Re: TR-4C Problems with 28.0 and 28.5 bands
No, there should be no shield on the driver. The shielding needed comes from the shield base. That is how Drake Engineers designed it.
How much power out do you get on 15?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 23, 2025 at 4:12 PM, Dave KD5FX via groups.io < land.dave@...> wrote:
Yes, using PTT after a tune. AND I swapped the 12BY7 with a spare I had on hand. I did notice the tube doesn't have a tube shield on it. Would that cause a problem like this?
Dave
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Re: T4XB with TC-6 Transmit Converter - remove the finals ?
No. The SC-6 switches the exciter¡¯s screen power off when in use. Besides putting in a place to connect screen connections to the final amp, you also need to add a connection for the 20m low-level signal that the SC-6 (or SC-2) uses.?
No holes need be drilled. There are SPARE holes already in the rear panel of the T-4XB.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 23, 2025 at 16:49, Gene Balinski K1NR via groups.io < g.balinski@...> wrote:
All,
?
? ? Could someone please remind me; do I need to remove the finals in the T4XB when using it to drive the TC-6? 6M transmit converter?? ?
?
? ? I know I have to do the screen voltage jumper thing, and I could not see any reference for final removal in the manual, but something in the back of my mind keeps telling me that the finals need to be pulled as well.? ?
?
? ? Could someone please confirm or deny ??
?
73 es thanks,
?
? ?Gene K1NR
|
On my L7 I noticed that the filliment choke had a slight bow in it. After further investigation I found that the core inside broken in two almost in the center. I think it's RFC2 on the schematic. It's right beside the Filliment transformer. Is this a bad thing? Do I need to replace the core? I don't know what to replace it with.
Thanks
Roger
KW4EMF
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Re: #ForSale Mill. spec. Relays for Sherwood boards
#ForSale
Please post photos. On Thu, 23 Jan 2025 08:36:04 -0800 "n2aug2 via groups.io" <n2aug2@...> wrote: For Sale I have Mill Spec HI G TO-5 relays the same ones Rob Sherwood used in the 80s & 90s on his filter boards very low loss spec for 1 million cycles they are NOS $20 for 2 shipped. my email good on QRZ. Thanks Richard/N2AUG -- 73 -Jim NU0C
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Re: TR-4C Problems with 28.0 and 28.5 bands
Yes, here it is, after RFC 13. 27 ohm. But
at the diagram notes 4. Highest Resistor Value seems R183. My copy
is not exactly clear :)
Em 23/01/2025 10:47, Steve Wedge,
W1ES/4 via groups.io escreveu:
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Yeah, I had a bit of a time trying to find R192
the first time or, actually, finding out the reference
designator was of ¡°that burnt resistor on the relay board¡±. ?The
schematic, if I remember, showed a lower number for highest ref.
des. used.
The resistor in question is on the relay board,
near the rear-centre. The resistor is right up near the top, so
it¡¯s easily replaced. ?It should be a 28 ohm, 1/2 watt. ?Most of
the MV for the set goes through that resistor, and I can¡¯t help
but think that Drake put it in there to be a fuse. ?That
resistor will save you if the cap fails shorted. ?I have
replaced some of the cans with discrete parts, so there is room
in there but using a Hayseed preserves all the wiring in place.
I reckon that going the Hayseed route is quite a bit more
expensive in Brazil.
I have seen some of these rigs with R192 replaced
by a 1W or even a 2W resistor! ?Those were not done by the
factory.
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 23, 2025 at 7:49 AM, Marcus PY2PLL <py2pll@...> wrote:
Hi Steve et al
Em 22/01/2025 22:35, Steve Wedge,
W1ES/4 via groups.io escreveu:
There are two relays. One controls changing
over the antenna and mute functions and the other, smaller
one changes enabling voltages from receive to transmit.
The schematic will show K1 and K2 relays.?
I read somewhere that there was 2 slightly different diagrams
for TR-4C, I mean above and below certain serial number. I never
found this "newer" diagram version (mine have serial 38636). On
it one relay is a quad one K1 (antenna, T/R cathodes grounding,
linear amp key) and K2 at the 9MHz oscillator (insert/short a
68pf cap to generate CW carrier).
Another note:!if this is a TR-4C of any type,
and it doesn¡¯t have a new can capacitor, plan on replacing
it either with a Hayseed replacement or by discrete parts.
The original can cap has a very high failure rate and
usually fails shorted ¡ª taking R192 with it. It¡¯s a good
thing that that resistor is there on the relay board, as it
saves the wiring from melting. If that resistor blows,
replace with the same value and rating to keep the
protection.?
