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 Post subject: Drake R-4B
PostPosted: Dec Mon 04, 2017 2:03 am 
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Location: Costa Mesa, California
I purchased a Drake R-4B a few weeks ago that came with the admonition, "Available for sale is a Drake R-4B, serial number 16032G, transceiver. He notes that it is important that you do not turn the radio on!" I see something like that and you can just hang a sign on it with my name attached--because I am buying it. I really have almost no use for working radios. Besides--radios that blow fuses are a lot cheaper.

This R-4B is very clean, which is rare for these copper chassis radios. I went to work on it and changed out the electrolytics. There were four wires in the rear behind the calibrator board that had been added to--which made me wonder what went wrong in the past. The spices did not have insulation, so these were more problems waiting to happen. I cleaned that up. After finishing the filter cap, I checked that the 4 terminals did not have direct continuity to ground--and one of them did. This led me to the power supply rectifier diodes. Both looked burnt and one was definitely bad-so those got changed to 1N4007's. I almost always leave the small two-wire cord on these Drakes because it is a such a signature look for the radio. The fuse was blown so I put in a new one. I replaced the lights with blue LEDs. I buy these from Titan Pinball for 38 cents each. Yes, they are same exact lights selling on eBay for $10 each or more. I just love the look of a Drake radio with blue lights. What I don't like is previous owners slathering a bunch of axel grease on the PTO gearing. I spent a little time trying to clean that up--spraying contact cleaner and using a Q-tip to remove as much as I could. The grease always seems to dry out hard and make the dial difficult to turn. Another problem is when it gets hot and migrates to other areas--not good. One product I favor for lubrication--if any is needed at all--is bicycle chain lube--the wax type that doesn't gather dust and is pretty benign.

With the radio restoration complete, I turned the switch and on came the blue lights. After warming up, the speaker began to hiss. I went through the alignment procedure--although it was very close already with the dial being perfectly aligned. What I never figured out was where "test point 3" is located. 50 KHz Oscillator--"Connect alignment load from pin 5 (plate) of V5 to TP3 on the 25 KHz calibrator printed circuit board (see Figure 13.)" This is the BFO adjustment for T11 to align with the 50 KHz IF. I never found TP3 on the Figure 13 page or on the radio printed circuit board. The LSB and USB seemed to be pretty well lined up so I moved on to the next instruction. It just seemed odd to me that Drake never caught that the instruction referred to TP3 and there was no TP3. I think a person could just inject a 50 KHz signal at the grid of V5, set the Passband knob to the middle of whichever crystal filter position selected and adjust T11 for zero beat--but maybe I am wrong about that. I didn't try it.

As far as my opinion of the R-4B--it has a nice notch (not as good as the Collins 75S-3), a noise blanker, good frequency range coverage--500 KHz per band, option for additional ranges, a good filter, and is able to pair with a transmitter for transceiver operation. Faults--a little on the noisy side.

Norm


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 2:18 am 
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Joined: Sep Sat 06, 2008 3:04 am
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Location: Benton City, WA
Norm Johnson wrote:

As far as my opinion of the R-4B--it has a nice notch (not as good as the Collins 75S-3), a noise blanker, good frequency range coverage--500 KHz per band, option for additional ranges, a good filter, and is able to pair with a transmitter for transceiver operation. Faults--a little on the noisy side.


Drake 4 line twins are and were my favorite radios! Poor man's Collins as they were known. I also love the TR7. I think the R4B was the best receiver Drake ever made. The R4C actually removed functionality but stayed the same price.


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 2:39 am 
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I have a Collins S-3 line and Drake R-4/T-4X twins from the original through the C line and for DXing/contesting I would easily choose any of the Drake twins over the Collins station. In its favor the Collins S line has very nice styling and it is well constructed but performance is nothing special and those 200 Khz. segments can be a real pain for any competitive operating events.

