Metalwork - Lathe and Mill topics: 2026

Thursday, 16 July 2026

Re: [Amateur-repairs] Test Equipment Question

May I safely presume your new system relies on present "equipment" in ones home hobby shop? (your comment " depending on how much ancillary equipment you might already have."

How does your system depend of the accuracy and repeatability of those existing equipment?

As a retired developer, I have an extensive collection of electronic test equipment...some quite expensive for it's day, but all out of calibration and likely specifications.

What does your new system bring the hobbyist that a $200 China built LCR doesn't?

Terry WA7LGY

On 7/15/2026 2:03 PM, K8BYP via groups.io wrote:

Since the Users here are more 'hands on...'

I have developed a very low cost L-C-R test system that can measure

down to 5 decimal place resolution and about 0.1 % accuracy.

AT RF FREQUENCY

Commercial units are on the order of $5,000 - 20,000 USD for a few MHz test frequency.

My system should be able to go VHF, but I haven't verified that.

Is this of any use to the Amateur world?

Cost "guess," $200 - 2000 USD, depending on how much ancillary equipment you might already have.

Dave K8BYP

Re: [Amateur-repairs] Test Equipment Question

"Chimichanga..." 🤣🤣🤣🤣🤣🤣. Whats really annoying about "that" equipment, the new omron etc cookie cutter digital boxes, is that they have high end features, hidden in SW. If one only had the unlock codes!

Re equipment, nice assortment, good engineering economy. Yes, agreed as to class of buyer; you self identify as an engineer, the vast majority of 'us' today have no clue what that equipment is for.

Id likely not go for $2000 either, since I have little need for this. But for what need theres been, nothing can replace it.

The $20,000 USD, 8 MHz LCR box cant find self resonances at 41 MHz...( Why doesnt my new circuit work???)

On Thursday, July 16, 2026, Kirk Kleinschmidt NT0Z via groups.io <sohosources=yahoo.com@groups.io> wrote:

OP: As a hobby ham engineer: At $200? You bet. At $2000? Never. :) Well, unless I win the lottery. My LCR is a DE-5000 (bought for $110, now about $200). I have scopes and a spectrum analyzer that a very generous Santa gave me in 2014. I have a GPS-disciplined counter from 1975. I have a Chimichanga-brand signal gen, plus some vintage signal generators for fun. I have a couple late '70s HP benchtop DMMs that still spec well.

For my "class" of potential buyer I think I'm fairly typical. Although your instrument sounds fantastic, I don't see myself paying more than $200 for one, as my needs and finances probably don't support it.

So, here's my vote for the $200 price point! :)

Regards,

Kirk, NT0Z

Rochester, MN

My book, "Stealth Amateur Radio," is now available from www.stealthamateur.com and on the Amazon Kindle (soon)

On Wednesday, July 15, 2026 at 05:14:03 PM CDT, K8BYP via groups.io <davecbyp=gmail.com@groups.io> wrote:

Very good insider info. Such is used in quartz crystal manufacturing for production testing but such co's wouldnt want my approximation of test eq, they have money for real equipment.
A TW XTAL house sent me a prototype crystal run with QA data to 6 d.p., so thats beat my meager attempt by quite a bit. That was SSB filter XTALS for the Drake TR rigs.

Such gear is so far beyond most Amateur uses I cant imagine who'd want it. Ive used it to exactly verify network calculations and components, but how often is that done?

An inexpensive Nano could be used for general testing but a VNA isnt really suitable for that, it expects a characteristic R-50 termination.

Most of my testing is with a B&K 5.5 digit DMM to measure a capacitor, and resonant circuit with an AWG and MW diode probe (10 USD), to calculate inductor values. But thats $1000 USD in gear.

The B&K handheld LCR Meters are now up to 500 USD, but not great for RF use.

????

On Wednesday, July 15, 2026, David VK2CZ via groups.io <16240244c1=gmail.com@groups.io> wrote:

Hello Dave,

Your development sounds very interesting. Having spent 10 years of my career in manufacturing a significant amount of RF systems with NEC and Ericsson, component validation was only sampled using frequencies up to 5kHz.. we relied heavy on manufacturer QA.

If was to assess say a resistor at say 50Mhz, I'd probably use a component jig with a network analyzer.. then of course using kelvin clips become useless..

That said, still thinking of possible applications.