This made me ask about this two diagrams. On the diagram I have
the highest resistor value is R183, highest cap C220. The quad
one at this schematic is C145. Still the original here, I'll
measure-it one of this days but I'll "build" a new can with
newer parts ?. But inspecting the diagram R192 seems to be
there, near the power supply connector. Image not clear.
73 Marcus PY2PLL
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Re: TR-4C Problems with 28.0 and 28.5 bands
At this point (28 and 28.5 oscillators
recovered) had you readjusted the RX/TX IF chains and preselector
stages according to the user manual instructions? When mine
arrived a couple of months ago this was my 1st procedure: peak
again all tuned circuits according to the manual instructions.
I noticed small differences on RX side (by ear I mean) but large
difference on TX: at 15m power jumped from ~80W to - 145W CW
(measures ~165W PEP when talking, power supply with more room).
Later I modified two things on mine: I converted the 2 RCAs at the
rear to sort of RX antenna loop. I don't want to use any external
receiver, I brought this TR-4C/VF-4C to use it as is. There I
insert sometimes an external RF pre amp to improve RX on higher
bands or an old JPS ANC4 Antenna Noise Canceller, to help me get
rid of electric noise on lower bands.
This mod revealed me a "characteristic" of TR4 (that later I found
mentions at a couple of comments in old forums): after you peak
10m preselector tracking per manual instructions, TX peak
does not occur at the same point on 10m.
I observed that RX was ok but TX reaches only 65W CW. But if I peak
the preselector per max power, I reach 90W but RX became a bit deaf.
RX peak at 12 o'clock, TX peak at 1:30M lol.
Then once with the RX antenna loop unplugged, I noticed that not
only the RX max noise matched the TX max power point (let's 12
o'clock on 28.5) but also the TX power has raised to ~110W CW (peaks
140 PEP when talking). As soon I restored the RX antenna connection,
this peak position displaced again.
Seems that the open coaxial cable capacitance between K1 area and T9
was playing some role. I even replaced this cable by a fresh RG174
with the same results. But it's OK if I keep it open the loop at the
RCAs jacks.
My solution: I rectified 12V filament, stabilized with a 7805 and
installed a 5V Omron?SMD at one RCA jack. Its command came from pins
5 and 8 of the power supply connector. On RX, coax is connected to
K1. On TX, coax is "unplugged". May be better if I placed this relay
(K3 now hihi) right after T9. But it's working this way and my eyes
are not the same.
73 Marcus PY2PLL
Em 23/01/2025 18:41, Dave KD5FX via
groups.io escreveu:
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Show quoted text
Another symptom, when I key up on the high bands after tuning
up the plate current maxes out! Like it's in self oscillation or
something.
Dave
|
Re: T4XB with TC-6 Transmit Converter - remove the finals ?
|
Re: T4XB with TC-6 Transmit Converter - remove the finals ?
I did not remove the finals when I ran mine. Ed KG5UN
On Thu, Jan 23, 2025 at 3:49?PM Gene Balinski K1NR via <g.balinski= [email protected]> wrote: All,
?
? ? Could someone please remind me; do I need to remove the finals in the T4XB when using it to drive the TC-6? 6M transmit converter?? ?
?
? ? I know I have to do the screen voltage jumper thing, and I could not see any reference for final removal in the manual, but something in the back of my mind keeps telling me that the finals need to be pulled as well.? ?
?
? ? Could someone please confirm or deny ??
?
73 es thanks,
?
? ?Gene K1NR
|
T4XB with TC-6 Transmit Converter - remove the finals ?
All,
?
? ? Could someone please remind me; do I need to remove the finals in the T4XB when using it to drive the TC-6? 6M transmit converter?? ?
?
? ? I know I have to do the screen voltage jumper thing, and I could not see any reference for final removal in the manual, but something in the back of my mind keeps telling me that the finals need to be pulled as well.? ?
?
? ? Could someone please confirm or deny ??
?
73 es thanks,
?
? ?Gene K1NR
|
Re: TR-4C Problems with 28.0 and 28.5 bands
Another symptom, when I key up on the high bands after tuning up the plate current maxes out! Like it's in self oscillation or something.
Dave
|
Re: TR-4C Problems with 28.0 and 28.5 bands
Drake used the bottom only of tube shields on some tubes. Makes it look like the shield is missing but its not. The lower part of the shield provides adequate shielding to the leads to the socket without causing the tubes to run hot.
toggle quoted message
Show quoted text
On 1/23/2025 1:12 PM, Dave KD5FX via groups.io wrote: Yes, using PTT after a tune. AND I swapped the 12BY7 with a spare I had on hand. I did notice the tube doesn't have a tube shield on it. Would that cause a problem like this?