Drake made some changes over the life of the 4 line to reduce mixer noise but sensitivity is very good for any of the 4 line receivers. The passband tuner can be a pain to align on the R-4 through R-4B models as the tuning slug adjustment can have a little backlash but a bit of patience will result in a perfect alignment. The crystal filter type R-4C doesn't have this adjustment and its electronic passband tuning is as good as any rig I own and far better than most; with good CW filters its ability to knock undesired signals out of the passband is nearly magical. The L/C filtered versions prior to the C line don't have the same sharp skirts but they don't require expensive optional filters and for casual operating the voice audio is somewhat nicer through these "softer" filters. The optional noise blankers Drake sold for the R-4C, SPR-4, later TR-4 line, TR-6, and TR-7 work extremely well but they were fairly expensive new and quite expensive now however they were more sophisticated than the noise blankers in most rigs. The only one I have found that worked better than the Drake blankers for some intermittent line noise I experienced a few years ago was the blanker in my Hy Gain 3750 (a rig produced by Matsushita but better known here as Panasonic). The Drake blankers are very good at reducing noise.

Best alignment for any of the 4 line pairs will occur with the receiver and transmitter fully cabled together during alignment and this alignment method should result in insignificant differences in receiver gain and transmitter output when switching between the various frequency control settings.

Although on paper the later R-7 receiver should have some advantages over the R-4C receiver I still would rate my C line twins as better for weak signal CW work over my later TR7A/R7 setup. For best performance a fully optioned out 4C line was the best Drake had but the R4B was still heads above most of the competition and is still a great all-mode receiver today. Add an external audio filter to your R-4any receiver output and you will have a receiver that will serve you very well even if it is MANY years old at this point. And for those who enjoy the smooth audio of the R-4B and before the Drake R8 series receivers went back to L/C filtering and those are still nice receivers.

Rodger WQ9E


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 3:32 am 
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Location: Santa Rosa, CA
Norm,
Also a 'buy it broken' person. Not just because they are cheaper
but also fun to fix up and learn something in the process.
New/working/guaranteed radios are for wimps. ;-)

I'm deep in the bowels of a TR4C myself and just rebuilt the dial
and gear assembly. There should be absolutly NO lubricants on the
nylon gears or the brass piece that fits over the PTO shaft.
The reason is the nylon will, over time absorb some of the
lubricant and swell. Sure enough someone had lubed the
sticking gears on this thing and the tuning knob was hard to
turn. Its a bit of a PITA to do but its worth the time to remove the
dial and gear to clean them up. Made a big difference.
You'll need a beefy set of snap ring pliers.

One problem I'm still having is the PTO shaft can be moved up and
down quite a bit. Far more than the R4C, T4XC and a couple others
that use the same arrangement here. Might be missing a bearing.
Ugh!
Steve


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 3:50 am 
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Joined: May Tue 16, 2017 3:03 pm
Posts: 99
Location: Potomac, MD 20854
rsingl wrote:
The passband tuner can be a pain to align on the R-4 through R-4B models as the tuning slug adjustment can have a little backlash but a bit of patience will result in a perfect alignment.

Rodger WQ9E


Truer words have never been spoken. Also, FWIW, I never use my 4 line in transcieve mode; I just can't get used to that 1000 Hz sidetone shift. WAY too high for me. I prefer 400 Hz, but there is no easy way to fix that. But I can SPOT a station in 3 seconds, so not a problem. That is a beautiful radio you got there. If you like to SWL at all, get optional crystals. It is my best SWL radio (even though they are in 500 kc slices, who cares).

paul


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 3:55 am 
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Location: Costa Mesa, California
zarco wrote:
Norm,
Also a 'buy it broken' person. Not just because they are cheaper
but also fun to fix up and learn something in the process.
New/working/guaranteed radios are for wimps. ;-)

I'm deep in the bowels of a TR4C myself and just rebuilt the dial
and gear assembly. There should be absolutly NO lubricants on the
nylon gears or the brass piece that fits over the PTO shaft.
The reason is the nylon will, over time absorb some of the
lubricant and swell. Sure enough someone had lubed the
sticking gears on this thing and the tuning knob was hard to
turn. Its a bit of a PITA to do but its worth the time to remove the
dial and gear to clean them up. Made a big difference.
You'll need a beefy set of snap ring pliers.

One problem I'm still having is the PTO shaft can be moved up and
down quite a bit. Far more than the R4C, T4XC and a couple others
that use the same arrangement here. Might be missing a bearing.
Ugh!
Steve



Steve,

There is an end play adjustment below the PTO can that allows you to tighten the play. You can reach it with a long allen wrench without removing the PTO if you know just where to stick the wrench.

