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Re: Sorry to interrupt the silence....
Sorry I don't have one, but my Elmer W1LHY did in 1955. I wondered, how did it come to be? Aha, an engineer designed it! I will be an?engineer! And I did! First job out of school was National.? 73 Richard N1AA
Get
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... but I have a NC-125 and I am having trouble getting the Pitch Control (BFO) to work.
?
If anyone has one (NC125)? I'd ask you to pull the plastic knob & measure the resistance from chassis ground to the brass shaft and report here or email me at w8rmv at arrl dot net.
As I look at the construction, it looks like the brass shaft should be at or near ground level.
?
Coil L18 is supposed to be center tapped, but my 125's also has significantly more resistance on one side than the other.? Maybe I have a bad L18.
?
Still searching for an answer, as the rest of the NC125 works great!
?
73 - Bob W8RMV
?
?
?
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Sorry to interrupt the silence....
... but I have a NC-125 and I am having trouble getting the Pitch Control (BFO) to work.
?
If anyone has one (NC125)? I'd ask you to pull the plastic knob & measure the resistance from chassis ground to the brass shaft and report here or email me at w8rmv at arrl dot net.
As I look at the construction, it looks like the brass shaft should be at or near ground level.
?
Coil L18 is supposed to be center tapped, but my 125's also has significantly more resistance on one side than the other.? Maybe I have a bad L18.
?
Still searching for an answer, as the rest of the NC125 works great!
?
73 - Bob W8RMV
?
?
?
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Re: NCX-1000 update protective circuitry around 8122 or leave it stock?
The only thing I’ve done, in my case with my NCL-2000 amplifier which uses two 8122 tubes, is to install a series glitch resistor in the B+ line. ? By the way, 8122 tubes are plentiful as surplus, NOS or good used. They show up on eBay at least weekly. There’s no need to pay the $1200 or so from Burle. They were used by the thousands in civilian and military shipboard transmitters.
? One of my NCL-2000 amps had a blower failure when I got it. The tubes were blackened with heat. I replaced the blower, fired up the amp and believe it or not, the tubes still worked with full output.?
I’ve got about 16 spare 8122’s I purchased cheap from various sources, including a NOS matched pair for which I paid about $150. Yet, I’ve never had to use a spare. 73,
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On Jan 1, 2025, at 3:34 PM, John VE3PCN via groups.io <strupatjp77@...> wrote:
? Hi,
?
Anyone modified their NCX-1000 output section to better protect the expensive 8122 tube?
?
Several expert source provide direction how to extend the operating life of the tube and to reduce SSB distortion.
?
Example is the output section described here:
?
HF Circuits for a? Homebrew Transceiver?
By Mark Mandelkern, K5AM
?
QEX magazine NOV/DEC 2001
?
John VE3PCN
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NCX-1000 update protective circuitry around 8122 or leave it stock?
Hi,
?
Anyone modified their NCX-1000 output section to better protect the expensive 8122 tube?
?
Several expert source provide direction how to extend the operating life of the tube and to reduce SSB distortion.
?
Example is the output section described here:
?
HF Circuits for a? Homebrew Transceiver?
By Mark Mandelkern, K5AM
?
QEX magazine NOV/DEC 2001
?
John VE3PCN
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Re: National 1-10 Receiver
Can not figure out how to edit message so posting reply to my own message:? FOUND - no longer searching for these.
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I’m finally getting around to working with my SW-3 receiver (type 36 & 37) and it doesn’t use the normal 4 pin “plug & play” supplies. Looking at the schematic tells me there is 135v and 67v labeled B+ blue and green. There is the 6v filament on two leads with a 5th lead labeled yellow that appears to ground the 67v B+ voltage supply through some supply resistors. It’s labeled B- so I’m assuming it is connected to both negative B+ or is connected to the 135v high side if I’m using a dropping resistor to get my 67v.?
Does all this sound right or am I headed to a smoke escape event?
Thanks,
Tom N5AMA
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I just obtained a HRO-500 that is wired for 240v operation. It had been sold to and used by an European owner.
The manual describes a power terminal board and how to change the wiring for 120v operation.
However the wiring colors in my unit don’t match the wiring colors depicted in the manual. Obviously 4 of the wires must be for the dual transformer primaries.
There’s also other wires for the power input, and the switching.
Any thoughts as to how to trace this out?
Following the wiring thru the tightly laced wiring harness is a nightmare.
? Doug/WA1TUT?
