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SG-LAB 25 watt 23cm Amplifier


#1

Has anyone purchased SG-Lab’s new 23 cm RF amplifier? Any reports?

http://www.sg-lab.com/AMP1300/amp1300.html

73, Andrew VK1AD


#2

I’m tempted by more power for my 13cms gear. But first I want to try bigger antennas and dual cables. You can get 0.4dB improvement by not using the built c/o relay on the 13cms unit. I’m just imagineering how to do 2x low windage antennas that are repeatable with two lengths of feeder. Two lengths of RG400 weighs less than a PA and battery. Adding an inline preamp is also on the list to try.

But more power is always like light to a moth, it draws you in with its seductive charms :slight_smile:


#3

One of these PC board Yagi antennas is 10 dB. You could stack them. Only $7 each, but shipping might be expensive. He also does custom antennas.

https://www.wa5vjb.com/products2.html

I have one of his 23 cm Yagis for my 1.2 GHz HT.

wunder


#4

Several of WA5VJB antennas are available from Sam G4DDK (http://www.g4ddk.com/Prices.html)


#5

I think your 10dB is optimistic or is the front<>back ratio. 6-7dBi is the claimed gain and a 13cms version was measured at 5.6dBi. I have about 12-13dBi for the double double quad already. Another of those stacked would be 15-16dBi and is manageable on a summit and only costs a dollars/pounds plus my time. The hardest part is making a low loss phasing harness. That probably could be made on PCB, but on Rogers Duroid rather than FR4.

An amp is shiny though!


#6

Seems like the answer is no, Andrew!


#7

I am consiidering a purchase. I would like to be able to switch it in just when necessary, and I’m not sure that it could be left in circuit when powered off. I may need to arrange a couple of low loss (and low hold current) relays to switch it in and out.

I have a 4Ah LifePo battery, which typically has between 1 and 2 Ah left after a UKAC 2.5 hour activation. I don’t think that would support the amplifier in use throughout, and indeed there would be no need to use it throughout.

And, as Andy observers, they are very shiny :smile:


#8

Andrew,

No I haven’t tried or got one but would be a neat way to get some power out of a 23cm 1W Alinco HH. Is there a price? I couldn’t see one on the SG site. I wonder what the output is with a bit under 1W as the input? I think the spec says the drive is 1.6W.

How would it go with one of Mark’s preamps? Then you need a sequencer probably and a bigger box…
Compton


#9

Looks to me like the preamp in the amp box is pretty good, a NF below 1 db and enough gain to cancel out the feedline loss. And as it is intended for linear use, the output should be linearly related to input, 10 db gain would produce 10w out for 1w in. Most of these amplifier tend to compress a little so you may get even more out for 1w in. All conjecture though and an email to the info address usually gets a prompt reply.

73 Andrew VK1DA/VK2UH (one of the other Andrews)


#10

Ah, I was reading too fast. The spec is “Average Gain 10 dBi”, so the claim is 7 dB over dipole as you point out. I don’t have any 13 cm gear, so I was quoting the data sheet.

wunder


#11

Yes, I ,missed that.
Compton


#12

The price of 25W Pa for 1296 MHz is 162 Euro +8 Euro for economy shipping


#13

Hristiyan wrote they’re out of stock at the time and it’ll take about a month for the new charge to arrive. Now waiting patiently for the 23 cm PA. :yum:

Ahoi
Pom


#14

VK1 has just taken receipt of three SG-Lab 23cm 25 watt afterburners and a new 23cm transverter for a newcomer to 1296 MHz. Woohoo more power on 23 leads to greater distance records and more S2S opportunities :slight_smile:

We now have 7 activators on 23cm: VK1AD, VK1DA, VK1RX, VK1MA, VK1AT, VK1MCW and VK1MIC. I will add Compton VK2HRX to the group when he visits VK1.

In addition to the activator group, we have an enthusiastic and dedicated 23cm chaser group comprised of: VK1KW, VK1JA, VK1BG, VK1DO and VK2TWR.

Andrew VK1AD


#15

Gosh, they are lovely and shiny. When do they go out and get dirty and scratched?


#16

Hi Andrew,

congratulation to your brand new 23 cm amplifiers.

I have had my for some time and am very happy with it. The HF Vox works fine and the extra preamp is very helpful along with the somewhat dumb FT-817. The specified output power together with the transverter is achieved and the modulation is clean.

73 Chris


#17

The amp and my new 14 el. 23cm yagi give me a extra boost of 20db and 100 times more EIP, what a huge difference.

73 Chris


#18

Ginini to Gibraltar is line of sight I think & about 200KM.


Pick a date I say!!
Compton
(who can bring 60W to the party)


#19

Fired up this morning working the VK1 VHF-UHF DX Net from the deck, not quite SOTA but the outside temperature was 3 degrees C, so almost SOTA like. Same set up as I would have on a summit but without the luxury of a table and a bench seat.

Andrew VK1AD


#20

Ginini as a premier 23cm launchpad is ruined by the recent installation of a 23cm beacon.

Mt Gingera, Mt Coree or Mt Tumorrama would be next on the list. I’m planning to go to Mt Tumorrama VK2/SW-027 next Saturday morning.

Andrew VK1AD