Paul -
You have covered the differences pretty well. 'Value' of the different features is in the eye of
the beholder, which may sway a purchaser one way or the other.
Paul Christensen wrote:
For the past few weeks, I've been comparing receive structures between the Drake 4 series and
Collins 75S-3 series. I'm surprised by the similarities - as well as the differences.
Some obvious differences:
- Mechanical IF filter versus crystal or LC filtering;
L/C filter preferred by some, including me, for day to day hamming purposes. The distortion of very
steep-sided crystal filters can be very tiring. I also like to know what is going on around MY
frequency.
-160m coverage ability;
Simple crystal addition for the Drake.
- Tunable BFO versus PBT;
PBT is preferable, since you essentially move the 'window' around the signal without changing pitch,
but is difficult with a fixed filter. Look at the mechanical nightmare of the 75A-4.
- Q Mult in 75S-3.
Nice feature, handy in a few situations.
Similarities:
- PTO VFO with 1 kHz dial markings;
- Preselector (similar octave structure?);
- Crystal 1st LO (unlike early JA receivers during the same time period);
- Audio power and AF driver stages similar to R-4B;
- Extensive use of RCA jacks, including RF IN;
This is the one that gets all the flack. Really unjustified, as the RCA jack is every bit as good
as the UHF or BNC connector at the frequencies involved. It does suffer some from mechanical
stability, but typically not a problem unless you insist on using RG-8/U with three adapters hung
right on the RF Output jack! IF you do a LOT of setup/teardown of your station, these connectors
do weaken, and in that case I would suggest short pigtail leads left in the RCA jacks with a more
robust connector on the other end.
Collins, like Drake, used PBT in the 1950s and I'm curious why it was abandoned in the S line.
Perhaps too complex to use among commercial/military/amateur users? In essence, the least common
operating denominator wins?
See 75A-4 mechanicals.
Both series use the chassis for the filament return, although Collins used four (!) heater lines
in the 75S3.
The filament wiring was dictating by the necessity of operating from multiple power supplies,
requiring different series/parallel combinations to allow for filament voltages up to 28 VDC.
I found Collins' treatment of the headphone jack quite interesting. They use a resistive divider
network to load the output line during periods of high Z loads. Seems wholly unnecessary given
that the 4-ohm transformer tap is routed through the H/P jack's N/C contacts and the 500-ohm tap
makes use of the divider in which one resistor is bypassed during insertion of headphones.
My recollection of the S line tuning feel is sketchy but I recall a superbly designed VFO tuning
mechanism onto the PTO -- probably at least as mechanically well designed as the those found in
the Drake 4 series?
The PTO is where Collins superior mechanical construction is most obvious. Nice, solid machined
case, gear driven dial with 'cute' fractional dial plates. Probably the best single feature of the
Collins. There is a story floating around that said that Collins bought one of the very first
TR-3's with the Drake PTO, and when they opened up the PTO housing they found a note that said, "
Pretty neat, huh Art? Bob Drake." The Drake PTO is much less mechanically robust, but there is
elegance in simplicity of design and execution that results in essentially identical performance. I
have found a Drake PTO or two that did NOT meet the "Better than 1 kc when calibrated at nearest 100
kc point" or "3 kc end-to-end" specification, but in each case there were at least indications that
someone had been 'fixing' inside them. The "100 cycle stability after warm up" was outstanding in
it's time, and still isn't too bad today.
The Collins is marginally quieter as a result of lower B+ producing less thermal noise, but I don't
think there is anywhere in the world where a receiver isn't limited first by externally generated RF
noise, so not really any 'value' unless you have a screen room for your ham shack.
Perhaps the Collins S line has a slight edge with quality of construction and components although
I've not taken a look at whether the 75S-3 uses ceramic switch wafers versus Phenolic -- and
whether they used Teflon harness wiring (where Drake fails).
It's been a while since I was inside my S-Line, but I believe they used some 'plastic' wafers along
with some ceramic, similar to Drake. The Collins only went to Teflon wire late in production, early
used a thermoplastic type, although it was MUCH less heat sensitive than the Drake wire. I've NEVER
seen wire that heat sensitive in ANY other equipment. Drake used the small PC boards as "component
accumulators", with little regard for what was on what board. Most had more than one circuit
'section' on it, basically just terminal strips to hold components whose leads 'wouldn't reach'!
Collins used a few of the 'turret sockets', the phenolic posts that stuck up from the bottom of tube
sockets with radial terminals for tie points. Drake used a few of them in the TR-(any). I don't
know of a real advantage to either method, but the turrets sure are harder to photograph for my CDs!
I have nearly no operating time with an S line and I was considering a purchase. But based on
what I'm seeing in the schematics, I'm not impressed enough to unload my bank account for a S
line. This may seem like a "trolling" exercise to some, but I find the comparison between the
two products to be very interesting especially when comparing cost and evolution of their product
lines.
Back in the 60's, I worked part-time for a Ham distributor in Huntsville, AL after my day job with
NASA. We had multiple stations set up, with a dipole and tribander on the roof of the building. I
had previously owned a Drake 1-A and currently had a 2-B, so was somewhat biased, BUT when the Drake
4 Line was first out I set up each of the Drake and Collins 'pairs'. This was a '5-9 pm' "job"
weekdays, so there was quite a bit of 'dead time' which allowed hours of comparison between the two
products. Back then, the major manufacturers offered ONE set of their product to 'sales people' at
50% of list price. The distributor paid 75% of list, so it was a pretty good discount, and put both
within reach. The Collins was almost 40% more than the Drake, making a real incentive to determine
relative value. I LOVED the feel of the Collins, the 'camera leather-grained' front panel, sturdy
knobs and handy lift top cabinets. The Drake seemed kind of crude by comparison, with thin
silk-screened, sheet metal punched panels, square cornered cabinets, and open back. After many
hours of comparison though, I just could not justify to myself the price differential. Yeah, there
was the visual factor, and of course the 'cachet' of the COLLINS badge on the front, but ...
So over the last 50 years I've stuck with Drake, own(ed) at least one of each 4 and 7 Line models,
and suffered the 'slings and arrows' of the snooty Collins owners.. :-) As I have said before, I
have an S-3 Line and 75A-4 in the closet, or perhaps the garage, for at least the last four years,
and the B-Line is on one desk, the 7-Line on the other, and (cough) a TS-940SAT on another. The
B-Line is the one I turn on when I come home, the R-8A is most often on the BC band.
Thoughts on the matter very much appreciated.
Paul, W9AC
Can't say you didn't ask for it!! :-)
--
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
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