Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Dick -
No problem.... Just don't ask me what I had for breakfast yesterday!
:-)
Don't feel bad, I asked Bill Frost about the color coded crystals a year
or so ago and he didn't even remember that they had them! Of course,
it's hard for us to realize that it's was a "job" for him the last 40
years......
ONLY the Carrier Osc and the Second Conversion Osc are involved, because
the Premixer signal (Band Osc and PTO product) is piped from the
"control" unit to the "slave" unit. The Premixer signal stability
affects the absolute stability of the pair, but only the two "striped"
crystals affect their relationship to each other in transceive. Since
typically the receiver was used to control transceive, the temperature
variation from R to T in the transmitter was eliminated as long as the
Carrier Osc stayed put. So as long as the two crystals are "stable" in
relation to each other, yes, you might have to retune to stay on another
station, but even if you do, when the transmitter comes back on it will
be ON the receiver frequency.
Keep in mind that 30-40 years ago _*stability*_ was not what it is
today, by at least an order of magnitude. Many hams were still using
Hallicrafter's receivers that "boinged" up or down the band if you
bumped the desk or even walked across the floor. Drake and Collins were
orders of magnitude above the typical gear of the day, most of which was
designed after WW II, some even earlier.
The C Line eliminated the problem completely with the CAR OSC cable.
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,
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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