Selectivity of the R-4C crystal filters is better than the R-4B¡¯s 50 kHz L/C filters.?
Sensitivity very similar, maybe slightly better for the C-Line.?
Rob, NC0B?
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On Feb 4, 2025, at 9:59?AM, Bill Losef via groups.io <w.losefsky@...> wrote:
?
Has anyone done a sensitivity / selectivity test between a R4B VS a R4C?
Bill N1WL
On Monday, February 3, 2025 at 08:26:57 PM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
I prefer the C in tight quarters on CW. You can get crystal filters down to 250 Hz stock and 125 Hz if you search. In pileups, these are the equal to newer rigs¡¯ receivers.?
For everyday, casual CW, the B sounds quite nice.?
Understand that the shape factors of the two rigs¡¯ filters are fairly different. Some prefer one over the other.?
The CW subbands aren¡¯t as crowded as they were 20 years ago, so take that into consideration.?
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 15:17, Craig W8CS via groups.io < craig_severson@...> wrote:
Hi Scott, have you read the VE3EFJ "Drakemod" manifesto? If I recall Wayne's verbiage, it's something like this:
?
The R-4B is a terrific receiver out of the box and it does everything well, however you won't get the selectivity of an R-4C. The R-4C stock is a bit of a waste compared to its potential due to some questionable design choices. A properly (Sherwood)
modified R-4C is transformed and is an exceptional receiver.?
?
Others will have a much more technical take than mine. The 4B is great out of the box; the 4C requires some work to realize exceptional potential.?
--
Craig/W8CS
Greenville, SC
|
Re: The mysteriously modified 7077 (and nothing else¡)
Sometime during the production of the TR7 the 470K in series with pin 4 was added to provide the high level input. The three rigs I have all have it. It was also added by the service department to rigs sent in for repair. There was a note added to the owners manual regarding this at some point. On Tue, 4 Feb 2025 15:09:02 +0000 (UTC) "Evan via groups.io" <k9sqg@...> wrote: Yes for the TR-7A and possibly late production TR-7. ?One pin is for "high output high impedance" while the other is "low output low impedance"; ?basically just a resistor between the two pins. ?
On Tuesday, February 4, 2025 at 09:39:44 AM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Indeed.?
I thought I¡¯d heard that there are two audio inputs to the TR7. I¡¯m going to have to look at the service manual, as the owner¡¯s manual only shows pin 4 as n/c. Perhaps this low level element could directly feed the low-level input, if it exists¡
Steve Wedge, W1ES -- 73 -Jim NU0C
|
Have been working on the TR7 CW issue and today I changed the
switching transistor that turns on the 10 volts and off. Before I
changed the PNP transistor when the key is up it showed 1.77 volts
and now it shows 0.8 volts but that seems to be enough to keep the
crystal oscillator running. Got to think this over more and try
something else. Any idea and or suggestions welcomed.
73, Jim VE1RB
On 2025-02-01 16:33, Jim Harris via
groups.io wrote:
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Thanks Jim for the info and I will try and get
back at it tomorrow.?
73, Jim VE1RB
Yes, you want to look at the 2nd IF/Audio board. CW
operation is described towards the end of the text in
section 2-11 of the service manual. In short the CW transmit
carrier is generated by a crystal oscillator that is offset
nominally 800 Hz from the dial frequency. The oscillator is
keyed by Q1103 on this board.
More info on the oscillator is here:
On Sat, 1 Feb 2025 14:17:50 -0400
"Jim Harris via "
<radiove1rb=[email protected]>
wrote:
> Hi once again. I am back trouble shooting the TR7 with
what I hope is the
> last problem. When I switch the mode switch to CW I get
a 1800 cycle tone
> in the receiver that is over S9 in strength. If you
change the frequency
> this tone does not change at all. I have a Version 2,
2nd I.F/Audio board.
> I have not found an explanation of how the CW operation
works but maybe the
> problem is on that board. Anyone got any ideas? All
suggestions appreciated
> and welcomed.
> Thank you, Jim VE1RB
--
73
-Jim
NU0C
|
Re: Drake TR7, TX issue any ideas?
Okay, ground strap added, not much difference, but makes really good sense! Anode on CR1501 RX = close to 0Volt, TX = 11.5Volt Junction CR1502/CR1503 RX = 10.32Volt, TX = Unstable - constant cycle between
~0Volt to ~364mv Drive was all the way down/cw mode, when measurements was done. What you say? Looks okay beside the
CR1502/CR1503 during TX.