Dave
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: TR-4C Problems with 28.0 and 28.5 bands
Yes, using PTT after a tune. AND I swapped the 12BY7 with a spare I had on hand. I did notice the tube doesn't have a tube shield on it. Would that cause a problem like this?
Dave
|
Thanks very much for all your reply's.
Tim
WB8UHZ
On Thursday, January 23, 2025 at 10:52:34 AM EST, Clint VE3CMQ <ve6cmm@...> wrote:
I don't think you would have any problem with making the swap.? If all the filaments are in series, the 2 volt difference would be spread over the entire string.? The thing to check would be the filament current between the two as they could be significantly different.
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Jim Shorney via groups.io Sent: Wednesday, 22 January 2025 21:20 To: [email protected]Subject: Re: [DRAKE-RADIO] 6BN8/8BN8 I suppose that the 8BN8 would more likely be found in the television repair man's caddy. There are quite a few on eBay right now. On Wed, 22 Jan 2025 20:59:29 -0600 "Gary Follett via groups.io" <xntrick1948@...> wrote: > I have half a dozen of 6BN8 tubes and zero 8BN8 tubes. -- 73 -Jim NU0C
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Re: TR-4C Problems with 28.0 and 28.5 bands
Is this in PTT?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 23, 2025 at 10:27, Dave KD5FX via groups.io < land.dave@...> wrote:
Well, this morning it's behaving normally and I was able to set the BIAS with no problems. Strange! I'm hearing lots of stations on 28.0 and 28.5 bands this morning but nothing yet on 29.1. I can hear my signal generator up there so I know it's working, that part of the band just isn't open yet or there's nobody up there. The can cap (C145?) has been replaced with individual caps by a previous owner.
Current problem is Xmit on 21/28/28.5/29.1 bands. It will tune up but when I key up the mic I don't get an SSB output. It's a strange output, it will send a very brief output on loud voice peaks but nothing on lower volumes. This is with the Xmtr gain all the way up and a hand mic that works just fine on 80/40/20. What output I do get when tuning up is about half of what I get on the lower bands.
73, Dave
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Re: TR4310 HF Transceiver
Mark:
I have four of those knobs, although they do not have the white dot.? You'd have to add that yourself.? Shouldn't be too hard to do with a small?drill bit in a drill press, and add some white acrylic paint.? I'd be happy to send you one knob.
73 Peter VE7PS
Gregory,
?
I believe this type to be that which I need for the mode switch on the TR4310. Seems it's no longer listed on the EHC website though.
?
?
The data I found on it here:
says, 'Two 4-40 UNC set screws'. I'm guessing that the set screws require a very small, imperial ('freedom unit', in the US - HI!), hex-type wrench. I have one that I reckon is the correct size and that I've used on knobs for Atlas radio, but darned if I can find it right now!
?
Regards,
?
Mark, G4FPH.
?
|
#ForSale Mill. spec. Relays for Sherwood boards
#ForSale
For Sale I have Mill Spec HI G TO-5 relays the same ones Rob Sherwood used in the 80s & 90s on his filter boards very low loss spec for 1 million cycles they are NOS $20 for 2 shipped. my email good on QRZ. Thanks Richard/N2AUG?
|
I don't think you would have any problem with making the swap. If all the filaments are in series, the 2 volt difference would be spread over the entire string. The thing to check would be the filament current between the two as they could be significantly different.
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Jim Shorney via groups.io Sent: Wednesday, 22 January 2025 21:20 To: [email protected]Subject: Re: [DRAKE-RADIO] 6BN8/8BN8 I suppose that the 8BN8 would more likely be found in the television repair man's caddy. There are quite a few on eBay right now. On Wed, 22 Jan 2025 20:59:29 -0600 "Gary Follett via groups.io" <xntrick1948@...> wrote: I have half a dozen of 6BN8 tubes and zero 8BN8 tubes. -- 73 -Jim NU0C
|
Re: TR-4C Problems with 28.0 and 28.5 bands
Have you swapped the 12BY7 driver tube?? I had a problem with erratic bias and an oscillation on higher bands in a TR-3 recently that was resolved with a swap of the driver tube.? The tube tested good on my basic tube tester.
|
Re: TR-4C Problems with 28.0 and 28.5 bands
Well, this morning it's behaving normally and I was able to set the BIAS with no problems. Strange! I'm hearing lots of stations on 28.0 and 28.5 bands this morning but nothing yet on 29.1. I can hear my signal generator up there so I know it's working, that part of the band just isn't open yet or there's nobody up there. The can cap (C145?) has been replaced with individual caps by a previous owner.