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Hi all.? I'm just new to this particular group.? I'm finally getting through some of my 40+ year hoard and working on some receivers, and I've uncovered the National pile!? Among the hoard are some early HRO's (a Jr. and a Sr.) with a bunch of coil sets, a coil box and some speakers, and an old Navy R-116.
I also have a nice National 1-10 VHF receiver, which is the subject of this post and is coming to the top of my take-a-look-at-it list.? I'm looking for some help - this set used six coil sets to cover the entire frequency range (six sets of two coils each, labeled A1-A2, B1-B2, C1-C2, D1-D2, E1-E2, and F1-F2).? They are small, round coils enclosed in clear "plastic", about 1-5/16" diameter and 1-1/14" tall, each with 5 pins on the bottom.? I have the 'B' pair of coils, looking for the rest, or a full set.? Note that the ones I have are discolored, no longer clear but sort-of beige, probably from humid storage over the years and as shown in the photos attached.? Others out there might look like this too, but I'm not too concerned with appearance.? Attachments show the coil pair I have, a photo from the manual showing the coil sets, and a photo of my radio with a coil pair installed.
Anyone have any they can part with, or point to a possible source?? Any help appreciated - thank you!
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Hello All,
Looking for plug in set for HRO-60T. I have found 50T packs for sale, but nothing for a Sixty.? Can 50T coils be used in a sixty?
Thanks!
K5AKM?
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HRO-W Coil Packs Question
Coil packs come in bandspread and non-bandspread versions.? Can the bandspread coil packs be quickly tuned, in general, and then fine tuned using a bandspread function, or does their use restrict tuning to only very slow (although precise) bandspread tuning while inserted into the radio ?
73,
Bill
KJ5BNE
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Wanted: Dead Penta Labs 8122 tubes
Hi all,
I am looking for one or more dead Penta Labs 8122 tubes. Must be Penta Labs specifically.
Bob,? K7DYB
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Thanks Bob, I’ll check it out. 73, ?Doug/WA1TUT?
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On May 1, 2023, at 1:27 PM, Robert Kembel <rwkembel@...> wrote:
?Hi All,
Here is a writeup that I posted on the Hallicrafters forum that may be applicable here...
For several months, I have been trying to get the blower to start reliably at power on. Because the finals (8122) require cooling air, even during receive, I was so worried that I would damage the tubes due to lack of cooling resulting in overheating of the tube seals. In receive mode, a resistor in inserted in series with the blower motor to reduce the fan sped and thereby the noise. This resistor is shorted out when in transmit in order to increase the airflow while transmitting.
I took the blower assembly out and cleaned and lubed the motor multiple times, but to no avail. I had no luck finding a replacement blower, or even an original motor. I tried adding a resistor in parallel with the existing dropping resistor to raise the voltage during receive but the problem still persisted. Finally, I decided to try and fix the problem for once and for all.
Disclaimer: I don't know if the blower motor in my SR-2000 is original or not. I am somewhat suspicious because the motor seemed to be awfully close to the 6AQ5 audio output tube and adjacent relay.
On Amazon, I found a fairly universal replacement motor for a bath fan that looked like it would fit, so I ordered one to check it out. The listing specs were:
a.. Bathroom exhaust fan replacement: 50CFM, 0.65 amp, 3000 rpm, 120 volt, 60 Hz
b.. Shaft = 1.75" long x 3/16" diameter, wire length = 6" with 2-prong plug
c.. They have passed UL certified, stable and durable
d.. Mounting studs 1-7/8" on center
e.. Kit contains: 1 x motor, 1 x fan = 4.5 (flat/paddle style); Replacement for motors Nutone Broan, Uppco, Ventorola E498-1, Bay Motors, Sears 569, Dayton and many other units.
The size, mounting stud spacing and motor end cap size all looked like a good match. The only obvious problem was that my existing motor had a 1/4" shaft while this replacement has a 3/16" shaft.
The new motor arrived and I observed that the mounting studs projected from the wrong side of the motor (opposite the shaft). I unscrewed the studs and screwed them in from the opposite (back) side. The rear motor housing is threaded to accommodate the mounting studs so I needed to use nuts on the front side to hold the motor together. With the mounting studs now extending out the front (shaft) side of the motor, I could see that the motor would fit and the studs were long enough to mount the motor to the blower housing. I did need to add a washer between each of the mounting studs and blower housing so the motor winding bobbin cleared the blower housing, otherwise, the motor ended up being somewhat cocked. When the motor is mounted, the winding bobbin should face towards the PA cage.