Thanks, Michael.
On Tue, Feb 4, 2025 at 12:03?PM Michael Jensen via <kavigal= [email protected]> wrote: Thanks Jim!
I'll get on it asap and keep the thread updated :).
/Michael.
You may need to check your internal grounds, including all screws and any copper fingers attached to boards. As well, the board cage covers need to be attached with all screws, snug but not over tightened. But first add the ground strap to the high pass filter module as shown in the attached photo. This will help with stability.
Also check the predriver gain adjustment pot. In a healthy TR7 with the ALC adjustment set for 150 Watts on 20 Meters you should get close to 100 Watts on 10 and 15. This is normal. The ALC and predriver gain adjustments work together and if mis-adjusted can cause issues.
You may also want to test the PIN diodes. Procedures are posted on the internet and in this group.
On Mon, 03 Feb 2025 08:53:27 -0800
"Michael Jensen via " <kavigal=[email protected]> wrote:
> Hardly been using it for TX until recently, then I notice that on 10 Meter output is close to 2.5 watts..
> Okay, not much.. On 15 meters the current draw is close to 31 amps to produce 100watts! Quite a bit.
> more reasonably 21-22 amps on other bands.
> So went for an TX alignment, if I crank up the pre drive I can get it up to ~60 watts on 10 meter
> obviously not a good scenario and the dr7 board definitely does not like it as the display starts to be all over the place during TX,
> with pre drive fully cranked up 40 Meters the PA self oscillates, not good.
> So my thoughts, something in the pre drive section or bandpass maybe?
> Looking for any suggestions before going nuts down that route.
> Thanks on advance!
> Best Regards, Michael - oz8abr
--
73
-Jim
NU0C
|
Re: Drake R4/T4 rubber feet machine screws
this is what I¡¯ve been using
master-carr
9541k8 listed as thread stud bumper 6-32 thread size 1¡¯4¡± long
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
J e e p
o|||||||o?
A man with one clock knows what time it?is. A man with two clocks is never sure.
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On Feb 4, 2025, at 2:00 PM, VE7PS via < ve7ps@...> wrote:
Yup - 10-24 Common Slot Pan Head IF you want originality.? I can get the?length for you later today.? 1/2" or 5/8" sounds about right.
73 PS On Tue, Feb 4, 2025 at 9:16?AM Steve Wedge, W1ES/4 via ??<w1es= [email protected]> wrote: Pretty sure it¡¯s 10-24.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 10:40 AM, Scott N1IA via ??< soakland5@...> wrote: I am trying to get some machine screws for the rubber feet of the Drake R4 / T4. What size do I need??
Thanks guys, Scott N1IA
|
Re: TR-4C low power output on 15 & 10 meters
If you go this route, be sure that you¡¯re buying the shorter ones. There are some that are too tall to fit in the PA cage.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 14:25, Barry KJ5GQM via groups.io < chasbg@...> wrote:
6GJ5 tubes have been used as a less expensive alternative. ?Do a search and you¡¯ll find some info and can decide if you want to try them.
|
Re: TR-4C low power output on 15 & 10 meters
And it¡¯s not as important to have exactly matched tubes but it is important that they all be the same brand.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 14:23, Dave W7GZ via groups.io < w7gz@...> wrote:
Dave, a quick review of eBay shows several 6JB6/6JU6 going for around $15 NIB + shipping. Perhaps you can find someone with 3 for sale.
?
Dave
|
Re: TR-4C low power output on 15 & 10 meters
6GJ5 tubes have been used as a less expensive alternative. ?Do a search and you¡¯ll find some info and can decide if you want to try them.
|
Re: TR-4C low power output on 15 & 10 meters
Dave, a quick review of eBay shows several 6JB6/6JU6 going for around $15 NIB + shipping. Perhaps you can find someone with 3 for sale.
?
Dave
|
Re: TR-4C low power output on 15 & 10 meters
Yes, I failed to mention that. BIAS is at 0.1 amp.
So, sounds like everyone agrees, it's the finals. That is an easy fix! But rather expensive. Where are folks finding the best deal on new finals?
73, Dave KD5FX
?
|
Re: Drake R4/T4 rubber feet machine screws
Mike is right about the AC-4 small rubber feet?with the stud at 6-32.
