick
KC9UB
----- Original Message ----- From: "Garey Barrell" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, October 15, 2007 9:54 AM
Subject: Re: [drakelist] Any disadvantages to using R-4A with T-4XB?
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the
drakelist gang
----------------------------------------------------------------------
Wow! Talk about decisions..... :-)
Both of your receivers are VERY "late" in their respective groups.
Your R-4A is close enough to actually count the tubes. It "should"
have 13 tubes, and therefore the tube type PD, but Drake wasn't
always "perfect" when it came to model changeovers. So I'd be very
interested in how many tubes are in your R-4A, just for refining my
data.
There is an article on the WB4HFN site, but that was also from 40
year old memory also. I "think" the Red crystals were positive TC,
the Green were near zero TC and the Blue were negative TC. The same
color in R an T is ideal, but if I have the colors right you have a
positive and zero combination with the R-4B. The R-4A could be
better or worse, since all Drake did was characterize their standard
crystals in-house, and we have no idea what group the R-4A crystal
would have fallen into! :-) I asked Bill Frost at Drake about this
a few years ago, and he had even forgotten that they "had" color
coded crystals....
Best is to set them up, and try them for a while. Depending upon how
stable your shack temperature is, and how long you let them warm up
before use, etc., you might not have a significant problem. You
could try a "want" for someone with a mismatched pair to swap your G
for an R or your R for a G if you find it to be a problem. A
hint..... You can get an Xcelite 3324 screwdriver which is long
enough to reach the C61 adjustment in the receiver without removing
the cabinet top. If it's not quite long enough, you can shave a bit
off the blade end of the handle. After you put it through the
"proper" hole in the cabinet top, slip a piece of aquarium airline
tubing over the blade end and fit it to the C61 adjuster. You can
probably figure out why I did this 40 years ago!! :-)
My choice, assuming the general condition of the two receivers is
similar, would be the R-4B. The "above the belt" lettering on the A
is difficult to see in normal lighting at best, the same for the
slanted kC dial, and the PTO in use light is handy. The cabinet
paint on the B is tougher also. Actually, if it was me, I'd keep
them both, which is why I have a couple dozen 4 Line boxes........ :-)
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Tom Bowman wrote:
Hi Garey,
Thanks very much for your complete answer. Here's what I found out:
First question is what is the serial number of your R-4A?
The R-4A serial number is 3956 with no letter behind it.
What is the letter at the end of the R-4B serial number?
The R-4B is 15359 with G behind the number.
What is the letter at the end of the T-4XB serial number?
The T-4XB is 10382 with R behind the number.
BTW, I want to transceive with this pair so the color code is
important. The R-4A has no color code on the crystals.
The R-4B has a red stripe on a crystal next to the crystal
calibrator under the chassis. None of the other crystals are color
coded.
And the T-4XB has a red stripe on one of five crystals under the
chassis.
The letters are a color code for the Carrier Oscillator and BFO
crystals
in the Tx and Rx. Ideally, the letters (and color stripes on the
crystals themselves, CHECK!) are the same in Tx and Rx.
My plan is to keep one of the receivers and sell the other. Will
either of these two receivers work on transceive without problems
with the T-4XB?
Thanks for taking the time to read and answer this.
Tom, WA3REY
----------------------------------------------------------------------
Submissions: [EMAIL PROTECTED]
Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost: [EMAIL PROTECTED] - help in body of message
Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net
----------------------------------------------------------------------
