"Donley" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Garey,
Remember, I said 'mildly disagree' based on age and memory or lack of
memory. Thanks very much for the further information and for verifying that
it did not get into the manuals. It seems as though Drake would have to
select all five crystals for the transmitters. Did they do that and only
stripe one of the crystals in the set? I have not yet opened my T-4XB and
R-4B to verify that the crystals match the letter after the serial number. I
also have a C-line set that I use more often, so have not been too concerned
about the B-line.
Thanks again for the explanation.
73
Dick
KC9UB
----- Original Message -----
From: "Garey Barrell" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, October 15, 2007 11:22 PM
Subject: Re: [drakelist] Color stripe on Carrier Oscillator and BFO crystals
in T-4XB and R-4B
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist
gang
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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
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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
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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
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