Steve is right about the 10-24 screw for the large plastic feet.
PS
Steve and the group
those small rubber feet that screw into the bottom of the AC4 are in fact 6-32 thread. You can get the rubber feet from McMaster Carr, although I don¡¯t remember the part number off the top of my head
On Feb 4, 2025, at 12:16 PM, Steve Wedge, W1ES/4 via < w1es@...> wrote:
Pretty sure it¡¯s 10-24.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 10:40 AM, Scott N1IA via?<soakland5@...> wrote:I am trying to get some machine screws for the rubber feet of the Drake R4 / T4. What size do I need??
Thanks guys, Scott N1IA
|
Re: Drake R4/T4 rubber feet machine screws
Yup - 10-24 Common Slot Pan Head IF you want originality.? I can get the?length for you later today.? 1/2" or 5/8" sounds about right.
73 PS
On Tue, Feb 4, 2025 at 9:16?AM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Pretty sure it¡¯s 10-24.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 10:40 AM, Scott N1IA via < soakland5@...> wrote:
I am trying to get some machine screws for the rubber feet of the Drake R4 / T4. What size do I need?
Thanks guys,
Scott N1IA
|
Re: TR-4C low power output on 15 & 10 meters
If you have confirmed that your idle current is 100mA then I would agree that your finals are tired.
|
Re: TR-4C low power output on 15 & 10 meters
Ok, my readings compensating T9 de-tuning
on 10m. All relatives, of course.
10m 30V 400mA 105W
15m 27V 420mA 135W
20m 28V 390mA 165W
See that with more or less the same "p-p drive level" I got higher
plate current (and higher output pwr).
Note that I modified the wiring around external RX switch: so when
I connect the scope there, there is not any extra coaxial run
between switch and antenna relay (less parallel C).
Seems that up to the 12BY7 things are ok. May be the finals
reached EOL.
73
Marcus PY2PLL.
Em 04/02/2025 13:12, Dave KD5FX via
groups.io escreveu:
toggle quoted message
Show quoted text
This is the same TR-4C that had the bad Xtals which were
fixed by a baking. The problem now is the output is very low on
15 and 10 meters. Someone suggested I test the output on each
band at the output of T9 which is on the driver. So I did and
here is the results. Also, I re-tested the driver tube and the
final, they all checked very good and I did a resistance test on
the driver and finals as per the readings in the manual and they
were all good.
Band? ?T9 out Power out
80? ? ? ?35V? ? ?130 W @ 0.4 amps
40? ? ? ?28V? ? ? ?90 W @ 0.375 amps
20? ? ? ?27V? ? ? 100 W @ 0.5 amps
15? ? ? ?35V? ? ? ? 30 W? @ 0.25 amps
10-1? ?30V? ? ? ? ? 5 W? @ 0.2 amps
10-2? ?30V? ? ? ? ? 5 W? @ 0.2 amps
10-3? ?30V? ? ? ? ? 5 W? @ 0.2 amps
There may have been some de-tuning from the scope probe in
the circuit, I get about 25 W output on 10 without the probe
there.?
I have checked and double checked all the fingers on the band
switch.?
What should I look at next? Some component is out of spec
somewhere.
|
Re: TR-4C low power output on 15 & 10 meters
They are not new, but they test OK, about mid-way on the output scale. Is it not a valid way to test final tubes?
73, Dave
|
Re: Drake R4/T4 rubber feet machine screws
Steve and the group
those small rubber feet that screw into the bottom of the AC4 are in fact 6-32 thread. You can get the rubber feet from McMaster Carr, although I don¡¯t remember the part number off the top of my head
toggle quoted message
Show quoted text
On Feb 4, 2025, at 12:16 PM, Steve Wedge, W1ES/4 via < w1es@...> wrote:
Pretty sure it¡¯s 10-24.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 10:40 AM, Scott N1IA via?<soakland5@...> wrote:I am trying to get some machine screws for the rubber feet of the Drake R4 / T4. What size do I need??
Thanks guys, Scott N1IA
|
Re: The mysteriously modified 7077 (and nothing else¡)
I believe the latest manual, available at WB4HFN, shows the pinout for the two mic inputs.
Thanks, Evan. ?It is a TR7A, so perhaps I¡¯ll do some experimentation.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 10:09 AM, Evan via groups.io < k9sqg@...> wrote:
Yes for the TR-7A and possibly late production TR-7. ?One pin is for "high output high impedance" while the other is "low output low impedance"; ?basically just a resistor between the two pins. ?
