Soldering an Anode HV Cap-Contact Back In Place; Solder Alloy Used?
I¡¯m looking for anyone¡¯s experience in successfully soldering an anode high voltage cap-contact on a final tube. ?Particularly, being that the typical maximum bulb temperature of the tube is 500 degrees F, most commonly available modern solder alloys have a melting temperature around 430 degrees F, that is the non-leaded alloys; I expect adding lead would decrease the melting temperature further. ?Industry defines a 96.5% Sn - 3% Ag - ?0.5 % Cu alloy as ¡°High Temperature Solder.¡± ?With the anode in direct contact with the bulb sitting centrally just above the heater, and heat rising, I would expect this solder would melt during normal operation due to the heat being constantly added. ?The tube manufacturers used some kind of solder to electrically bond the anode wire that penetrates the glass bulb to the HV cap-contact: what alloy, I know not. ?What has been your experience in re-soldering the anode HV contact on these final tubes? ?Successful to date?
?
Thank you.
?
73, Michael Smith, N4KZO
|
Re: OT: D'Arsonval Meter Repair
How about low-temperature solder paste? Then hit it with a hot air
rework gun with the smallest tip.
- Jerry, KF6VB
toggle quoted message
Show quoted text
On 2025-01-30 12:37, n4buq wrote: Sorry for the OT but I don't have a lot of options. I've searched
this out and haven't found a whole lot on the subject.
I have a taut band meter that was damaged during transit. The "hub"
that attaches the rear band to the coil form became unattached to the
coil form and, as a result, the fine wire that connected the rear hub
to the coil is broken.
I can CA glue the hub to the coil form but I'm not sure if/how I can
re-solder the wire to the hub's solder tab but I'm not sure how to
regain access to the wire. I can see where they brought the wire up
and about half-way around the hub and that part of the wire is still
there but it is encapsulated in whatever was used to seal the coil.
Anyone know what was typically used as a sealant/affixer? I'm
thinking it is either varnish or shellac but could be something else.
I think if I could dissolve that small area and free up a tiny length
of that wire, I might a half-chance of soldering to it. Anyone know?
Thanks,
Barry - N4BUQ
|
Donnie, testing today with an R-4, which has only one 6HS6 -- the pre-mixer.
?
I tested 5 tubes in the socket: 6HS6, 6AH6, 6AU6, 6BA6, and the Russian 6J5P. There was no difference in the AGC set point using any of the tubes -- the bias was stable (with no antenna connected and RF gain fully CW).
?
On 40m, the calibrator was about 10dB over 9 with the HS6, 5dB over with all others except the BA6. The 6BA6 was about S8.
?
So in summary, perhaps a 5dB or so loss in gain using any other tube than the 6HS6 as the pre-mixer. As noted previously, there was no difference in signal strength with 6AH6/6J5P as the first mixer instead of 6HS6 in another receiver.
?
Dave
|
OT: D'Arsonval Meter Repair
Sorry for the OT but I don't have a lot of options. I've searched this out and haven't found a whole lot on the subject.
I have a taut band meter that was damaged during transit. The "hub" that attaches the rear band to the coil form became unattached to the coil form and, as a result, the fine wire that connected the rear hub to the coil is broken.
I can CA glue the hub to the coil form but I'm not sure if/how I can re-solder the wire to the hub's solder tab but I'm not sure how to regain access to the wire. I can see where they brought the wire up and about half-way around the hub and that part of the wire is still there but it is encapsulated in whatever was used to seal the coil.
Anyone know what was typically used as a sealant/affixer? I'm thinking it is either varnish or shellac but could be something else. I think if I could dissolve that small area and free up a tiny length of that wire, I might a half-chance of soldering to it. Anyone know?
Thanks,
Barry - N4BUQ
|
Re: R-4C Filter Insertion Loss?
Thanks Steve. After swapping them into different positions on the back, the attenuation follows the filter.?
?
I did not realize that you can still buy these filters! Fortunately I have the GUF-1 installed so the 500Hz filter is more than enough with PB & Notch.?
--
Craig/W8CS
Greenville, SC
|
I will check on that, too. These are used as mixers, so overall gain shouldn¡¯t be as big an issue but yes, it¡¯s important to have the bias at -1.35V before starting.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 30, 2025 at 13:12, Ralph Mowery via groups.io < ku4pt@...> wrote:
In addition to all that which is good, the circuits around the tubes may need to be adjusted when the tubes are changed.
Ralph ku4pt
On Thursday, January 30, 2025 at 12:27:54 PM EST, DONNIE WA9TGT via groups.io <cfzepp@...> wrote:
When you do your test you first need to make sure the resting AGC bias voltage is properly set (Rcvr Sensitivity) then set s-meter to 1 ?Then make your test.?