Current problem is Xmit on 21/28/28.5/29.1 bands. It will tune up but when I key up the mic I don't get an SSB output. It's a strange output, it will send a very brief output on loud voice peaks but nothing on lower volumes. This is with the Xmtr gain all the way up and a hand mic that works just fine on 80/40/20. What output I do get when tuning up is about half of what I get on the lower bands.
73, Dave
|
Re: TR4310 HF Transceiver
Good to hear from another TR4310 user, Jan:-) I reckon I have both sizes of those key here - somewhere!
?
?
With the synthesiser in the TR4310 now working well (and the VCXO / rubber-crystal alignment for the 100s & 10s Hz tuning steps complete), this morning, I turned my attention to finding the reason the radio would often refuse to tune in one direction.
?
My workaround to this problem while de-bugging the synthesiser was to remove U32002, the up/down direction setting flip-flop on the VRTO Digital Board, tie TP-5 (normally the output of the flip-flop) high with a resistor and also connect TP-5 to a push-button, the other side of which was connected to ground. The pull-up meant that the radio would normally tune up the band. Pushing and holding the button would allow it to tune down. Hardly a slick user interface, but adequate for getting around!
?
I had previously installed a DIL socket in the U32002 position, which had the benefit of being able to easily insert and remove the required IC (CMOS MC14027 / 4027 type) to aid testing. Plugging the IC back in and removing my temporary pull-up / button circuitry, the erratic tuning was still present. Tuning down the band / from high to low frequency was reliable. Attempting to tune up the band / from low to high frequency would work occasionally, but then get stuck at positions where no further low to high tuning could be made. The alignment section of the manual talks about adjusting the (movable) opto switch to optimise accuracy of tuning direction sensing decisions. While in the bowels of the radio sorting the synthesiser, I had previously taken a detour to check and adjust the opto switch mechanical position. Once again, using a dual-channel 'scope, I checked the squared up outputs from the opto switches at TP-3 and TP4. Their output signals were as close to being in quadrature (90-degrees) with one another as I thought was ever likely to be needed.
?
Attempting to tune around some more on the 'VFO', I noticed that the frequency readout (still only reliable for 10s & 1s kHz and 100 Hz digits) would appear to get stuck at various 'round number' values. This suggested that the circuitry thought that the radio was reaching it's upper frequency tuning limit, without actually being there. The TR4310 incorporates circuitry to detect the lower and upper limit of the, nominally 500 kHz, tuning range. (Actually, the radio will allow you to tune up to 200 kHz below the nominal 500 kHz range and up to 50 kHz above - these are the detected 'hard' limits.)
?
Checking the 'R' pin (12) on the flip-flop with a 'scope, I could see no 'high' input that corresponded to upper limit reached, and no pulses when tuning. The logic level looked to be a good '0'. Then I noticed that, with the 'scope probe attached, the radio was perfectly happy to tune low to high in frequency. Remove the 'scope probe and it would readily get stuck again! So, there really were pulses / logic '1's there, but with so little current behind them that the slightest load (and we're talking very slight from a scope probe) was enough to reduce them to zero Volt / make them ineffective.
?
?
Pin 12 on the direction setting flip-flop is driven directly from the output of another IC on the board, U32009(A), a quad-input NAND (CMOS MC14082 / 4082). A search of my parts draw yielded a Philips HEF4082, near enough for jazz. After the now somewhat tiresome removal of the faulty IC, cleaning the board to remove traces of brown 'mud', and installation of an IC socket, I plugged-in the new IC and re-installed the board in the radio. Success! The radio now tuned in both directions freely and reliably. I've not yet checked that the tuning limit checking circuitry is getting its calculations right - it's somewhat hard to do when the 100s kHz digit is broken - but this can wait.
?
?
On the subject of said digit, doing some further poking about, the cause of this fault would appear to be the BCD adder IC, interspersed between the 100s kHz BCD counter outputs and the seven-segment display driver inputs, to ensure the display digit reads correctly regardless of whether a range starting at 0 kHz, or 500 kHz above the MHz edge is selected. Once again, a UK eBay seller happened to be selling lots of two IC (type MC14560) for little money - should be here in a day, or two.
?
Looking ahead to when the 100 kHz digit issue is fixed, that will leave only one faulty area to go - that of the MHz display digits and range selection from the band switch, including the up/down buttons. The MHz display digits are currently mostly blank, or just plain wrong and the up/down buttons inoperable. I've been able to make contacts on the radio by virtue of the installed AUX7 card which, in addition to the usual modules for LW and MW BC, fortunately also has modules for 80 - 10 metre pre-WARC amateur bands. Standby for further tails of brown mud, failed CMOS and the rest!
?
Regards, G4FPH.
?
?
|
Jim Shorney
Marcus PY2PLL
Ed KG5UN