[Heath] Fwd: Fwd: Final transistors for SB 104A
Dave Edwards
kd2e at comcast.net
Thu Sep 23 08:14:24 EDT 2021
That 6030 is used on some vintage Yaesu rigs also.
I bought a bunch of them years ago when I had a SB104. They were cheap
then!
....Dave
On 9/22/21 11:49 PM, Steven Feinsmith wrote:
> Thank you, Chris, for clearing this up for me about the MFC6030A
> voltage regulator by Motorola. Also, you are correct that the HP-1144
> power supply had no crowbar to protect the transceiver included
> SB-634, SB-644A, and SB-614 through power chain links. The HP-1144A
> had an improved design including a crowbar circuit.
>
> The price for MFC6030A went up crazy price at:
>
> https://store.americanmicrosemiconductor.com/mfc6030a.html
> <https://store.americanmicrosemiconductor.com/mfc6030a.html>
>
> Fortunately, my HP-1144 is working except for my concern with a pair
> of filter capacitors because the top terminals were not flat. I do not
> know if it is normal because I did not have another HP-1144 or
> HP-1144A for comparison. I plan to pull out both filter capacitors to
> test for leakage and find their capacitance range to ensure that they
> are ok or not. Secondly, I plan a test ripple from them and use my
> infrared image gun to see thermal reading for abnormal.
>
> Nowadays, it has become more difficult to buy large capacitors because
> many companies are no longer in stock because of the pandemic
> incidents. All vendors jacked up the price into unreasonable costs for
> the replacement. That is why I got a switching power supply designed
> for the Ham radio system to replace the H-1144 in the SB-604 chassis.
> The advantage of the switching power supply is that it is much lighter
> in weight and smaller physically with a cooling fan. The device has
> built-in overvoltage and overcurrent protection with adjustable
> voltage and noise. The device is a TekPower TP30SWV 30 Amp DC 13.8V
> Digital Switching Power Supply with Noise Offset.
>
> I know many Heathkit items need new parts replaced but are no longer
> available. So many Heathkit items posted on eBay could be around 90%
> not working while sellers want for hundred of dollars and said, they
> applied the power and it on. That is all. That was not correct how
> they tested the equipment before selling it to buyers. Can we buy a
> non-working car at a price that is supposed to be a working car? Of
> course, no! That problem with sellers and eBay. Fortunately, I have
> experience in electronics and can repair anything even if I have to
> change the design to replace non-available components.
>
> It was not Heathkit's fault because they did not know what the future
> would be. The problem is electronic component manufacturers like
> Motorola, Texas Instruments, Emiac, and many others enjoy
> discontinuing the products and allow many people to cry and face jack
> up the prices as much as gold prices.
>
> Thank you very much,
> Steven
>
>
>
> On Wed, Sep 22, 2021 at 10:32 PM Chris Iwata <chrisiwata at aol.com
> <mailto:chrisiwata at aol.com>> wrote:
>
>
> When I mentioned restoring the SB104 that meant bringing it back
> to as originally sold. No workarounds.
>
> The MFC6030 voltage regulator IC in the SB104 is the same as in
> the HP1144 power supply. On my SB104 it failed, and the one in the
> power supply also failed. This is a 4 terminal regulator no longer
> in production and only Motorola made it. I couldn't even find an
> NTE replacement. ICs theoretically last almost forever, but
> practically they don't. Ultimately I used a 7805K for the SB104
> and completely redid the power supply using a LM723 regulator.
>
> The computer grade cap in the power supply used to be cheap as
> surplus when computers used TTL ICs. but no more. The one in my
> power supply failed also. The 1144 power supply I own had no
> crowbar overvoltage protection, I added it myself. This was added
> in 1144A version. This is very important if you want to protect
> your SB104 from disastrous failure.
>
> One final RF transistor blew. This happened from high VSWR.
> Rather than buying a matched pair or quad, I redid the final to
> use only 2 transistors at reduced wattage.