?
Then after substituting the 6AH6 tube for the 6HS6 you need to recheck the resting AGC voltage again because as it may need re-adjusting as well as the s-meter reset to 1. Otherwise it will not be a fair test.?
Donnie / WA9TGT
_.__,_
|
Re: R-4C Filter Insertion Loss?
There should not be an appreciable difference amongst the various filters. Sometimes, maybe half an S unit on the 250 but most should be the same ¡ª when peaked on a single-frequency signal (like the calibrator).?
It is easiest to find another 250 filter but you may be able to repair it with a significant amount of work on your part.?
I bought a TR-4Cw RIT a few years ago and was crestfallen when tie narrow filter had about 25 dB of loss. I took the filter apart and found the bad crystal (one of the 6 in there). I was fortunate enough to fix it by baking it in a 350¡ãF oven.?
With the TR-4 filter, I really had no choice because those don¡¯t grow on trees. R-4C filters are plentiful and you can even buy new ones from Noble.?
BTW, it was probably 4-6 hours to find the bad one and correct the problem.?
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 30, 2025 at 12:09, Craig W8CS via groups.io < craig_severson@...> wrote:
Jeff-
?
I'm running a 29MHz test signal directly into the antenna jack as a reference. I don't know the amplitude of the signal but probably <1.0 microvolt.??
SSB filter - S8 on the meter
1.5KHz filter - S4.5
500 Hz filter - S8
250 Hz filter - does not move the S meter, audible above noise floor but significantly quieter.?
--
Craig/W8CS
Greenville, SC
|
In addition to all that which is good, the circuits around the tubes may need to be adjusted when the tubes are changed.
Ralph ku4pt
On Thursday, January 30, 2025 at 12:27:54 PM EST, DONNIE WA9TGT via groups.io <cfzepp@...> wrote:
When you do your test you first need to make sure the resting AGC bias voltage is properly set (Rcvr Sensitivity) then set s-meter to 1 ?Then make your test.?
?
Then after substituting the 6AH6 tube for the 6HS6 you need to recheck the resting AGC voltage again because as it may need re-adjusting as well as the s-meter reset to 1. Otherwise it will not be a fair test.?
Donnie / WA9TGT
_.__,_
|
I will do so. ?I have an R-4B that¡¯s coming to my bench soon and it will be a good opportunity. ?I don¡¯t have any of the Russian tubes but just for the heck of it, I¡¯ll also test with the 6AU6. ?I expect the gain of the latter to be low and it may not be useable. ?But I will know.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 30, 2025 at 12:27 PM, DONNIE WA9TGT via groups.io < cfzepp@...> wrote:
When you do your test you first need to make sure the resting AGC bias voltage is properly set (Rcvr Sensitivity) then set s-meter to 1 ?Then make your test.?
?
Then after substituting the 6AH6 tube for the 6HS6 you need to recheck the resting AGC voltage again because as it may need re-adjusting as well as the s-meter reset to 1. Otherwise it will not be a fair test.?
Donnie / WA9TGT
|
Re: R-4C Filter Insertion Loss?
OK, hard to say but that is quite the change in amplitude.? There
are other variables as the other guys have mentioned but the 250
hz drop out specifically is definitely indicating some kind of a
problem which could be the filter or something in the switching
chain.
73/jeff/ac0c
alpha-charlie-zero-charlie
On 1/30/2025 11:09 AM, Craig W8CS via
groups.io wrote:
toggle quoted message
Show quoted text
Jeff-
?
I'm running a 29MHz test signal directly into the antenna
jack as a reference. I don't know the amplitude of the signal
but probably <1.0 microvolt.??
SSB filter - S8 on the meter
1.5KHz filter - S4.5
500 Hz filter - S8
250 Hz filter - does not move the S meter, audible above
noise floor but significantly quieter.?
--
Craig/W8CS
Greenville, SC
|
When you do your test you first need to make sure the resting AGC bias voltage is properly set (Rcvr Sensitivity) then set s-meter to 1 ?Then make your test.?
?
Then after substituting the 6AH6 tube for the 6HS6 you need to recheck the resting AGC voltage again because as it may need re-adjusting as well as the s-meter reset to 1. Otherwise it will not be a fair test.?
Donnie / WA9TGT
|
Re: R-4C Filter Insertion Loss?
Jeff-
?
I'm running a 29MHz test signal directly into the antenna jack as a reference. I don't know the amplitude of the signal but probably <1.0 microvolt.??
SSB filter - S8 on the meter
1.5KHz filter - S4.5
500 Hz filter - S8
250 Hz filter - does not move the S meter, audible above noise floor but significantly quieter.?
--
Craig/W8CS
Greenville, SC
|
Re: R-4C Filter Insertion Loss?
