[Amps] about the WARC bands of the Heathkit SB-220.

[David G4FTC]

Hi Kouichi,

I have two SB220s and they both work well on the WARC bands.

The input circuit of the SB220 is a low Q PI network which is effectively a low pass filter, so, if you want to operate on 12m, then you need to set the band switch to 10m. Similarly for operation on 17m you need to set the  band switch to 15m, and for 30m set the band switch to 20m.

The SWR input match to the amp will not be perfect (can be up to 2:1) but shouldn't give your transceiver any problems.

The output PI network will not be optimum but it does tune and load and you should be able to get about 900 watts output on the 30 and 17m bands and about 600 to 700 watts out on 12m.

Initially I was concerned that the anode choke may have a resonance within one of the WARC bands, but I haven't experienced any problems.

Hope this helps

David G4FTC


________________________________
From: Amps <amps-bounces at contesting.com> on behalf of Kouichi Ueno <kueno at wine.ocn.ne.jp>
Sent: 07 October 2024 12:28
To: amps at contesting.com <amps at contesting.com>
Subject: [Amps] about the WARC bands of the Heathkit SB-220.

Nice to meet you.
My name is Kouichi Ueno, JI1FGX/DU9.

I have a question about the Heathkit SB-220.
I would like to know if the Heathkit SB-220 can ONAIR 10MHz, 18MHz, and 24MHz?
I know that the band switch does not have these bands.
Do I need to modify the SB-220?

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