Heathkit Trimpots - UK Vintage Radio Repair and Restoration Discussion Forum

m0cemdave · 18th Aug 2023, 10:52 pm

Anyone who restores Heathkit equipment will need to replace the occasional trimpot.

These are usually the large skeleton type with distincive blue thumbwheels, made by CTS in the USA, and the pin spacing is different from those in the Rest Of The World.

Some years ago I needed a few for a restoration and after much searching I discovered that they were still made, and available from Mouser. *

Recently I needed some more trimmers to repair another piece of Heathkit equipment, and found that they are now listed (like a lot of other through-hole components) as "no longer manufactured".

Fortunately, after more searching, I found that a modern equivalent is manufactured by Amphenol-Piher in their PT15 range and this is also available via Mouser. Nearly all Piher trimpots have the current standard pin spacing, so care is needed to pick the correct version when ordering.

Piher part numbers refer to Horizontal and Vertical ADJUSTMENT, which is the opposite to Horizontal and Vertical MOUNTING. Beware of this when ordering, especially as the pictures on the Mouser website generally show a vertical mounting type.

Thumbwheel adjustment requires rotor style N. Thumbwheels (white, not blue) are ordered seperately and are a press fit into the pot boss.

The range of values is 1.0, 2.0, 2.2, 2.5, 5.0 x decades, and standard tolerance is 20%.

The correct size replacements are:
PT15NH06 for the Horizontal adjust = Vertical mounting type
and
PT15NV18 for the Vertical adjust = Horizontal mounting type, with two tags at the sides for the rotor connection.

for example:
20k Lin Vertical mounting = PT15NH06-203A2020
500 ohms Lin Horizontal mounting = PT15NV18-501A2020

plus thumbwheel 5371-CR

--

* Although an American distributor, Mouser has a UK website and ordering is simple. They deal with any import duties and collect the VAT, so there are no extra fees to be paid on delivery.

McMurdo · 19th Aug 2023, 1:18 pm

I get mine from Rapid in the uk, they do the red and black thumbwheels and also the 6mm knurled shaft adapters. I dont fit them to heathkit equipment but they're found in old industrial systems for various things. The horizontal mount ones come in 2 different wiper-pin locations although when Ive oprdered the wrong one, I've been able to adapt it.

These Piher pots were a subsidiary of uk aerospace company Meggitt PLC who at the end of last year were bought out by US company Parker and delisted from the LSE.

https://static.rapidonline.com/pdf/51-9077.pdf

18th Aug 2023, 10:52 pm	#1
m0cemdave Octode Join Date: Feb 2009 Location: Bletchley, Buckinghamshire, UK. Posts: 1,152	Heathkit Trimpots Anyone who restores Heathkit equipment will need to replace the occasional trimpot. These are usually the large skeleton type with distincive blue thumbwheels, made by CTS in the USA, and the pin spacing is different from those in the Rest Of The World. Some years ago I needed a few for a restoration and after much searching I discovered that they were still made, and available from Mouser. * Recently I needed some more trimmers to repair another piece of Heathkit equipment, and found that they are now listed (like a lot of other through-hole components) as "no longer manufactured". Fortunately, after more searching, I found that a modern equivalent is manufactured by Amphenol-Piher in their PT15 range and this is also available via Mouser. Nearly all Piher trimpots have the current standard pin spacing, so care is needed to pick the correct version when ordering. Piher part numbers refer to Horizontal and Vertical ADJUSTMENT, which is the opposite to Horizontal and Vertical MOUNTING. Beware of this when ordering, especially as the pictures on the Mouser website generally show a vertical mounting type. Thumbwheel adjustment requires rotor style N. Thumbwheels (white, not blue) are ordered seperately and are a press fit into the pot boss. The range of values is 1.0, 2.0, 2.2, 2.5, 5.0 x decades, and standard tolerance is 20%. The correct size replacements are: PT15NH06 for the Horizontal adjust = Vertical mounting type and PT15NV18 for the Vertical adjust = Horizontal mounting type, with two tags at the sides for the rotor connection. for example: 20k Lin Vertical mounting = PT15NH06-203A2020 500 ohms Lin Horizontal mounting = PT15NV18-501A2020 plus thumbwheel 5371-CR -- * Although an American distributor, Mouser has a UK website and ordering is simple. They deal with any import duties and collect the VAT, so there are no extra fees to be paid on delivery.

19th Aug 2023, 1:18 pm	#2
McMurdo Dekatron Join Date: Jun 2009 Location: Staffordshire Moorlands, UK. Posts: 5,165	Re: Heathkit Trimpots I get mine from Rapid in the uk, they do the red and black thumbwheels and also the 6mm knurled shaft adapters. I dont fit them to heathkit equipment but they're found in old industrial systems for various things. The horizontal mount ones come in 2 different wiper-pin locations although when Ive oprdered the wrong one, I've been able to adapt it. These Piher pots were a subsidiary of uk aerospace company Meggitt PLC who at the end of last year were bought out by US company Parker and delisted from the LSE. https://static.rapidonline.com/pdf/51-9077.pdf __________________ Kevin