With the motor in place, I was ready to tackle the shaft issue (motor shaft = 3/16" blower squirrel cage hole = 1/4"). I remembered that some Heathkit knobs used an insert to adapt the 1/4" knob hole to a 3/16" shaft and sure enough, that was just what was needed. The squirrel cage was positioned so that it cleared the opening cover plate, the set screws tightened, the AC plug on the end of the motor leads cut off (after confirming that the blower works ok), the blower reinstalled, and voila, everything now works fine. The new motor is not as deep as the one I replaced and there is now a reasonable amount of clearance between the motor and the 6AQ5 tube.
Hopefully, someone might find this information useful if they run into a similar problem.
Bob, K7DYB
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Hi All, Here is a writeup that I posted on the Hallicrafters forum that may be applicable here... For several months, I have been trying to get the blower to start reliably at power on. Because the finals (8122) require cooling air, even during receive, I was so worried that I would damage the tubes due to lack of cooling resulting in overheating of the tube seals. In receive mode, a resistor in inserted in series with the blower motor to reduce the fan sped and thereby the noise. This resistor is shorted out when in transmit in order to increase the airflow while transmitting. I took the blower assembly out and cleaned and lubed the motor multiple times, but to no avail. I had no luck finding a replacement blower, or even an original motor. I tried adding a resistor in parallel with the existing dropping resistor to raise the voltage during receive but the problem still persisted. Finally, I decided to try and fix the problem for once and for all. Disclaimer: I don't know if the blower motor in my SR-2000 is original or not. I am somewhat suspicious because the motor seemed to be awfully close to the 6AQ5 audio output tube and adjacent relay. On Amazon, I found a fairly universal replacement motor for a bath fan that looked like it would fit, so I ordered one to check it out. The listing specs were: a.. Bathroom exhaust fan replacement: 50CFM, 0.65 amp, 3000 rpm, 120 volt, 60 Hz b.. Shaft = 1.75" long x 3/16" diameter, wire length = 6" with 2-prong plug c.. They have passed UL certified, stable and durable d.. Mounting studs 1-7/8" on center e.. Kit contains: 1 x motor, 1 x fan = 4.5 (flat/paddle style); Replacement for motors Nutone Broan, Uppco, Ventorola E498-1, Bay Motors, Sears 569, Dayton and many other units. The size, mounting stud spacing and motor end cap size all looked like a good match. The only obvious problem was that my existing motor had a 1/4" shaft while this replacement has a 3/16" shaft. The new motor arrived and I observed that the mounting studs projected from the wrong side of the motor (opposite the shaft). I unscrewed the studs and screwed them in from the opposite (back) side. The rear motor housing is threaded to accommodate the mounting studs so I needed to use nuts on the front side to hold the motor together. With the mounting studs now extending out the front (shaft) side of the motor, I could see that the motor would fit and the studs were long enough to mount the motor to the blower housing. I did need to add a washer between each of the mounting studs and blower housing so the motor winding bobbin cleared the blower housing, otherwise, the motor ended up being somewhat cocked. When the motor is mounted, the winding bobbin should face towards the PA cage. With the motor in place, I was ready to tackle the shaft issue (motor shaft = 3/16" blower squirrel cage hole = 1/4"). I remembered that some Heathkit knobs used an insert to adapt the 1/4" knob hole to a 3/16" shaft and sure enough, that was just what was needed. The squirrel cage was positioned so that it cleared the opening cover plate, the set screws tightened, the AC plug on the end of the motor leads cut off (after confirming that the blower works ok), the blower reinstalled, and voila, everything now works fine. The new motor is not as deep as the one I replaced and there is now a reasonable amount of clearance between the motor and the 6AQ5 tube. Hopefully, someone might find this information useful if they run into a similar problem.  Bob, K7DYB
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Grainger should have shaft adapters to adapt one size to another. Donald KX8K On Mon, 01 May 2023 01:43:14 -0700, "Douglas L via groups.io" <sparks06524@...> wrote: Has anyone figured out a good substitute for the blower motor?
I’ve seen suggestions that Grainger might have one
but none in their catalog would seem to work.
I think the original motor shaft is 3/16” diameter. The Grainger motors of the approximate correct size are all 1/4” shafts. The problem would be fitting the blower wheel. I think it’s 2-3/4”diameter- not readily available.