>
> Chris, KL7DM
>
> On 9/22/2021 4:51 PM, Steven Feinsmith wrote:
>> First of all, both SB-104, SB-104A, and SB-230 are not dying. The
>> 2N6456 RF transistors have indeed become more difficult to find
>> nowadays. The greedy eBay sellers pumped for around 100 dollars
>> each. Of course, no one is buying 400 dollars. There is a big
>> issue about whether a matched quads may be impossible. I did
>> mention in my previous message that I should buy an old rig that
>> uses the 2N6456.
>>
>> The same problem with SB-230 uses a 1KW tube that was no longer
>> stock and depleted from the vendor's inventory.
>> Some Ham users use Russian-made microwave tubes to take over with
>> some modifications.
>> The front panels use a Panaplex display. It is a gas discharge
>> display that was very popular and easy to read. There was a
>> slight problem with the Panaplex because it requires 180 volts to
>> run the gas discharge. It tended to give out some electrical
>> noise. There are articles about converting Panaplex to LED for
>> both SB-634, station, and SB-104A, transceiver.
>>
>> Now, I am working on a new PCB for the SB-104A display to run
>> with the LED instead of Panaplex.
>>
>> The problem is with the new ham radio transceivers that
>> physically shrink a lot, but it had many features, such as
>> digital modes with USB ports. The amplifier tends to use
>> high-power transmitting tubes now as MOSFET. The price tag, OUCH!
>> I am poor as a retiree and earn a social security retirement
>> check every month.
>>
>>
>> You mentioned voltage regulators. My SB-104A is running fine as a
>> licensed operation tested them. I checked everything with my
>> DMM/VTVM to ensure voltages are within specification. Can you
>> explain the details about the voltage regulators. I also found my
>> HP-1144 power supply seems to have two filter capacitors that may
>> need replacement. The cost is crazy as I bought a switching power
>> supply that provides matched voltage and provides 30A instead of
>> 20A with overvoltage and overcurrent protection. The advantage
>> with the switching power supply was that it was very light
>> compared with a massive transformer's weight.
>>
>> Just try to keep Heathkit alive ahead of time!
>> Steven
>>
>>
>> -------- Forwarded Message --------
>> Subject: Re: [Heath] Fwd: Final transistors for SB 104A
>> Date: Wed, 22 Sep 2021 12:56:01 -0700
>> From: Chris Iwata <chrisiwata at aol.com>
>> <mailto:chrisiwata at aol.com>
>> To: ka9dzr at aol.com <mailto:ka9dzr at aol.com>
>>
>>
>>
>>
>> If you luck out and find some, bear in mind that you have to
>> buy matched pairs.
>>
>> Theoretically, you have to buy matched quads. But you can
>> probably be OK with matched pairs
>>
>> Expect to pay a premium, those stud mount RF transistors
>> haven't been made for at least 20 years. A guess would be at
>> least $50 each
>>
>> Your best bet is to buy a junked SB104
>>
>> The SB104 will become unrestorable due to unavailability of
>> the Final transistors, the Nixie tubes, the Nixie driver IC,
>> and the voltage regulator IC.
>>
>> Chris, KL7DM
>>
>>
>>
>> On 9/22/2021 10:18 AM, ka9dzr--- via Heath wrote:
>>> has anyone fine any replacement finals for the sb-104a yet
>>> tnx ka9dzr Dennis
>>>
>>> ------------------------------------------------------------------------
>>> From: heath at puck.nether.net <mailto:heath at puck.nether.net>
>>> To: heath at puck.nether.net <mailto:heath at puck.nether.net>
>>> Sent: 11/24/2014 4:56:23 PM Central Standard Time
>>> Subject: [Heath] Final transistors for SB 104A
>>>
>>> I have learned that the 2n6456 final RF transistors are
>>> no longer available and I NEED to replace the four (4)
>>> in a Heath SB 104A. Has anyone found a suitable
>>> replacement transistor for this application? I have
>>> thoroughly checked with RF Parts and they no longer
>>> stock those transistors.
>>> Does anyone have experience substituting the final
>>> transistors in the SB 104A? If so what did you use as a
>>> replacement and do you know where they can be found?
>>> Thanks and 73, John, K5PGW
>>> _______________________________________________
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