Indeed.?
I thought I¡¯d heard that there are two audio inputs to the TR7. I¡¯m going to have to look at the service manual, as the owner¡¯s manual only shows pin 4 as n/c. Perhaps this low level element could directly feed the low-level input, if it exists¡
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 08:01, James Barrie via groups.io <
barrie43@...> wrote:
What a mess
Point taken. I haven¡¯t spent much on radio lately, so I owe it to myself :-D
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 20:47, Jim Shorney via
<
jimNU0C@...> wrote:
I hate to say it but you might be better off with the Heil cartridge. In my mic comparison runs, the 7077 cam in dead last behind various vintage Shure, Turner, E-V, and modified D-104/UGxx microphones for audio quality.
On Tue, 04 Feb 2025 01:36:40 +0000
"Steve Wedge, W1ES/4 via
" <w1es=
[email protected]> wrote:
> If I have to, I can install a Heil kit and know that I will have a good mic. But if I can regain the performance without spending another $70, I¡¯m good with that.
--
73
-Jim
NU0C
|
Re: TR-4C low power output on 15 & 10 meters
These are not new finals, correct? This appears to be finals that are at their end of life.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 11:12 AM, Dave KD5FX via groups.io < land.dave@...> wrote:
This is the same TR-4C that had the bad Xtals which were fixed by a baking. The problem now is the output is very low on 15 and 10 meters. Someone suggested I test the output on each band at the output of T9 which is on the driver. So I did and here is the results. Also, I re-tested the driver tube and the final, they all checked very good and I did a resistance test on the driver and finals as per the readings in the manual and they were all good.
Band? ?T9 out Power out
80? ? ? ?35V? ? ?130 W @ 0.4 amps
40? ? ? ?28V? ? ? ?90 W @ 0.375 amps
20? ? ? ?27V? ? ? 100 W @ 0.5 amps
15? ? ? ?35V? ? ? ? 30 W? @ 0.25 amps
10-1? ?30V? ? ? ? ? 5 W? @ 0.2 amps
10-2? ?30V? ? ? ? ? 5 W? @ 0.2 amps
10-3? ?30V? ? ? ? ? 5 W? @ 0.2 amps
There may have been some de-tuning from the scope probe in the circuit, I get about 25 W output on 10 without the probe there.?
I have checked and double checked all the fingers on the band switch.?
What should I look at next? Some component is out of spec somewhere.
|
Re: Drake R4/T4 rubber feet machine screws
Pretty sure it¡¯s 10-24.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 10:40 AM, Scott N1IA via groups.io < soakland5@...> wrote:
I am trying to get some machine screws for the rubber feet of the Drake R4 / T4. What size do I need?
Thanks guys,
Scott N1IA
|
Re: The mysteriously modified 7077 (and nothing else¡)
Thanks, Evan. ?It is a TR7A, so perhaps I¡¯ll do some experimentation.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 10:09 AM, Evan via groups.io < k9sqg@...> wrote:
Yes for the TR-7A and possibly late production TR-7. ?One pin is for "high output high impedance" while the other is "low output low impedance"; ?basically just a resistor between the two pins. ?
Indeed.?
I thought I¡¯d heard that there are two audio inputs to the TR7. I¡¯m going to have to look at the service manual, as the owner¡¯s manual only shows pin 4 as n/c. Perhaps this low level element could directly feed the low-level input, if it exists¡
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 4, 2025 at 08:01, James Barrie via groups.io <
barrie43@...> wrote:
What a mess
Point taken. I haven¡¯t spent much on radio lately, so I owe it to myself :-D
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 20:47, Jim Shorney via
<
jimNU0C@...> wrote:
I hate to say it but you might be better off with the Heil cartridge. In my mic comparison runs, the 7077 cam in dead last behind various vintage Shure, Turner, E-V, and modified D-104/UGxx microphones for audio quality.
On Tue, 04 Feb 2025 01:36:40 +0000
"Steve Wedge, W1ES/4 via
" <w1es=
[email protected]> wrote:
> If I have to, I can install a Heil kit and know that I will have a good mic. But if I can regain the performance without spending another $70, I¡¯m good with that.
--
73
-Jim
NU0C
|
Rob Sherwood
Jim Shorney
Marcus PY2PLL