Tnx,
Doug/WA1TUT
---------------------------------------------------- Some ham radio groups you may be interested in: /g/ICOM /g/Ham-Antennas/g/HamRadioHelp /g/Baofeng/g/CHIRP
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Has anyone figured out a good substitute for the blower motor?
I’ve seen suggestions that Grainger might have one
but none in their catalog would seem to work.
I think the original motor shaft is 3/16” diameter. The Grainger motors of the approximate correct size are all 1/4” shafts. The problem would be fitting the blower wheel. I think it’s 2-3/4”diameter- not readily available.
? Tnx,
?Doug/WA1TUT?
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Vintage National Speaker FS
Vintage National Speaker For Sale:
This speaker is a National speaker, with the
National logo on it. I think the model number
of the speaker is MCS-8. It looks very close to
the NC-46 TS but without the chrome base.
I have seen pictures of this speaker with HRO
receivers as well as other National receivers.
Actually, it would be a good match for most any
vintage receiver.
The speaker metal case measures 9 H x 10 W x 7-1/2 D
and weighs over 8 pounds. The weight gives you an
idea of the quality of the speaker magnet!
The actual speaker itself is labeled PM 8-9-5,
which I assume means it is an 8 inch permanent
magnet speaker.
The condition of this particular speaker is outstanding.
All four feet are present and are in great condition.
There may be a very tiny bit of dust.
Buy this terrific speaker for $135 plus shipping
from Florida.
I also have many other accessories available such as many
different types of microphones, HTs, VHF and UHF rigs, HF
and VHF/UHF antennas, connectors, miscellaneous accessories,
etc.
Just too many to list here. Please e-mail your requests.
.
Prices do not include shipping from Florida.
Thanks.
73,
Ken, W8EK
Ken Simpson
E-mail to W8EK@... or W8EK@...
Voice Phone (352) 732-8400
.
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Vintage National Speaker FS
Vintage National Speaker For Sale:
This speaker is a National speaker, with the
National logo on it. It apparently was made
to go with the NC-46 receiver, but I am sure
could be used with others as well. I think the
model number of the speaker is NC-46-TS.
It matches the NC-46 chrome base.
I have seen pictures of this speaker with HRO
receivers as well as other National receivers.
The case is lined with some sort of special
sound material, somewhat "waffle like" which
is still in extremely good shape.
The speaker metal case measures 9 H x 10-7/16 W
x 7-1/2 D and weighs about 8 pounds. The
weight gives you an idea of the quality!
The condition of this particular speaker is
outstanding. Pristine. I can not find a
defect of any sort. No scratches, dents,
or dings. Maybe a very tiny bit of dust.
All four feet are present and are in great
condition.
Buy this terrific speaker for $150 plus
shipping from Florida.
Thanks.
73,
Ken, W8EK
Ken Simpson
E-mail to W8EK@... or W8EK@...
Voice Phone (352) 732-8400
.
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Re: National NCL-2000 amp
Hello Jack, Thanks for your input.
I’ve got two NCL-2000’s.
For one I bought “Radio Dan’s” kit of an external keying box with a design similar to what you suggest. It works fine and presents a keying voltage of about 3 volts with just a few milliamps to the transceiver. For the other amp I simply installed in series with the relay a diode, current limiting resistor and a small filter cap. The keying voltage is now about 19 volts DC, although I’m sure with a lot of ripple. Nevertheless it seems to work fine with my Ten-Tec Jupiter which uses an open collector keying circuit.
73, Doug/WA1TUT?
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On Dec 13, 2022, at 9:39 AM, KO0T Jack Werthman via groups.io <jwerthman@...> wrote:
?Doug - I just saw this post and you may already have a solution. If not, then you could use a triac to switch the ac relay and a PNP transistor to switch the triac. The transistor would be turned on by pulling the base to negative through the open collector output of your transceiver. You would need to make a simple dc supply powered from the 13.8 vac supply in the amplifier. All of the new components could probably be mounted in the amplifier. Let me know if you want to pursue this.
Jack, KO?T?
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Re: National NCL-2000 amp
Doug - I just saw this post and you may already have a solution. If not, then you could use a triac to switch the ac relay and a PNP transistor to switch the triac. The transistor would be turned on by pulling the base to negative through the open collector output of your transceiver. You would need to make a simple dc supply powered from the 13.8 vac supply in the amplifier. All of the new components could probably be mounted in the amplifier. Let me know if you want to pursue this.
Jack, KO?T?
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Bob W8RMV
Robert Kembel