Craig,
Can you quantify what "huge" means in your observation?
73/jeff/ac0c
alpha-charlie-zero-charlie
On 1/30/2025 10:26 AM, Craig W8CS via
groups.io wrote:
toggle quoted message
Show quoted text
Is it normal to see a big insertion loss with the Network
Sciences filters? I see a huge insertion loss with the 250Hz
filter, and also somewhat degraded with the 1500Hz filter. These
date 76/77 so not sure if they accumulate loss with age.
Fortunately I mostly use 500/SSB filters, but the loss renders
especially the 250Hz filter to be almost useless.?
?
I've swapped them with the 500Hz socket and the loss follows
the filter itself.?
?
Just curious if y'all have seen something similar. Thanks
--
Craig/W8CS
Greenville, SC
|
Re: R-4C Filter Insertion Loss?
Not being an expert, I too noticed this with C lines I owned years ago. ? Part of the issue is due to a receiver that was not properly aligned. ? That's not to say a filter hasn't "drifted" but a sweep generator could help resolve that. Let's hear what the experts say...
Is it normal to see a big insertion loss with the Network Sciences filters? I see a huge insertion loss with the 250Hz filter, and also somewhat degraded with the 1500Hz filter. These date 76/77 so not sure if they accumulate loss with age. Fortunately I mostly use 500/SSB filters, but the loss renders especially the 250Hz filter to be almost useless.?
?
I've swapped them with the 500Hz socket and the loss follows the filter itself.?
?
Just curious if y'all have seen something similar. Thanks
--
Craig/W8CS
Greenville, SC
|
R-4C Filter Insertion Loss?
Is it normal to see a big insertion loss with the Network Sciences filters? I see a huge insertion loss with the 250Hz filter, and also somewhat degraded with the 1500Hz filter. These date 76/77 so not sure if they accumulate loss with age. Fortunately I mostly use 500/SSB filters, but the loss renders especially the 250Hz filter to be almost useless.?
?
I've swapped them with the 500Hz socket and the loss follows the filter itself.?
?
Just curious if y'all have seen something similar. Thanks
--
Craig/W8CS
Greenville, SC
|
I finally found the problem with no transmitter?output. The MC1496 Balanced Modulator/Demodulator I.C. was bad. I assume?whatever took out the 2N4427 buffer amplifier transistor also damaged the I.C. Receiver mixer does not seem to be damaged so just wondering if it was the 10 volt transmit voltage. Just waiting for a replacement I.C. Will let you know how I make out when I get that part.
Jim VE1RB
|
Re: TR-4C Problems with 28.0 and 28.5 bands
This is a very long thread¡ have you already replaced the can cap? ?If not, you need to before powering up again. The blown 27 ohm resistor acted as a fuse and protected your wiring.?
Be sure to replace with the same-rating parts! ?The 27-ohm blowing was a good thing¡
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 30, 2025 at 09:34, Dave KD5FX via groups.io < land.dave@...> wrote:
UPDATE! WOW! I got a PM that directed me to check the 2 ohm resistor on the board by the relay and that was FRIED! Along with the 27 ohm resistor below it. They both were cracked in half which I proved by poking them with a screwdriver. So now I'm waiting on some replacements and then I'll reset the BIAS and see how it operates.
?
|
Re: TR-4C Problems with 28.0 and 28.5 bands
UPDATE! WOW! I got a PM that directed me to check the 2 ohm resistor on the board by the relay and that was FRIED! Along with the 27 ohm resistor below it. They both were cracked in half which I proved by poking them with a screwdriver. So now I'm waiting on some replacements and then I'll reset the BIAS and see how it operates.
?
|
I may need to do this for the 6AH6 vs 6HS6. I have a decent signal generator now, so at least single-signal can be evaluated.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Wed, Jan 29, 2025 at 20:49, Jim Shorney via groups.io < jimNU0C@...> wrote:
The next question would be how do they impact weak signal performance and AGC action?
On Wed, 29 Jan 2025 14:35:42 -0800
"Dave W7GZ via groups.io" <w7gz@...> wrote:
> using the calibrator on 40m as my test signal, I noticed no difference among the meter readings using any of the 3 types
--
73
-Jim
NU0C
|
Re: Cleaning/degreasing Chemicals?? ?
On 2025-01-29 19:59, Richard Knoppow via groups.io wrote: The most sensitive transformers and chokes were sealed units because
the seals could let in a small amount of moisture which then had
difficulty getting out again. *** Yes! That was the sort of transformer my dear departed DX40 had. In a can, sealed with tar or something. If it had been an open-frame transformer, I would have taken it apart and rewound it. - Jerry, KF6VB
|
Craig W8CS
DONNIE WA9TGT