Norm

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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 4:44 am 
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Location: Costa Mesa, California
This is from a post a few years ago:

"This radio had a very wobbly dial when I got it. At first it appeared to be missing one of the ball bearings--that was how loose it was. After much work, I removed the PTO and took off the electrical section. All of this was unnecessary. There is a set screw adjustment that tightens the dial shaft end play. It is accessed with the can removed. A long shaft 3/32" Allen wrench is inserted through a hole in the phenolic board the coil is mounted on. This hole is below the coil so you can't see it, but it is there. Then the wrench is turned and a set screw tightens any play in the threaded shaft. The other end of the shaft pushes against the bearings in the race."

Norm

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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 3:05 pm 
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I believe some of the best general notes on the Drake 4 and 7 line gear are contained in the 1996 document simply named "Drake Mods"; there is a section at the front that concisely describes PTO maintenance and adjustment: http://zerobeat.net/drakelist/drakemod.html

Rodger WQ9E


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 3:12 pm 
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Location: Santa Rosa, CA
Thanks for the tips guys. Your timing is perfect!
Steve


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 5:30 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 68
Very nice looking R4B Norm. After alignment "and a bit noisy"; just curious what sensitivity measure did you see for either CW or AM? Any setting as long as you specify. Trying to bench mark with the one I am working on. Thanks, Alan W4AMV


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 5:49 pm 
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Joined: Sep Sat 06, 2008 3:04 am
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Location: Benton City, WA
You will find WB4HFN's site to be invaluable at:
http://wb4hfn.com/DRAKE/


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 5:57 pm 
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Location: Costa Mesa, California
Alan,

I did most of my alignment of the RF and Mixer coils with 15 microvolts at the antenna. This registered 5 to 6 plus on the S meter and allowed for an easy time finding the peaks. 5 microvolts still provided a good signal to noise ratio, but I suspect that at 1 microvolt, the noise would start to drown out the signal. AM would be a weaker response.

Norm

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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 6:32 pm 
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Very good Norm. Thanks! That is pretty much in line with what I am using. And thanks on the post of the Drake link.


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 Post subject: Re: Drake R-4B
PostPosted: Dec Mon 04, 2017 7:11 pm 
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In CW/SSB mode with narrow (.4) selectivity a signal well under 1 uv should be clearly audible.

If overall gain seems sufficient then V1 and V2 are the most likely suspects for low sensitivity. First check voltages to rule out an out of spec screen, plate, or cathode resistor and then consider substituting a different tube. A tube tester is useless in determining actual performance of these tubes operating in the upper HF range.

The 6HS6 tube is expensive and several people haver reported that the common 6AH6 makes a good replacement so if you have low sensitivity and no access to a 6HS6 I would definitely try that as a test. The R-4C might be marginally more sensitive than the earlier receivers, mostly due to its reduced noise bandwidth with a 250 hz. filter, but any of the 4 line receivers have enough sensitivity that they will be noise limited by your environment and not the receiver itself as long as they are working properly.

There is some wideband mixer and IF noise in these (and almost every vintage receiver) that don't reduce the ability to receive weak signals but the noise can impact listening pleasure. Especially for CW an audio filter does wonders. One advantage of many vintage solid state receivers is a lower amount of overall noise compared to their vacuum tube counterparts; an advantage that was greatly reduced when all of the digital circuitry was added. My first experience with the Kenwood 599A twins was at Field Day in 1975 and I thought the R-599A was deaf on 10 meters compared to the Heathkit SB-102 I owned because of the lack of noise. That impression was corrected when I started tuning across weak signals that popped out like they never did on my SB-102 and the Kenwood twins remain one of my favorite vintage setups to this day. The original 599 had some overload issues, corrected by the much improved front end of the 599A which is electronically identical to the darker 599D. An R-4C will still outperform a Kenwood R-599D under tough conditions and the Kenwood receiver lacks the very nice Drake passband tuning system but the Kenwood receivers came with all filters, noise blanker, and a FM detector standard with 6 and 2 meter converters as the only internal options.

Rodger WQ9E


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 Post subject: Re: Drake R-4B
PostPosted: Dec Tue 05, 2017 1:20 am 
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