David VK2CZ

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Re: [Amateur-repairs] Test Equipment Question

OP: As a hobby ham engineer: At $200? You bet. At $2000? Never. :) Well, unless I win the lottery. My LCR is a DE-5000 (bought for $110, now about $200). I have scopes and a spectrum analyzer that a very generous Santa gave me in 2014. I have a GPS-disciplined counter from 1975. I have a Chimichanga-brand signal gen, plus some vintage signal generators for fun. I have a couple late '70s HP benchtop DMMs that still spec well.

For my "class" of potential buyer I think I'm fairly typical. Although your instrument sounds fantastic, I don't see myself paying more than $200 for one, as my needs and finances probably don't support it.

So, here's my vote for the $200 price point! :)

Regards,

Kirk, NT0Z

Rochester, MN

My book, "Stealth Amateur Radio," is now available from www.stealthamateur.com and on the Amazon Kindle (soon)

On Wednesday, July 15, 2026 at 05:14:03 PM CDT, K8BYP via groups.io <davecbyp=gmail.com@groups.io> wrote:

Very good insider info. Such is used in quartz crystal manufacturing for production testing but such co's wouldnt want my approximation of test eq, they have money for real equipment.

A TW XTAL house sent me a prototype crystal run with QA data to 6 d.p., so thats beat my meager attempt by quite a bit. That was SSB filter XTALS for the Drake TR rigs.

Such gear is so far beyond most Amateur uses I cant imagine who'd want it. Ive used it to exactly verify network calculations and components, but how often is that done?

An inexpensive Nano could be used for general testing but a VNA isnt really suitable for that, it expects a characteristic R-50 termination.

Most of my testing is with a B&K 5.5 digit DMM to measure a capacitor, and resonant circuit with an AWG and MW diode probe (10 USD), to calculate inductor values. But thats $1000 USD in gear.

The B&K handheld LCR Meters are now up to 500 USD, but not great for RF use.

????

On Wednesday, July 15, 2026, David VK2CZ via groups.io <16240244c1=gmail.com@groups.io> wrote:

Hello Dave,

Your development sounds very interesting. Having spent 10 years of my career in manufacturing a significant amount of RF systems with NEC and Ericsson, component validation was only sampled using frequencies up to 5kHz.. we relied heavy on manufacturer QA.

If was to assess say a resistor at say 50Mhz, I'd probably use a component jig with a network analyzer.. then of course using kelvin clips become useless..

That said, still thinking of possible applications.

David VK2CZ

Wednesday, 15 July 2026

Re: [Amateur-repairs] Test Equipment Question

Very good insider info. Such is used in quartz crystal manufacturing for production testing but such co's wouldnt want my approximation of test eq, they have money for real equipment.

A TW XTAL house sent me a prototype crystal run with QA data to 6 d.p., so thats beat my meager attempt by quite a bit. That was SSB filter XTALS for the Drake TR rigs.

Such gear is so far beyond most Amateur uses I cant imagine who'd want it. Ive used it to exactly verify network calculations and components, but how often is that done?

An inexpensive Nano could be used for general testing but a VNA isnt really suitable for that, it expects a characteristic R-50 termination.

????

On Wednesday, July 15, 2026, David VK2CZ via groups.io <16240244c1=gmail.com@groups.io> wrote:

Hello Dave,

Your development sounds very interesting. Having spent 10 years of my career in manufacturing a significant amount of RF systems with NEC and Ericsson, component validation was only sampled using frequencies up to 5kHz.. we relied heavy on manufacturer QA.

If was to assess say a resistor at say 50Mhz, I'd probably use a component jig with a network analyzer.. then of course using kelvin clips become useless..

That said, still thinking of possible applications.

David VK2CZ

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Re: [Amateur-repairs] Test Equipment Question

Hello Dave,

Your development sounds very interesting. Having spent 10 years of my career in manufacturing a significant amount of RF systems with NEC and Ericsson, component validation was only sampled using frequencies up to 5kHz.. we relied heavy on manufacturer QA.

If was to assess say a resistor at say 50Mhz, I'd probably use a component jig with a network analyzer.. then of course using kelvin clips become useless..

That said, still thinking of possible applications.

David VK2CZ

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[Amateur-repairs] Test Equipment Question

Since the Users here are more 'hands on...'

I have developed a very low cost L-C-R test system that can measure

down to 5 decimal place resolution and about 0.1 % accuracy.

