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Help with RX/TX relay

Tech5

Active Member
Jun 24, 2023
32
27
28
Sweden near the Arctic Circle
Hi guys!

Working on a Royce 642 and thanks to @Shummy that shared the service manual my life became much easier. First thing was to fix a bad power switch which was an easy task since the switch is a DPDT and only one pole was used, which was burnt, but the other one was as new.

The TX/RX relay is in bad condition and it has to be replaced, but this relay (Matsushita AW6221) is discontinued. There is a relay though (AW622144) that has same footprint and can be ordered from a small number of distributors, but have any of you replaced this relay with another type that will fit into same layout?

Power switch.jpgRelay HB2-DC12V AW6221.jpg
 

I have a Pace 8193 that I replaced the relay with an Aromat AW622108. Dropped right in.

I think anything labeled "HB2-DC12V" should work, but I haven't tried every possible variation.
 
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The pinout is a bit out of the ordinary, with the six contact pins spaced 1/10 inch apart. Trouble with a soldered-in circuit-board relay is the pins have to match the holes in the pc board.

RF Parts doesn't list it any more, but fleabay turns up multiple options. Hard part is finding someone who will sell you just one. First search returns were for lots of five. This guy lists a single unit sale.

https://www.ebay.com/itm/1155617353...pid=5336136228&customid=&toolid=10001&mkevt=1

73
 
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I have a Pace 8193 that I replaced the relay with an Aromat AW622108. Dropped right in.

I think anything labeled "HB2-DC12V" should work, but I haven't tried every possible variation.
Thank you TM86 for pointing that out!
It seems that there are quite a big number of relays with HB2 board pattern. I will certainly have a look at these relays because the one in this radio only switches the power rails for RX and TX and the coil is controlled by the PTT so nothing fancy really.
 
Last edited:
The pinout is a bit out of the ordinary, with the six contact pins spaced 1/10 inch apart. Trouble with a soldered-in circuit-board relay is the pins have to match the holes in the pc board.

RF Parts doesn't list it any more, but fleabay turns up multiple options. Hard part is finding someone who will sell you just one. First search returns were for lots of five. This guy lists a single unit sale.

https://www.ebay.com/itm/1155617353...pid=5336136228&customid=&toolid=10001&mkevt=1

73
Thank you for the link nomadradio!

It seems that it is used relays so think I rather buy a brandnew. I agree that the pinout is a bit odd and have to admit that I have never had such a relay in my hand as far as my memory serves me and been into electronics for nearly 35 years lol. I will have a close look at the data sheets for the HB2 and get back with information in case someone else gets into same trouble.
 
After lots of searches for a relay with same land pattern and pinout I realised that I will have to bite the bullet and buy it from Ebay. The part number is Aromat HB2-DC12V AW622198. I placed the order today and now I will have to wait for the shipping from China. :giggle:

Attached is part from the data sheet for this relay. I will be back as soon as I have the relay and tested it.
HB2-DC12V.jpg
 
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So the Aromat TX/RX relay finally arrived and already soldered into the Royce 642. I know people like pictures so I pass some from my shack as well as both the relays - Matsushita & Aromat.
 

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That's a nice looking radio. Glad you're fixing it up and not cutting the cord. The only Royce I have experience with is a 1-625, it had the vertical riser cards and was a pain to even align. But, it was a nice looking radio, and it found a new home with a collector.
 
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That's a nice looking radio. Glad you're fixing it up and not cutting the cord. The only Royce I have experience with is a 1-625, it had the vertical riser cards and was a pain to even align. But, it was a nice looking radio, and it found a new home with a collector.
This Royce belongs to a good friend of mine who is a collector and he sends me radios to fix quite often and I find it to be both a relaxing and a real fun job. Yes, this Royce is a real beauty and it sure is worth to bring it back to a descent life. I must say that this radio is very thankful when it comes to reach all test points and for all the alignments. Next radio is a Spitfire MK II (Robyn T123B) and now I will have to use my tube tester made 1962, but it still work like a charm and I find it real fun with tubes. :)

Well ... must say that this RX/TX relay was a special one and a relay I have never ever seen before.
 
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Im still hopeful to add a nice tube radio to my collection, mostly for a backup in the event of an EMP, as the tubes aren't as sensitive to the effects of an emp. I found one once, but it was rusted through like it was used as a trotline weight. I noticed you're the second post this week to include a picture of your bench with fuel pumps on it. I hope it isn't a sign of things to come.
 
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I have both ham and CB tube radios in my shack and now you got me thinking about EMP and that is good thinking these days! I am working a lot on electronic and electrical stuff in E-tec snowmobiles and these fuel pumps are from E-tec's. A friend of mine owns them and I promised to test them all before the winter. I am living approximately 70 km south of the Arctic Circle so snowmobiles are quite common here. :)
 

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