[Drake] Opinion on Drake recievers

[Garey Barrell]

Dennis Kippa wrote:

>  Just started collecting Drake radios and wonder how much difference
>  is there between the R4 R4A R4B and R4C recievers. I understand the
>  C line is most valuable but how much better is it???. And was the R4
>  so bad they had to come out with the A B and C line or was it mostly
>  done for sales .
>
>  Thanks Dennis kw5g
>
The C Line is not necessarily "better". The 4 Series through the R-4B 
used L-C filters in the IF. This type of filter has gentler slopes, 
which means that nearby signals are still heard, just at reduced levels. 
The crystal filters are steep sided, more like the crystal filters in 
today's receivers.   Personally, I prefer the L-C filters for all except 
heavy duty contest use. I like to hear what is going on around my 
frequency, instead of "listening with blinders on"...  Up through the 
R-4B, all filter B/W (400, 1200, 2400 and 4800 @ -6 dB) are standard.

Drake didn't do much for "sales".  They changed models for technical 
reasons, primarily to add solid-state circuitry where appropriate, and 
for ergonomic improvements. 

The R-4 was a "natural" progression of the 2-B.  Similar circuitry, 
triple conversion, IF filtering at 50 kHz with passband tuning, smooth 
AGC, and decent audio.  The main improvement was the linear PTO and dial 
mechanism, (with 5 kHz marks on the illuminated main dial and 1 kHz 
marks on the tuning knob skirt,)  and the introduction of a matching 
transmitter that would transceive.  The circuitry was almost exclusively 
vacuum tube based.

About a year later the R-4A was introduced.   There were two major 
versions of the R-4A, an early version with 13 tubes, and almost 
identical to the R-4.  There were some minor circuit improvements, the 
most significant was to change the PTO from tube to transistor, 
improving the stability of the receiver.  The late version was about a 
year later, and replaced the tube based product detector and agc stages 
with solid state devices.  This reduced the tube count to 11.  The color 
coded carrier oscillator crystals were introduced late in this series to 
improve the transceive alignment stability over temperature.

The next year, 1967, the R-4B was introduced.  There were at least four 
"versions" of the B over the next 6 years.  Each version converted one 
or more stages from tube to solid state.  By the end of this series, 
only the stages carrying RF or IF signals were still tube based.  The 
low level audio stages were solid state, and only the AF output stage 
was tubed.  The PTO was converted from bipolar to FET for further 
stability improvement, and a divide by four was added to the crystal 
calibrator to provide 25 kHz markers. 

Some say they prefer the early R-4A to the R-4B because the tube type 
product detector in the R-4A is "cleaner". 

The C Line was a major change.  The L-C passband tuner was replaced with 
a 2.1 kHz crystal filter.  The noise blanker was an option, (currently 
~$125 and up, IF you can find one,) and optional filters are available 
for 250, 500, 1800, 4000 and 6000 Hz.  All but the earliest R-4C will 
accept up to three additional filters, plus one AM filter.  Passband 
tuning is retained, and tubes (6) are used in the RF and IF stages.  The 
audio output stage is solid state.  The illuminated dial had two discs, 
one with 25 kHz marks and the other with 1 kHz marks.  The C model was 
produced for another six years.  A total of about 30,000 of the "4 
Series" receivers were produced over 15 years.

The T-4 series transmitters are all pretty much the same, the T-4X had 4 
pole crystal filters while the T-4XB and C had 8 pole filters. The
later ones therefore had slightly better carrier and unwanted sideband 
suppression, neither of which has ANY effect on CW operation.

ANY 4 series receiver will transceive with ANY 4 series transmitter, mix 
and match. There are minor things like the B line had a neon indicator
light under the dial to show which PTO was controlling in transceive 
while the C line just turned the dial lamps on or off. The R-4 and R-4A
had neither, so you had to look at the switch!

My opinion..... The R-4B is probably the best receiver overall for 
day-to-day, casual hamming.  It has great audio, smooth AGC, and all the
filters and noise blanker are built in. The L-C filters are not quite as 
"drop off the table" selective, but I prefer that for casual QSOs.   The 
R-4C has poorer audio, a little harsher, the "better" (?) crystal 
filters are extra, and the noise blanker is extra. There are aftermarket 
mods to further improve the "single signal in HUGE pileup" operation 
typical of major contest operations. There are also mods to replace the 
tube third mixer with a SS replacement and a replacement audio output 
stage and power supply.

If you want to read more on the Drake equipment, take a look at the 
"Drakemod 6" file at:

<http://www.zerobeat.net/drakelist/drakemod/drmodtoc.html>

I'm away from home today, so the above is from memory.  I may have 
missed some, but this is the general idea.  I'm sure others will come up 
with somethig I've missed!!

73, Garey - K4OAH
Atlanta