AT RF FREQUENCY

Commercial units are on the order of $5,000 - 20,000 USD for a few MHz test frequency.

My system should be able to go VHF, but I haven't verified that.

Is this of any use to the Amateur world?

Cost "guess," $200 - 2000 USD, depending on how much ancillary equipment you might already have.

Dave K8BYP

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Friday, 27 March 2026

[Amateur-repairs] Farnell Transmitter Test TTS520

Any manuals, Schematics, Guide or basic info on this piece of old Test Gear please.
Any Help Really appreciated regards Chris.

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Saturday, 3 January 2026

Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

Acom amps also use this valve and its bigger brother 1500. The circuits are downloadable.

There is a lot if protection built in.

If you find a willing volunteer, with said amp, you could try it in that.

I have one here, and would happily swap it over if you lived closer.

I have not seen valve testers, that take this series of valves.

If you have an Acom dealer near you, get in touch.

Andrew

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On January 3, 2026, at 16:46, Jim Shorney via groups.io <jimNU0C=gmail.com@groups.io> wrote:

Interesting. Full disclosure, I have no experience with this amp but I did peruse the schematics. I do have some experience with tetrodes (NCL-2000). There is a lot going in there. Are the proper voltages actually making it to the tube sockets in TX? Does the step-start function normally with no tubes installed? It is possible you have a high voltage fault in one of the tubes. It might be worthwhile to test each tube by itself in the amp with airflow from the open socket blocked off.

There is an active Alpha group on Facebook that may be able to provide some guidance.

On Sat, 03 Jan 2026 08:19:30 -0800
"David Mitchell via groups.io" <wb2pjh=gmail.com@groups.io> wrote:

Hi Jim,
I've got a fair amount of technical experience and checked all the voltages at all the test points and all were FB. The Penta 4CX1000A subs that Alpha used were notorious for screen grids shorting out, but finding nothing when testing each tube with my VOM, need to find someone reputable who can test these tubes in a proper test fixture to see if they're failing under load.

I neglected to add that the two 20 amp main fuses did NOT blow, only the 2A fuse that runs the control circuitry and CPU.

Thanks,

Dave WB2PJH

--

73

-Jim
NU0C

Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

Interesting. Full disclosure, I have no experience with this amp but I did peruse the schematics. I do have some experience with tetrodes (NCL-2000). There is a lot going in there. Are the proper voltages actually making it to the tube sockets in TX? Does the step-start function normally with no tubes installed? It is possible you have a high voltage fault in one of the tubes. It might be worthwhile to test each tube by itself in the amp with airflow from the open socket blocked off.

There is an active Alpha group on Facebook that may be able to provide some guidance.

On Sat, 03 Jan 2026 08:19:30 -0800
"David Mitchell via groups.io" <wb2pjh=gmail.com@groups.io> wrote:

> Hi Jim,
> I've got a fair amount of technical experience and checked all the voltages at all the test points and all were FB. The Penta 4CX1000A subs that Alpha used were notorious for screen grids shorting out, but finding nothing when testing each tube with my VOM, need to find someone reputable who can test these tubes in a proper test fixture to see if they're failing under load.
>
> I neglected to add that the two 20 amp main fuses did NOT blow, only the 2A fuse that runs the control circuitry and CPU.
>
> Thanks,
>
> Dave WB2PJH

--

73

-Jim
NU0C

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Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

Hi Jim,

I've got a fair amount of technical experience and checked all the voltages at all the test points and all were FB. The Penta 4CX1000A subs that Alpha used were notorious for screen grids shorting out, but finding nothing when testing each tube with my VOM, need to find someone reputable who can test these tubes in a proper test fixture to see if they're failing under load.

I neglected to add that the two 20 amp main fuses did NOT blow, only the 2A fuse that runs the control circuitry and CPU.

Thanks,

Dave WB2PJH

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Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

Can you apply power with the valves removed, see if you still have high current?

Abdrew

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On January 3, 2026, at 03:18, David Mitchell via groups.io <wb2pjh=gmail.com@groups.io> wrote:

I tried to contact Penta and got no response, but if you think that they test their own tubes, I'll give it another shot. The amp had been working fine but quit in the middle of a QSO. When I opened it up, the wirewound resistor in the startup circuit was fried and one of the three plate blocking caps was shorted. I replaced everything but as soon as I applied the HV, the plate current skyrocketed and the resistor started heating up fast. I've checked the sockets, the resistors in the RF deck, and everything checks out.

