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 Post subject: CONNECTING CABLE`S FOR HEATH SB 301 AND 401
PostPosted: Jun Mon 14, 2021 2:54 pm 
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Joined: Sep Sat 28, 2019 2:05 pm
Posts: 259
HI everyone i am wondering if there is an equivalent type of coax i can use instead of the rg-62u for pairing the 301 and 401 together ? thanks again


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 Post subject: Re: CONNECTING CABLE`S FOR HEATH SB 301 AND 401
PostPosted: Jun Mon 14, 2021 10:19 pm 
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Location: Sayreville, NJ 08872
HAMmer wrote:
HI everyone i am wondering if there is an equivalent type of coax i can use instead of the rg-62u for pairing the 301 and 401 together ? thanks again

The Heathkit design pairing of the 301 and 401 and similar "SB's" was designed around using 93 ohm type coaxial cable for interconnections. I wouldn't screw with the design intent.

Want something other then RG-62U, start here:
https://www.google.com/search?client=fi ... 3+ohm+coax

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https://www.manualman.com


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 Post subject: Re: CONNECTING CABLE`S FOR HEATH SB 301 AND 401
PostPosted: Jun Tue 15, 2021 9:59 pm 
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There is a thread on QRZ where this is briefly discussed:

https://forums.qrz.com/index.php?threads/restoring-heathkit-sb301-and-401-really-need-some-advise.332642/page-2

In that thread someone who made and sold cables at the time had switched to RG59/U due to supply and quality issues. One man's opinion so take it for what it's worth.

RG62 is 93 Ohm, 12.8 pF/ft, 85% VP
RG59 is 75 Ohm, 20.4 pF/ft, 66% VP
RG58 is 52 Ohm, 28.5 pF/ft, 66% VP

They are all about the same loss/100 ft

I suspect the capacitance per foot is the critical parameter. If so then 59 may be acceptable but you might want to look at those other 93 Ohm cables first. If the propagation velocity is important then 59 will be no better than 58.

Actually it looks like those other 93 Ohm cables are all just RG62 so get some if you can or take a chance on lower impedance cables.


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 Post subject: Re: CONNECTING CABLE`S FOR HEATH SB 301 AND 401
PostPosted: Jun Tue 15, 2021 10:48 pm 
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The capacitance per foot is the only somewhat critical parameter.

I have used RG-59 for connecting SB-30x/40x pairs without issue. Keep the cables as short as feasible and it won't be a problem.

Rodger WQ9E


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 Post subject: Re: CONNECTING CABLE`S FOR HEATH SB 301 AND 401
PostPosted: Jun Wed 16, 2021 11:30 am 
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Joined: Sep Sat 28, 2019 2:05 pm
Posts: 259
Thanks everyone i will do some shopping around


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 Post subject: Re: CONNECTING CABLE`S FOR HEATH SB 301 AND 401
PostPosted: Jun Thu 17, 2021 2:28 am 
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Location: Lincoln City, OR 97367
Greetings, All:

I find this interesting. I have no experience with interconnecting Heathkit gear, but I use plain old audio cables of whatever length is convenient to interconnect my Collins S-line.... and the gear works just fine. I do use 50 ohm coax for the transmitter output since there's a hundred watts there, but all the low level stuff is whatever I have handy.

There are three possibilities:

1. I've been lucky.
2. Collins gear is more forgiving than Heathkit Gear.
3. It really doesn't matter what you use with Heathkits either.

I wonder which of the above it is?

Regards,

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 Post subject: Re: CONNECTING CABLE`S FOR HEATH SB 301 AND 401
PostPosted: Jun Thu 17, 2021 2:17 pm 
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Joined: Apr Wed 01, 2020 7:22 pm
Posts: 328
I've used Heathkits, Drakes and Collins gear which require those coaxial interconnecting cables.

What I have found is that if you use a cable different from the recommended cable, and particularly if you use a cable with higher rated capacitance per foot, drive signals such as LMO, HFO, Xtal Osc. etc. will suffer to various extents and have an effect on receive sensitivity, tuning and power output.

You can overcome some of these issues by performing an alignment with the cables you intend to use, but the rig won't be at optimal alignment if you chose to operate the rigs independently.

Using the recommended cable ensures the alignment remains correct, or as close to correct as possible, when the rigs are paired or operated separately...

Some of the cables can be shielded audio cable if they are carrying DC, audio or ground connections, but not the cables carrying RF signals.

That's what I have found...! 73...Jordan VE6ZT


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