----- Original Message -----
From: "Paul Christensen" <w...@arrl.net>
To: <drakelist@zerobeat.net>
Sent: Tuesday, June 14, 2011 7:30 PM
Subject: [Drakelist] Collins and Drake Compared
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;
-160m coverage ability;
- Tunable BFO versus PBT;
- Q Mult in 75S-3.
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;
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?
Both series use the chassis for the filament return,
although Collins used four (!) heater lines in the 75S3.
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?
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). 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.
Thoughts on the matter very much appreciated.
Paul, W9AC
I would be interested in hearing from others who have
both systems.
I do find Drake gear difficult to work on because of
the very short leads, use of component leads as connection
wires, and low-temperature insulation. I just have trouble
with the very confined spaces. There is good reason for the
short leads and it shows up in the performance of the gear,
nonetheless, its difficult to work on. I don't know that
Collins is any better.
What I remember is that Collins made a big splash with
the S line stuff when it came out and then Drake blew them
out of the water with about similar performance (sometimes
better) at maybe 2/3rds the price.
--
Richard Knoppow
Los Angeles
WB6KBL
dickb...@ix.netcom.com
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