Replacement tubes cost more than the amp is worth, which is why IMHO the next step is to get the tubes tested by someone who knows what they're doing.

Sorry for the typo - the tube is obviously a 4CX1000A.

73,

Dave

Friday, 2 January 2026

Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

It sounds like maybe you lost grid bias. With a tetrode amp you should always check that all operating voltages are present and correct before you put the tubes in.

On Fri, 02 Jan 2026 19:18:36 -0800
"David Mitchell via groups.io" <wb2pjh=gmail.com@groups.io> wrote:

> I tried to contact Penta and got no response, but if you think that they test their own tubes, I'll give it another shot. The amp had been working fine but quit in the middle of a QSO. When I opened it up, the wirewound resistor in the startup circuit was fried and one of the three plate blocking caps was shorted. I replaced everything but as soon as I applied the HV, the plate current skyrocketed and the resistor started heating up fast. I've checked the sockets, the resistors in the RF deck, and everything checks out.
>
> Replacement tubes cost more than the amp is worth, which is why IMHO the next step is to get the tubes tested by someone who knows what they're doing.
>
> Sorry for the typo - the tube is obviously a 4CX1000A.
>
> 73,
> Dave

--

73

-Jim
NU0C

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Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

I tried to contact Penta and got no response, but if you think that they test their own tubes, I'll give it another shot. The amp had been working fine but quit in the middle of a QSO. When I opened it up, the wirewound resistor in the startup circuit was fried and one of the three plate blocking caps was shorted. I replaced everything but as soon as I applied the HV, the plate current skyrocketed and the resistor started heating up fast. I've checked the sockets, the resistors in the RF deck, and everything checks out.

Replacement tubes cost more than the amp is worth, which is why IMHO the next step is to get the tubes tested by someone who knows what they're doing.

Sorry for the typo - the tube is obviously a 4CX1000A.

73,

Dave

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Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

That is a typo. A 4CX10000 won't fit inside an Alpha 8410

On 1/2/2026 10:49 AM, Andrew Lenton wrote:
> Just noticed the extra zero, Ok 10KW output, will need 1Kw drive in
> common grid mode, or 500 Watts if grid driven!
>
--
73 de Mike, W1NR

THAT was the equation. EXISTENCE!... SURVIVAL... must cancel out...
programming!

- Ruk -

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Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

Just noticed the extra zero, Ok 10KW output, will need 1Kw drive in common grid mode, or 500 Watts if grid driven!

Not to mention you will need a 20kW transformer assuming 50% efficiency!

That is 28A at 240V per phase, double. The current at 110Vs!

Interesting project, your ham licence allows you 1.5KW, well you will have headroom for digital modes!

What am I missing, is this for SW broadcast? Maybe FM?

SSB you could get 12KW PEP, still less than Italian stations 😎😎!!!

Andrew

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On January 2, 2026, at 14:25, David Mitchell via groups.io <wb2pjh=gmail.com@groups.io> wrote:

I'm trying to finish the repairs on my Alpha 8410 and would like to know if there is a company that has the proper fixture to test the two Penta 4CX10000a tubes? I checked for obvious shorts between the grids, cathode and plates and they all look OK. There aren't many repair facilities around that service amps that use these tubes.

73,

Dave WB2PJH

Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

You amp is probably the best test bed for your valves?

Andrew

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On January 2, 2026, at 14:25, David Mitchell via groups.io <wb2pjh=gmail.com@groups.io> wrote:

I'm trying to finish the repairs on my Alpha 8410 and would like to know if there is a company that has the proper fixture to test the two Penta 4CX10000a tubes? I checked for obvious shorts between the grids, cathode and plates and they all look OK. There aren't many repair facilities around that service amps that use these tubes.

73,

Dave WB2PJH

Re: [Amateur-repairs] Company Needed to test 4CX1000a Tubes

Penta claims to test them, did you already reach out to them?

Check with Econco or Kennatron?
What are the symptoms?

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[Amateur-repairs] Company Needed to test 4CX1000a Tubes

I'm trying to finish the repairs on my Alpha 8410 and would like to know if there is a company that has the proper fixture to test the two Penta 4CX10000a tubes? I checked for obvious shorts between the grids, cathode and plates and they all look OK. There aren't many repair facilities around that service amps that use these tubes.

73,

Dave WB2PJH

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